{"title":"William Optics Visual Accessories","description":"\u003cp\u003eWilliam Optics visual accessories make observing with a refractor more comfortable and versatile. Dura Bright 99% dielectric diagonals come in 1.25\", 2\" and a 2\" SCT-threaded version for bright, comfortable viewing angles.\u003c\/p\u003e\u003cp\u003eErecting prisms, including 90° and 45° 1.25\" models and versions for the RedCat WIFD and Cat 61, give a correct, upright image for daytime and terrestrial use. The Binoviewer Complete Package and its 2x Barlow nosepiece let you observe with both eyes.\u003c\/p\u003e","products":[{"product_id":"william-optics-2x-barlow-nosepiece-for-binoviewer","title":"William Optics 2x Barlow Nosepiece for Binoviewer","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides 2x magnification\u003c\/li\u003e\n\u003cli\u003eEnables binoviewers to reach focus in most telescopes\u003c\/li\u003e\n\u003cli\u003eStandard 1.25\" nosepiece format\u003c\/li\u003e\n\u003cli\u003eThreads directly onto the binoviewer body\u003c\/li\u003e\n\u003cli\u003eSolves insufficient back-focus travel issues\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eWilliam Optics 2x Barlow Nosepiece for Binoviewer\u003c\/h2\u003e\n\u003cp\u003eThe William Optics 2x Barlow Nosepiece for Binoviewer is a purpose-built optical corrector designed to solve the single most common obstacle to two-eyed observing: achieving focus. This 1.25\" nosepiece provides the critical 2x optical amplification required to extend your telescope's focal point, allowing it to meet the long light path of a binoviewer.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eAchieve Focus at 2x: The Essential Binoviewer Accessory\u003c\/h3\u003e\n\u003cp\u003eMany telescopes, particularly Newtonians and some refractors, lack the necessary inward focuser travel (back focus) to accommodate the long optical path of a binoviewer. This nosepiece acts as a Barlow lens and optical path corrector, pushing the focal plane outward so your focuser can reach it. The result is a sharp, focused image where one was previously impossible, making this accessory essential for using your binoviewer on a wider range of instruments.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eSecure 1.25\" Thread-In Design for Stability\u003c\/h3\u003e\n\u003cp\u003eUnlike a standard Barlow lens that drops into a focuser, the William Optics 2x Barlow Nosepiece threads directly onto the body of the binoviewer itself, replacing the standard 1.25\" nosepiece. This direct, threaded connection creates a solid and secure optical train, eliminating the potential for sag, flexure, or misalignment that can occur when stacking separate components. This ensures your eyepieces and the binoviewer remain perfectly collimated with the telescope's optical axis.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy do I need a special 2x Barlow Nosepiece for my William Optics binoviewer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA binoviewer has a long optical path due to its internal prisms. Most telescopes don't have enough inward focus travel to compensate, meaning you can't achieve a sharp image. The \u003cstrong\u003eWilliam Optics 2x Barlow Nosepiece\u003c\/strong\u003e extends the telescope's focal point outward, allowing your focuser to reach it. It's an essential corrector for enabling binoviewer use on many telescope designs.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 2x Barlow Nosepiece work with binoviewers from other brands?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile designed for William Optics binoviewers, this 2x Barlow may be compatible with other models that use a standard thread for a removable 1.25\" nosepiece. However, compatibility is not guaranteed, as threading and optical path lengths can vary between manufacturers.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the William Optics 2x Barlow Nosepiece affect views of Jupiter in my 8\" SCT?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAn 8\" SCT already has a long focal length, and this 2x Barlow will double it, providing very high magnification. This is ideal for resolving fine details in Jupiter's cloud bands, the Great Red Spot, and transits of its moons. You will need steady atmospheric seeing conditions to take full advantage of the high power.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the 2x Barlow Nosepiece for deep-sky objects like the Hercules Cluster (M13)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, but with a trade-off. The 2x magnification will make the background sky darker and can help resolve individual stars in the core of a bright globular cluster like M13. However, it will also significantly narrow your field of view and dim the image, making it less suitable for large, faint objects like nebulae or galaxies.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes this William Optics nosepiece thread into the filter threads of my existing nosepiece?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The \u003cstrong\u003eWilliam Optics 2x Barlow Nosepiece\u003c\/strong\u003e is designed to completely replace your binoviewer's existing 1.25\" nosepiece. You must first unthread and remove the standard nosepiece from the binoviewer body before threading this Barlow nosepiece in its place.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the only purpose of the William Optics 2x Barlow Nosepiece to reach focus?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIts primary purpose is to enable focus, but it also functions as a quality 2x Barlow lens. By doubling your magnification, it allows you to achieve the high powers necessary for detailed lunar and planetary observation, effectively expanding the utility of your eyepiece collection when using the binoviewer.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct Name\u003c\/td\u003e\n\u003ctd\u003eWilliam Optics 2x Barlow Nosepiece for Binoviewer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMagnification Factor\u003c\/td\u003e\n\u003ctd\u003e2x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel Size\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eConnection\u003c\/td\u003e\n\u003ctd\u003eDirect thread-on to binoviewer body\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrimary Application\u003c\/td\u003e\n\u003ctd\u003eBinoviewer In-Focus Corrector\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eWilliam Optics 2x Barlow Nosepiece for Binoviewer\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967219331357,"sku":"WO-E-BINO-B2","price":81.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/products\/William-Optics-2x-Barlow-Nosepiece-for-Binoviewer-E-BINO-B2-1__77251.1596133233.1280.1280.jpg?v=1684339279"},{"product_id":"william-optics-binoviewer-complete-package","title":"William Optics Binoviewer Complete Package","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eIncludes two 20mm 66° wide-angle eyepieces\u003c\/li\u003e\n\u003cli\u003eHigh-quality BaK4 prisms with full multi-coatings\u003c\/li\u003e\n\u003cli\u003eLarge 20mm clear prism aperture prevents vignetting\u003c\/li\u003e\n\u003cli\u003eIncludes 1.6x Barlow nosepiece to ensure focus with most telescopes\u003c\/li\u003e\n\u003cli\u003eIndividual helical eyepiece focusing for perfect sharpness\u003c\/li\u003e\n\u003cli\u003eAccepts standard 1.25\" astronomy eyepieces\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eWilliam Optics Binoviewer Complete Package\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Binoviewer package transforms solo eyepiece viewing into an immersive, two-eyed experience, delivering a matched pair of 20mm wide-angle 66° eyepieces for immediate use. Its optical path is built around high-grade BaK4 prisms with a 20mm clear aperture to maximize brightness and eliminate vignetting. This complete set includes a 1.6x Barlow nosepiece, which extends your telescope's focal point to ensure the binoviewer can reach focus in nearly any instrument, from Schmidt-Cassegrains to Newtonians.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e20mm BaK4 Prisms: Bright, High-Contrast Binocular Views\u003c\/h3\u003e\n\u003cp\u003eAt the heart of the William Optics Binoviewer are oversized, fully multi-coated BaK4 prisms. The 20mm clear aperture is critical for passing the full light cone from your telescope to both eyes without clipping the edges of the field, a common issue in binoviewers with smaller prisms. This design preserves the brightness and contrast of your telescope, delivering views that are rich in detail and free of false color.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaK4 Glass:\u003c\/strong\u003e Provides higher refractive index and minimizes internal reflections for a cleaner, higher-contrast image compared to lower-grade prism glass.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully Multi-Coated Optics:\u003c\/strong\u003e Every air-to-glass surface is coated to maximize light transmission, ensuring the view remains bright even after splitting the light path between two eyes.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003ePrecision Mechanics: Individual Focus and Brass Compression Rings\u003c\/h3\u003e\n\u003cp\u003eBuilt for durability and ease of use, the binoviewer body features a white powder-coated finish and large, chromed thumbscrews for easy handling with gloves. Each eyepiece holder incorporates an independent helical focuser, allowing you to precisely compensate for differences between your eyes to achieve a perfectly merged, sharp image. The 1.25\" holders use non-marring brass compression rings to securely grip your eyepieces without scratching the barrels.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eA Complete 66° Viewing System with a 1.6x Barlow\u003c\/h3\u003e\n\u003cp\u003eThis is not just a binoviewer body; it's a complete observing system. William Optics includes a matched pair of 20mm wide-angle eyepieces with a 66° apparent field of view, providing an ideal starting point for lunar, planetary, and deep-sky observation. The critical component for many users is the included 1.6x Barlow nosepiece. Most telescopes, especially Newtonians, lack the back focus required for a binoviewer; this Barlow extends the focal plane outward, guaranteeing you can achieve a sharp image without modifying your telescope.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the purpose of the included 1.6x Barlow with the William Optics Binoviewer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e1.6x Barlow\u003c\/strong\u003e is essential for reaching focus in telescopes with limited back focus, such as most Newtonian reflectors and some refractors. Binoviewers require a long light path, and this Barlow pushes the telescope's focal point outward to meet that requirement. It also provides a moderate increase in magnification.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use my own 1.25\" eyepieces with the William Optics Binoviewer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The William Optics Binoviewer is compatible with most standard 1.25\" eyepieces. For best results, you should use two identical eyepieces (a matched pair) to ensure a perfectly merged and comfortable view. The brass compression rings will hold them securely without damaging their barrels.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy do I need individual eyepiece focus on the WO Binoviewer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIndividual focus adjustment allows you to compensate for differences in vision between your left and right eyes (diopter correction). By focusing each eyepiece separately, you can achieve a single, perfectly sharp image that is comfortable to view for extended periods, reducing eye strain.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the William Optics Binoviewer perform on the Moon and Jupiter with my 8\" SCT?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAn 8\" SCT is an excellent match for this binoviewer. The two-eyed view adds a remarkable sense of depth and dimensionality to lunar craters and mountain ranges. On Jupiter, you'll find it easier to perceive subtle details in the cloud bands and spot the Galilean moons. The included 20mm eyepieces and 1.6x Barlow will provide a high-contrast, comfortable view of both targets.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the William Optics Binoviewer reach focus in my 10\" Dobsonian?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, most likely. Most commercial Dobsonian (Newtonian) telescopes do not have enough inward focuser travel to reach focus with a binoviewer alone. However, this package includes the \u003cstrong\u003e1.6x Barlow nosepiece\u003c\/strong\u003e specifically to solve this problem. By inserting the Barlow, you will almost certainly be able to achieve focus.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eAre the included 20mm eyepieces good for deep-sky objects like the Orion Nebula (M42)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. The 20mm eyepieces provide a moderately low power and a wide 66° field of view, making them excellent for framing larger deep-sky objects like the Orion Nebula (M42), the Andromeda Galaxy (M31), or open clusters like the Pleiades (M45). The binocular view can make these objects appear more three-dimensional against the background sky.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrism Type\u003c\/td\u003e\n\u003ctd\u003eBaK4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrism Clear Aperture\u003c\/td\u003e\n\u003ctd\u003e20mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Coatings\u003c\/td\u003e\n\u003ctd\u003eFully Multi-Coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEyepiece Compatibility\u003c\/td\u003e\n\u003ctd\u003e1.25\" Barrels\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEyepiece Holders\u003c\/td\u003e\n\u003ctd\u003eBrass Compression Rings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocusing\u003c\/td\u003e\n\u003ctd\u003eIndividual Helical Diopter Adjustment\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIncluded Eyepieces\u003c\/td\u003e\n\u003ctd\u003e2x 20mm Wide Angle\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEyepiece Apparent Field\u003c\/td\u003e\n\u003ctd\u003e66°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIncluded Barlow\u003c\/td\u003e\n\u003ctd\u003e1.6x Magnification Nosepiece\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFinish\u003c\/td\u003e\n\u003ctd\u003eWhite Powder Coat\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eWilliam Optics Binoviewer Body\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e20mm WA 66° Eyepieces\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 2\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e1.6x Barlow Nosepiece\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eProtective Caps\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 3\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003ePresentation Gift Box\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967219364125,"sku":"WO-E-BINO-P","price":509.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-Binoviewer-Complete-Package-E-BINO-P-1__33057.1596133235.1280.1280.jpg?v=1684339281"},{"product_id":"william-optics-99-dielectric-dura-bright-diagonal-1-25","title":"William Optics 99% Dielectric Dura Bright Diagonal - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e1.25\" Barrel Diameter\u003c\/li\u003e\n\u003cli\u003e99% Dielectric Coated Mirror\u003c\/li\u003e\n\u003cli\u003e1\/12λ Mirror Surface Accuracy\u003c\/li\u003e\n\u003cli\u003e12mm Thick Mirror Substrate\u003c\/li\u003e\n\u003cli\u003e100% Real Carbon Fiber Side Plates\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section-center\"\u003e\n      \u003ch2\u003eWilliam Optics 99% Dielectric Dura Bright Diagonal - 1.25\"\u003c\/h2\u003e\n      \u003cp\u003eThe William Optics 1.25\" Dura-Bright Diagonal delivers maximum image brightness and contrast through its 99% reflective dielectric coatings and a precision 1\/12λ mirror. Built on a thermally stable 12mm thick substrate and housed in a patented, permanently aligned chassis with 100% real carbon fiber plates, this diagonal ensures your telescope's optical path remains perfect from the first day of use.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eThe 1\/12λ Mirror: 99% Reflectivity for Maximum Contrast\u003c\/h3\u003e\n      \u003cp\u003eA star diagonal is a critical element in the optical chain, and the Dura-Bright is built around a laboratory-grade mirror. The 12mm thick substrate provides exceptional thermal and mechanical stability, while the surface is polished to a 1\/12λ wave accuracy, preserving the sharpness produced by your telescope's objective. Dielectric coatings provide 99% reflectivity, noticeably brightening the image and increasing contrast on faint deep-sky targets and subtle planetary details like the cloud bands of Jupiter.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003ePatented Design: 100% Carbon Fiber and Permanent Alignment\u003c\/h3\u003e\n      \u003cp\u003eWilliam Optics rejects the idea that a diagonal should ever need user adjustment. Where competing designs use collimation screws—an admission of potential mechanical flexure—the Dura-Bright employs a patented, fixed housing that guarantees perfect alignment for life. The 100% real carbon fiber side plates provide extreme rigidity and a touch of class, while internal baffles eliminate stray light for blacker backgrounds.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eCompression Rings:\u003c\/strong\u003e Both the 1.25\" eyepiece holder and adapter use brass compression rings to securely grip your eyepieces without marring their barrels.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eGlove-Friendly Screws:\u003c\/strong\u003e Large, knurled thumbscrews are easy to operate even on cold nights while wearing gloves.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eInternal Safety Stop:\u003c\/strong\u003e A machined stop prevents long 1.25\" eyepiece barrels from ever making contact with the diagonal's mirror surface.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n    \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eDura-Bright vs. Standard Diagonals: A 5% Gain in Reflectivity\u003c\/h3\u003e\n      \u003cp\u003eCompared to standard aluminum or silver diagonals that typically offer 90-94% reflectivity, the Dura-Bright's 99% dielectric mirror transmits significantly more light to your eye. This 5% or greater increase in light throughput makes a visible difference when observing at the limits of your telescope, rendering faint galaxies brighter and globular clusters more resolved. The dielectric coatings are also far more durable than standard coatings, ensuring this brightness advantage does not degrade over years of use and cleaning.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the benefit of the William Optics Dura-Bright Diagonal's 99% reflectivity?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe \u003cstrong\u003e99% reflectivity\u003c\/strong\u003e from the dielectric coatings ensures the maximum amount of light from your telescope reaches the eyepiece. This results in brighter images and higher contrast compared to standard diagonals (which are often 90-94% reflective), making faint objects easier to see and planetary details more distinct.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill the 1.25\" Dura-Bright Diagonal improve my views of Jupiter and Saturn?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes. The combination of high reflectivity and the \u003cstrong\u003e1\/12λ mirror surface\u003c\/strong\u003e preserves the finest details your telescope can resolve. This allows for sharper views of Jupiter’s Great Red Spot, subtle cloud bands, and the Cassini Division in Saturn’s rings, especially when compared to a lower-quality stock diagonal.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhy doesn't the William Optics Dura-Bright Diagonal have collimation screws?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eWilliam Optics considers adjustable alignment systems a sign of poor mechanical design. The Dura-Bright uses a \u003cstrong\u003epatented, rigid, non-adjustable housing\u003c\/strong\u003e to guarantee perfect alignment from the factory that will not shift over time. This ensures consistent, optimal performance without the need for user adjustment.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the carbon fiber on the Dura-Bright Diagonal just for aesthetics?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eWhile the \u003cstrong\u003e100% real carbon fiber\u003c\/strong\u003e side plates are visually striking, their primary purpose is structural. Carbon fiber is exceptionally strong, rigid, and lightweight, contributing to the diagonal's robust, permanently aligned construction.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I use filters with the William Optics 1.25\" Dura-Bright Diagonal?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYou attach standard \u003cstrong\u003e1.25\" threaded filters\u003c\/strong\u003e directly to the barrel of your 1.25\" eyepieces before inserting them into the diagonal. The diagonal itself does not have filter threads.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Dura-Bright Diagonal perform for splitting double stars like Albireo in my 80mm refractor?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eFor a task like splitting the colorful components of Albireo (Beta Cygni), the Dura-Bright excels. Its high-precision \u003cstrong\u003e1\/12λ mirror\u003c\/strong\u003e prevents any degradation of the star's Airy disk, ensuring the tightest possible stars. The high light transmission also helps maintain the brightness and rich color contrast of the binary pair in a smaller 80mm aperture.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003ctable class=\"DAV-specifications\"\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eDiagonal Size\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eViewing Angle\u003c\/td\u003e\n\u003ctd\u003e90°\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eReflectivity\u003c\/td\u003e\n\u003ctd\u003e99%\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMirror Coatings\u003c\/td\u003e\n\u003ctd\u003eDielectric\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMirror Surface Accuracy\u003c\/td\u003e\n\u003ctd\u003e1\/12λ\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMirror Thickness\u003c\/td\u003e\n\u003ctd\u003e12mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSide Plate Material\u003c\/td\u003e\n\u003ctd\u003e100% Real Carbon Fiber\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eAlignment\u003c\/td\u003e\n\u003ctd\u003ePatented Non-Adjustable Design\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eEyepiece Holder\u003c\/td\u003e\n\u003ctd\u003eBrass Compression Ring\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBaffling\u003c\/td\u003e\n\u003ctd\u003eInternal Anti-Reflection Baffling\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSafety Feature\u003c\/td\u003e\n\u003ctd\u003eInternal Stop for Eyepiece Barrels\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003e1.25\" Dura Bright Dielectric Diagonal\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eDust Caps\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 2\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967224181021,"sku":"WO-D-125D-C-DB","price":190.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/products\/William-Optics-Dura-Bright-Dielectric-Diagonal-1-25-inch-D-125D-C-DB-1__99095.1596133245.1280.1280.jpg?v=1684339363"},{"product_id":"william-optics-99-dielectric-dura-bright-diagonal-2","title":"William Optics 99% Dielectric Dura Bright Diagonal - 2\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e2\" Barrel with 90° Viewing Angle\u003c\/li\u003e\n\u003cli\u003e99% Reflectivity Dielectric Coatings\u003c\/li\u003e\n\u003cli\u003e1\/12th Wave Precision Polished Mirror\u003c\/li\u003e\n\u003cli\u003e12mm Thick Mirror Substrate for Thermal Stability\u003c\/li\u003e\n\u003cli\u003e100% Real Carbon Fiber Side Plates\u003c\/li\u003e\n\u003cli\u003eIncludes 2\" to 1.25\" Adapter with Compression Ring\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eWilliam Optics 99% Dielectric Dura Bright Diagonal - 2\"\u003c\/h2\u003e\n\u003cp\u003eThe William Optics 2\" Dura-Bright Diagonal is built around a 12mm thick, 1\/12th wave mirror substrate with 99% reflective dielectric coatings, delivering maximum light transmission for critical observations. Its 90° mirror design is housed in a precision-machined body featuring 100% real carbon fiber side plates, and it includes a 2\" to 1.25\" adapter to accommodate your entire eyepiece collection.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e99% Reflectivity from a 1\/12th Wave Dielectric Mirror\u003c\/h3\u003e\n\u003cp\u003eAt the heart of the Dura-Bright is a mirror polished to a 1\/12th wave accuracy, ensuring that the image remains free of optical errors. This precision flat is supported by a 12mm thick substrate for excellent thermal stability, preventing image shift during temperature changes. The mirror's dielectric coatings achieve 99% reflectivity, providing noticeably brighter images and higher contrast when observing fine details on Jupiter's cloud bands or splitting close binary stars.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCarbon Fiber Build with Non-Marring Compression Rings\u003c\/h3\u003e\n\u003cp\u003eThe diagonal's body is distinguished by 100% real carbon fiber side plates, reducing weight and adding structural rigidity. Both the 2\" diagonal barrel and the included 1.25\" adapter use brass compression rings, which secure your eyepieces firmly without scratching or marring their barrels. Internally, anti-reflection baffling eliminates stray light, while a safety stop prevents 2\" eyepiece barrels from ever contacting the mirror surface.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003ePatented Design: Permanently Aligned for Life\u003c\/h3\u003e\n\u003cp\u003eUnlike diagonals that require periodic adjustment, the William Optics Dura-Bright is engineered to hold its collimation permanently. A non-adjustable design is a testament to its mechanical integrity; the diagonal is CNC-machined from a solid block of aluminum to guarantee its optical axis remains perfectly aligned from the first day of use. This robust construction ensures your telescope's optical train remains precise, session after session.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of the William Optics Dura-Bright's 99% dielectric coating?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e99% dielectric coating\u003c\/strong\u003e ensures that virtually all light gathered by your telescope reaches your eyepiece. This results in brighter, higher-contrast images compared to standard aluminum or silver coatings, which is especially critical for observing faint planetary details, deep-sky objects, and the subtle color differences in stars.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy doesn't the William Optics Dura-Bright diagonal have collimation screws?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe absence of collimation screws is a design feature, not a limitation. William Optics builds the Dura-Bright diagonal with such high mechanical precision that it is guaranteed to hold its alignment permanently. Diagonals that offer adjustments often do so because their construction is less robust and can shift over time; the Dura-Bright's patented, solid design eliminates this possibility.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Dura-Bright diagonal scratch my eyepiece barrels?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. Both the main 2\" holder and the included 1.25\" adapter use \u003cstrong\u003ebrass compression rings\u003c\/strong\u003e. Unlike simple lock screws that dig into the eyepiece barrel, a compression ring provides a secure, even grip around the entire barrel, preventing any cosmetic damage or marring.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 12mm thick mirror in the Dura-Bright help when observing Jupiter with my FLT-132?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e12mm thick mirror substrate\u003c\/strong\u003e provides superior thermal stability. When observing an object like Jupiter for an extended period, especially as your telescope adjusts to ambient temperature, a thinner mirror could slightly deform and soften the image. The Dura-Bright's thick mirror resists these changes, ensuring your view of the Great Red Spot and its cloud bands remains sharp and stable all night.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use 1.25\" eyepieces with the 2\" William Optics Dura-Bright diagonal?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, absolutely. The diagonal comes with a high-quality \u003cstrong\u003e2\" to 1.25\" adapter\u003c\/strong\u003e. This adapter also features a compression ring, so your 1.25\" eyepieces are held just as securely and safely as your 2\" eyepieces.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Dura-Bright a good choice for splitting close double stars like Epsilon Lyrae with a GT102?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, it's an excellent choice. Splitting tight doubles like the \"Double Double\" Epsilon Lyrae requires maximum image contrast and sharpness. The Dura-Bright's \u003cstrong\u003e1\/12th wave mirror\u003c\/strong\u003e and \u003cstrong\u003e99% reflectivity coatings\u003c\/strong\u003e preserve the delicate Airy disk and diffraction rings of the stars, making it easier to achieve a clean separation at high magnification with a high-end refractor like the GT102.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel Size\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eViewing Angle\u003c\/td\u003e\n\u003ctd\u003e90°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMirror Type\u003c\/td\u003e\n\u003ctd\u003eDura-Bright Dielectric\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReflectivity\u003c\/td\u003e\n\u003ctd\u003e99%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMirror Substrate Thickness\u003c\/td\u003e\n\u003ctd\u003e12mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMirror Flatness\u003c\/td\u003e\n\u003ctd\u003e1\/12th wave\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSide Plate Material\u003c\/td\u003e\n\u003ctd\u003e100% Real Carbon Fiber\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eClamping Mechanism\u003c\/td\u003e\n\u003ctd\u003eBrass Compression Rings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBaffling\u003c\/td\u003e\n\u003ctd\u003eInternal Anti-Reflection Baffling\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSafety Feature\u003c\/td\u003e\n\u003ctd\u003eInternal Barrel Stop\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAdapter Included\u003c\/td\u003e\n\u003ctd\u003e2\" to 1.25\" with Compression Ring\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eWilliam Optics 2\" 99% Dielectric Dura Bright Diagonal\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e2\" to 1.25\" Eyepiece Adapter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967224213789,"sku":"WO-D-DIG2D-C-DB","price":228.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-2-inch-Durabright-CF-Plate-D-DIG2D-C-DB-T-1__49229.1642255347.1280.1280.jpg?v=1684339370"},{"product_id":"william-optics-45-erecting-prism-1-25","title":"William Optics 45° Erecting Prism - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides a fully corrected image (upright and left-right correct)\u003c\/li\u003e\n\u003cli\u003eComfortable 45° viewing angle for terrestrial observation\u003c\/li\u003e\n\u003cli\u003eFits standard 1.25\" focusers and accepts 1.25\" eyepieces\u003c\/li\u003e\n\u003cli\u003eHigh-quality BAK7 prism with anti-reflection coatings\u003c\/li\u003e\n\u003cli\u003eFeatures a non-marring brass compression ring to protect eyepieces\u003c\/li\u003e\n\u003cli\u003eDurable, internally baffled black-anodized aluminum body\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eWilliam Optics 45° Erecting Prism - 1.25\"\u003c\/h2\u003e\n\u003cp\u003eThe William Optics 45° Erecting Prism transforms any astronomical telescope with a 1.25\" focuser into a powerful terrestrial scope for daytime viewing. It reorients the standard inverted and reversed image, delivering a view that is fully upright and corrected left-to-right, just as your eyes see it naturally. With its high-quality BAK7 prism and anti-reflection coatings, this diagonal provides the bright, high-contrast images necessary for birdwatching, landscape viewing, or maritime observation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eFrom Astronomical to Terrestrial: A Fully Corrected 1.25\" View\u003c\/h3\u003e\n\u003cp\u003eA standard telescope view is upside-down and backwards, which is disorienting for observing anything on Earth. This 1.25\" erecting prism solves that problem completely. It provides a \"correct-image\" orientation, making it intuitive to follow moving targets like birds in flight or boats on the water.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eBAK7 Prism Optics: Bright, High-Contrast Daytime Images\u003c\/h3\u003e\n\u003cp\u003eAt the heart of this diagonal is a large, high-quality BAK7 prism. Paired with anti-reflection coatings, it maximizes light throughput for exceptionally bright views. To ensure high contrast and prevent washed-out images, the interior of the aluminum housing is fully blackened and baffled to eliminate stray light reflections before they reach your eyepiece.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eSecure by Design: Anodized Aluminum and a Brass Compression Ring\u003c\/h3\u003e\n\u003cp\u003eThe William Optics erecting prism is built for durability and ease of use. The body is machined from black-anodized aluminum, and the 1.25\" eyepiece holder features a non-marring brass compression ring. This design ensures your eyepiece barrels are held securely without the scratches and gouges caused by single-thumbscrew systems. Large, chromed thumbscrews make it easy to secure your eyepieces, even when wearing gloves.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e45° vs. 90° Diagonals: Choosing the Right Tool for the Job\u003c\/h3\u003e\n\u003cp\u003eWhile a standard 90° star diagonal is ideal for astronomy, its image is still reversed left-to-right. This 45° erecting prism provides a fully correct image, making it superior for terrestrial use. The 45° angle is also more comfortable for viewing subjects on or near the horizon, whereas a 90° angle becomes awkward. For daytime use, the 45° erecting prism is the correct choice; for nighttime astronomical viewing, a 90° star diagonal remains the standard.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy do I need the William Optics 45° Erecting Prism for daytime viewing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAstronomical telescopes naturally produce an image that is upside-down and backward. While this doesn't matter for stars, it makes viewing terrestrial objects impossible to follow. The \u003cstrong\u003eWilliam Optics 45° Erecting Prism\u003c\/strong\u003e corrects the image to be both upright and normal left-to-right, making your telescope function like a high-power spotting scope.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this William Optics prism work with my Schmidt-Cassegrain or reflector telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis prism is primarily designed for refractors and Maksutov-Cassegrain telescopes. While it will fit in the 1.25\" focuser of a Schmidt-Cassegrain (SCT) or Newtonian reflector, you may not have enough focuser travel to reach a sharp image. Refractors are generally the best match for this type of diagonal.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the difference between this 45° erecting prism and a standard 90° star diagonal?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThere are two key differences:\n\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eImage Orientation:\u003c\/strong\u003e A 90° star diagonal corrects the up\/down orientation but leaves the image mirrored left-to-right. This 45° prism corrects \u003cstrong\u003eboth\u003c\/strong\u003e axes, providing a fully correct image.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eViewing Angle:\u003c\/strong\u003e The 45° angle is more comfortable for looking at objects on the horizon. The 90° angle is better for looking high into the night sky.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does the brass compression ring on the WO-D-EP125 do?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003ebrass compression ring\u003c\/strong\u003e is a soft metal ring inside the eyepiece holder that tightens evenly around your eyepiece barrel when you turn the thumbscrew. This provides a secure, centered grip without scratching or marring the eyepiece barrel, unlike a simple set screw that digs into one point.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the William Optics 45° prism for birdwatching with my 80mm refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. An 80mm refractor paired with this erecting prism makes an excellent, high-magnification setup for birdwatching. The fully corrected image allows you to easily track birds, and the optical quality of the BAK7 prism ensures you'll see fine feather detail with bright, clear views.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this prism affect focusing on my telescope when viewing ships from my balcony?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, all diagonals change the focus point of a telescope. The William Optics 45° prism will require you to move the focuser \"out\" (away from the telescope tube) to reach focus compared to viewing without a diagonal. Most refractors have ample focuser travel to accommodate this without any issue.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiagonal Type\u003c\/td\u003e\n\u003ctd\u003eErecting Prism\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eViewing Angle\u003c\/td\u003e\n\u003ctd\u003e45°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel Size\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Orientation\u003c\/td\u003e\n\u003ctd\u003eFully Corrected (Upright \u0026amp; Left-Right Correct)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrism Material\u003c\/td\u003e\n\u003ctd\u003eBAK7\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Coatings\u003c\/td\u003e\n\u003ctd\u003eAnti-Reflection Coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBody Construction\u003c\/td\u003e\n\u003ctd\u003eBlack Anodized Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInterior\u003c\/td\u003e\n\u003ctd\u003eBaffled and Blackened\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEyepiece Holder\u003c\/td\u003e\n\u003ctd\u003e1.25\" with Brass Compression Ring\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eWilliam Optics 45° Erecting Prism - 1.25\"\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967224246557,"sku":"WO-D-EP125","price":152.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/products\/William-Optics-45-degree-Erecting-Prism-1-25-inch-D-EP125-1__94579.1596133249.1280.1280.jpg?v=1684339395"},{"product_id":"william-optics-redcat-erecting-prism-1-25-silver-version","title":"William Optics RedCat WIFD Erecting Prism - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eConverts Astronomical Telescopes for Terrestrial Viewing\u003c\/li\u003e\n\u003cli\u003e90-Degree Viewing Angle\u003c\/li\u003e\n\u003cli\u003eAccepts Standard 1.25\" Eyepieces\u003c\/li\u003e\n\u003cli\u003eAnti-Reflection Coated BAK7 Prism\u003c\/li\u003e\n\u003cli\u003eCNC-Machined 6061T Aluminum Housing\u003c\/li\u003e\n\u003cli\u003eInternally Baffled and Matte Blackened to Maximize Contrast\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eWilliam Optics RedCat WIFD Erecting Prism - 1.25\"\u003c\/h2\u003e\n\u003cp\u003eThe William Optics RedCat WIFD Erecting Prism transforms your astronomical telescope into a powerful daytime spotting scope with its 90-degree, correct-image light path. Designed to fit any standard 1.25-inch focuser, this prism uses an anti-reflection coated BAK7 prism to deliver bright, sharp, and correctly oriented views, making it ideal for terrestrial observation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCorrect-Image Daytime Viewing with a 90-Degree BAK7 Prism\u003c\/h3\u003e\n\u003cp\u003eAn astronomical telescope naturally produces an inverted or mirror-reversed image, which is disorienting for terrestrial subjects. This 90-degree erecting prism corrects the image orientation both vertically and horizontally, allowing you to view ships on the horizon, wildlife, or distant landscapes as you would with your own eyes. The internal BAK7 prism is anti-reflection coated to ensure high light transmission for a clear and vibrant image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCNC-Machined 6061T Aluminum Construction\u003c\/h3\u003e\n\u003cp\u003eReflecting William Optics' commitment to quality, the entire prism housing is precision CNC-machined from a solid block of 6061T aluminum. The interior is matte blackened and threaded to absorb stray light, preventing internal reflections from reducing image contrast. Finished in the distinctive William Optics red anodizing, this erecting prism is built to provide durable, high-fidelity performance that perfectly complements the RedCat 51 WIFD and other premium refractors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does the William Optics 1.25\" Erecting Prism do for my RedCat 51?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis prism converts your RedCat 51, or any telescope with a 1.25\" focuser, into a terrestrial spotting scope. It corrects the inverted and reversed image produced by the telescope, providing a view that is correctly oriented for daytime activities like birdwatching, nature observation, or surveillance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this William Optics prism for astronomy at night?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile you can use it for casual stargazing, an erecting prism is not ideal for critical astronomical observation. The complex light path required to correct the image can introduce minor aberrations and light loss compared to a high-quality mirror or Amici prism star diagonal. For the best possible astronomical views, a dedicated star diagonal is recommended.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will this 90-degree prism help with birdwatching using my RedCat 51 telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eFor birdwatching, having a correctly oriented image is essential for tracking moving subjects. This 90-degree prism ensures that when you move the telescope up, the view moves up, and when you move it left, the view moves left. This intuitive control allows you to follow birds in flight or locate them in dense foliage much more easily than with an astronomical diagonal.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the difference between this erecting prism and a standard star diagonal?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA standard \u003cstrong\u003estar diagonal\u003c\/strong\u003e corrects the image vertically but leaves it mirror-reversed (left-to-right). This is acceptable for astronomy but confusing for terrestrial viewing. An \u003cstrong\u003eerecting prism\u003c\/strong\u003e, like this one, corrects the image on both axes, providing a fully correct, daytime-friendly view.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI want to use my William Optics RedCat 51 for plane spotting. Is this the right accessory?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this is an excellent accessory for plane spotting. The fully corrected image allows you to track aircraft across the sky intuitively, and the 90-degree angle provides a comfortable viewing position when the telescope is pointed at high altitudes. The high-contrast optics will help you resolve details and airline liveries clearly.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the William Optics Erecting Prism compatible with non-William Optics telescopes?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. This erecting prism uses a standard 1.25\" barrel, making it compatible with any telescope that accepts 1.25\" eyepieces and diagonals. You will just need to ensure your focuser has enough travel to reach focus with the prism in the optical train.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eErecting Prism\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eViewing Angle\u003c\/td\u003e\n\u003ctd\u003e90-Degree\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel Size\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrism Material\u003c\/td\u003e\n\u003ctd\u003eBAK7\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eAnti-Reflection Coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHousing Material\u003c\/td\u003e\n\u003ctd\u003eCNC-Machined 6061T Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFinish\u003c\/td\u003e\n\u003ctd\u003eRed Anodized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInterior\u003c\/td\u003e\n\u003ctd\u003eMatte Blackened \u0026amp; Threaded\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrimary Use\u003c\/td\u003e\n\u003ctd\u003eDaytime Terrestrial Observation\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eDesigned for RedCat 51 WIFD, compatible with all 1.25\" focusers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eWilliam Optics RedCat WIFD Erecting Prism - 1.25\"\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e1.25\" Dust Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eEyepiece Dust Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967224443165,"sku":"WO-D-EP90-125-RC51III","price":219.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-RedCat-Erecting-Prism-1-25-inch-Silver-Version-D-EP90-125-RC51-SL-1__00946.1596133250.1280.1280.jpg?v=1684339157"},{"product_id":"william-optics-90-erect-prism-1-25","title":"William Optics 90° Erect Prism - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides a fully corrected, upright, and non-reversed image\u003c\/li\u003e\n\u003cli\u003eDesigned for 1.25\" focusers and eyepieces\u003c\/li\u003e\n\u003cli\u003e90° viewing angle for comfortable observing\u003c\/li\u003e\n\u003cli\u003eIntegrated helical focuser for fine adjustments\u003c\/li\u003e\n\u003cli\u003eThreaded to accept standard 1.25\" filters\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eWilliam Optics 90° Erect Prism - 1.25\"\u003c\/h2\u003e\n\u003cp\u003eThe William Optics 90° Erect Prism corrects the image orientation in any 1.25\" focuser, making your astronomical refractor a superb terrestrial telescope. This BAK7 prism design provides an upright, non-reversed view at a comfortable 90° angle, a critical feature for daytime observation that standard mirror diagonals cannot offer.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eA 90° Erecting Prism for Correct-Image Views\u003c\/h3\u003e\n\u003cp\u003eA standard astronomical telescope inverts the image. This William Optics diagonal uses a high-accuracy BAK7 erecting prism to flip the image both vertically and horizontally, producing a view that matches what you see with your naked eye. This is essential for birdwatching, landscape viewing, or any terrestrial application where a true-to-life orientation is required.\u003c\/p\u003e\n\u003cp\u003eThe prism features anti-reflection coatings to maximize light transmission, while the interior of the housing is matte blackened to eliminate stray light reflections. The result is a high-contrast image that makes this diagonal a perfect match for premium refractors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eHelical Focuser and 1.25\" Filter Threads\u003c\/h3\u003e\n\u003cp\u003eA key feature of this diagonal is the integrated helical focuser on the eyepiece holder. This mechanism allows for fine, precise focus adjustments without touching your telescope's main focuser, which is ideal for achieving critical sharpness at high magnification or for matching focus between different eyepieces.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurable Construction:\u003c\/strong\u003e The body is machined from black anodized aluminum, ensuring a rigid and durable connection in your optical train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilter Compatibility:\u003c\/strong\u003e The 1.25\" nosepiece is threaded to accept standard 1.25\" filters, allowing you to easily add a moon filter or color filter for planetary viewing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eWilliam Optics Erecting Prism vs. Standard Mirror Diagonals\u003c\/h3\u003e\n\u003cp\u003eFor astronomical use, a high-end dielectric mirror diagonal may offer marginally higher light transmission, making it preferable for imaging faint deep-sky objects. However, a mirror diagonal only corrects the up-down axis, leaving the image reversed left-to-right.\u003c\/p\u003e\n\u003cp\u003eFor any application where image orientation matters, the erecting prism is the superior tool. Whether you're tracking a ship on the horizon or using your telescope for public outreach, the William Optics 90° Erect Prism delivers an intuitive, correctly oriented view that mirrors reality.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy do I need the William Optics 90° Erect Prism for daytime viewing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eStandard astronomical diagonals produce an image that is either upside-down or mirrored left-to-right. The \u003cstrong\u003eWilliam Optics 90° Erect Prism\u003c\/strong\u003e corrects the image on both axes, giving you a fully upright and non-reversed view, just like a pair of binoculars. This is essential for terrestrial applications like birdwatching or landscape observation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the helical focuser on the William Optics Erect Prism work?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe top barrel of the diagonal, where you insert the eyepiece, can be rotated. This rotation moves the eyepiece up and down with very fine precision, allowing you to make small, critical focus adjustments. It's especially useful for fine-tuning focus at high power or when swapping eyepieces that are not perfectly parfocal.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the William Optics 1.25\" Erect Prism work with my Schmidt-Cassegrain telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this prism diagonal will work perfectly with any Schmidt-Cassegrain (SCT), Maksutov-Cassegrain, or refractor that uses a 1.25\" visual back or focuser. It provides a comfortable 90° viewing angle and a correctly oriented image, making it a versatile accessory for any compatible telescope.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use 1.25\" filters like a moon filter with this William Optics prism?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The 1.25\" nosepiece that inserts into the telescope's focuser is threaded to accept all standard 1.25\" filters. You can easily attach a moon filter, planetary color filters, or a light pollution filter.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat's the difference between this William Optics Erecting Prism and a mirror diagonal?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAn \u003cstrong\u003eErecting Prism\u003c\/strong\u003e provides a fully corrected image (upright and not reversed left-to-right), which is ideal for daytime use. A \u003cstrong\u003eMirror Diagonal\u003c\/strong\u003e provides an image that is upright but still reversed left-to-right. While a high-quality mirror may have slightly better light transmission for deep-sky astronomy, the prism is the correct choice for terrestrial viewing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs this prism a good choice for observing planets like Jupiter in my premium refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile this prism will certainly show you planets, a high-quality dielectric mirror diagonal is generally recommended for critical planetary observation. Mirror diagonals tend to have slightly higher light throughput and introduce fewer optical artifacts than a prism, preserving the maximum possible contrast for viewing details like the cloud bands of Jupiter (M42) or the Cassini Division in Saturn's rings.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel Size\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eViewing Angle\u003c\/td\u003e\n\u003ctd\u003e90°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Orientation\u003c\/td\u003e\n\u003ctd\u003eErect (Upright \u0026amp; Non-Reversed)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrism Type\u003c\/td\u003e\n\u003ctd\u003eBAK7\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eAnti-Reflection Coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eIntegrated Helical Focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBody Material\u003c\/td\u003e\n\u003ctd\u003eBlack Anodized Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternal Baffling\u003c\/td\u003e\n\u003ctd\u003eMatte Blackened\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Threads\u003c\/td\u003e\n\u003ctd\u003eYes (1.25\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eWilliam Optics 90° Erect Prism - 1.25\"\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967224803613,"sku":"WO-D-EP90-125II","price":160.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-90-degree-Erect-Prism-1-25-inch-D-EP90-125II-1__05101.1596133252.1280.1280.jpg?v=1684339397"},{"product_id":"william-optics-d-dig2d-c-db-sct","title":"William Optics 2\" 90° Dura Bright Dielectric Diagonal for SCT threaded Scope","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eEnables use of 2-inch eyepieces for wide-field views\u003c\/li\u003e\n\u003cli\u003e90° viewing angle for comfortable observing at the zenith\u003c\/li\u003e\n\u003cli\u003eDura-Bright dielectric coatings for superior light transmission and durability\u003c\/li\u003e\n\u003cli\u003eThreads directly to the rear cell of SCT-threaded telescopes\u003c\/li\u003e\n\u003cli\u003eReduces mechanical flexure compared to standard slip-fit diagonals\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section-center\"\u003e\n      \u003ch2\u003e2\" 90° Dura Bright Dielectric Diagonal for SCT threaded Scope\u003c\/h2\u003e\n      \u003cp\u003eThis 2\" 90° Dura Bright Dielectric Diagonal is an essential upgrade for any Schmidt-Cassegrain telescope owner looking to maximize both optical throughput and mechanical stability. By threading directly onto your SCT's rear cell, it creates a solid, flex-free connection ideal for heavy 2-inch eyepieces and imaging equipment. The highly reflective and durable dielectric coatings ensure that the maximum amount of light from your telescope's optics reaches your eye, delivering brighter images and improved contrast on faint deep-sky objects.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eThe Stability of a Direct SCT Thread-On Connection\u003c\/h3\u003e\n      \u003cp\u003eUnlike standard diagonals that require a visual back and use a slip-fit compression ring, this model threads directly onto the rear port of most Schmidt-Cassegrain telescopes. This single, solid connection eliminates a common source of mechanical sag and potential misalignment, which is critical when using heavy, wide-field 2-inch eyepieces or a camera. Your optical train remains perfectly collinear, preserving the sharp focus your SCT is designed to deliver.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eDura-Bright Dielectric Coatings for Maximum Reflectivity\u003c\/h3\u003e\n      \u003cp\u003eThe \"Dura-Bright\" mirror features advanced dielectric coatings, which offer two key advantages over standard aluminum or silver coatings. First, they provide extremely high reflectivity across the visual spectrum, transmitting more light to the eyepiece for visibly brighter images. Second, these multi-layer coatings are far more durable and resistant to environmental degradation, ensuring your diagonal maintains its peak optical clarity for years of use without tarnishing.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n    \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eUnlocking Wide-Field Views with the 2-Inch Format\u003c\/h3\u003e\n      \u003cp\u003eThe primary reason to upgrade to a 2-inch diagonal is to gain access to the widest possible true fields of view your telescope can produce. By accommodating 2-inch eyepieces, this diagonal transforms your SCT into a capable instrument for sweeping the Milky Way and framing large celestial objects like the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000) in a single view.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eSCT Thread-On vs. Slip-Fit Diagonals: Why Rigidity Matters\u003c\/h3\u003e\n      \u003cp\u003eFor an SCT owner, the choice between a thread-on and a slip-fit diagonal comes down to stability. While a slip-fit diagonal offers rotational convenience, it can also introduce tilt or sag, especially under the load of a heavy eyepiece like a Tele Vue Nagler or Ethos.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eThread-On Advantage:\u003c\/strong\u003e By becoming a rigid extension of the optical tube, a thread-on diagonal like this Dura Bright model maintains perfect alignment. This prevents focus shift and ensures that stars at the edge of the field remain as sharp as your telescope's optics will allow.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eSlip-Fit Limitation:\u003c\/strong\u003e The small amount of play in a slip-fit connection can be enough to slightly degrade image sharpness, an issue that becomes more apparent during high-magnification planetary viewing or astrophotography.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhy should I upgrade to this 2\" Dura Bright SCT Diagonal from my stock 1.25\" diagonal?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eUpgrading to this 2\" diagonal offers three major improvements. You gain access to \u003cstrong\u003ewide-field 2-inch eyepieces\u003c\/strong\u003e, your views will be noticeably \u003cstrong\u003ebrighter due to the dielectric coatings\u003c\/strong\u003e, and the \u003cstrong\u003edirect SCT thread connection provides a more rigid and stable\u003c\/strong\u003e optical path than the standard visual back and slip-fit diagonal combination.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the main advantage of a \"dielectric\" diagonal?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eA dielectric diagonal uses dozens of micro-thin layers of optical coatings to achieve extremely high reflectivity. This means more light is sent to your eyepiece, making faint objects easier to see. These coatings are also incredibly durable and resistant to aging, so the mirror will not tarnish or lose reflectivity over time like a standard aluminum mirror can.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 2\" Dura Bright diagonal help me see faint objects like the Veil Nebula (NGC 6960) with my 8\" SCT?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes. The combination of using a 2-inch, low-power eyepiece and the high-reflectivity dielectric coatings is ideal for observing large, faint objects like the Veil Nebula. The wider field of view helps you frame the nebula, and the increased light transmission makes it appear brighter against the background sky, especially when paired with a UHC or O-III filter.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow does this Dura Bright diagonal improve views of open clusters like the Pleiades (M45) in my Celestron 11\" SCT?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eA large SCT like an 11\" has a long focal length, making it difficult to fit large open clusters like the Pleiades into a single field of view with 1.25\" eyepieces. This 2\" diagonal allows you to use long focal length 2\" eyepieces, reducing the magnification and expanding your true field of view to frame the entire cluster beautifully.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the direct-thread connection of this SCT diagonal prevent my eyepiece from rotating?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, the diagonal body itself is fixed in place once threaded onto the telescope. However, the eyepiece holder on the diagonal typically uses a non-marring compression ring that allows you to rotate the eyepiece to the most comfortable viewing orientation without loosening the diagonal itself.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this Dura Bright SCT Diagonal on my refractor or Newtonian telescope?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eNo, not directly. This diagonal is designed specifically with SCT threads to attach to the rear cell of a Schmidt-Cassegrain or Maksutov-Cassegrain telescope. It does not have a 2\" nosepiece for use in a standard refractor or Newtonian focuser.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003ctable class=\"DAV-specifications\"\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSpecifications\u003c\/td\u003e\n\u003ctd\u003eNo specifications available for this product.\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eBox Contents\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003eBox contents have not been specified by the manufacturer.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\n\u003cli\u003e\n\u003cp\u003eWarranty information is not available for this product.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":52853691613469,"sku":"WO-D-DIG2D-C-DB-SCT","price":286.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WilliamOptics-2-90-Dura-Bright-Dielectric-Diagonal-for-SCT-threaded-Scope-1_8816c6a4-d15b-4d84-afc9-ba6a23f3ec08.jpg?v=1788457875"},{"product_id":"william-optics-d-ep90-125-rc61","title":"William Optics 1.25\" 90° Erect Prism for Cat 61 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides a fully corrected, erect image for terrestrial viewing\u003c\/li\u003e\n\u003cli\u003eComfortable 90° viewing angle\u003c\/li\u003e\n\u003cli\u003eStandard 1.25\" barrel accepts most astronomical eyepieces\u003c\/li\u003e\n\u003cli\u003eDesigned specifically for the William Optics Cat 61 WIFD telescope\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003e1.25\" 90° Erect Prism for Cat 61 WIFD\u003c\/h2\u003e\n\u003cp\u003eThis 90° erecting prism converts the William Optics Cat 61 WIFD from an astronomical instrument into a high-magnification terrestrial spotting scope. It delivers a fully upright and non-reversed image through its standard 1.25\" barrel, making the Cat 61's apochromatic optics ideal for birdwatching, landscape observation, or any daytime viewing application.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eThe 90° Angle: Comfortable Daytime Viewing with the Cat 61 WIFD\u003c\/h3\u003e\n\u003cp\u003eWhile straight-through viewing is common in spotting scopes, the 90° angle of this prism provides a more comfortable and ergonomic viewing position, especially when observing targets at a high elevation or for extended periods. This design allows you to use your Cat 61 WIFD on a standard photo tripod without needing to crouch into an awkward position, mirroring the comfort of astronomical observation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e1.25\" Barrel: Universal Fit for Standard Eyepieces\u003c\/h3\u003e\n\u003cp\u003eThe prism features a standard 1.25\" barrel, ensuring compatibility with the vast majority of astronomical eyepieces. This allows you to leverage your existing eyepiece collection to achieve a wide range of magnifications for terrestrial viewing. You can use a low-power eyepiece for wide scenic views and switch to a high-power one to resolve fine details on distant subjects, all while maintaining a correctly oriented image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eErecting Prism vs. Mirror Diagonal: The Right Tool for the View\u003c\/h3\u003e\n\u003cp\u003eIt's important to select the right diagonal for your purpose. While this erecting prism is the definitive choice for daytime terrestrial use, a traditional mirror star diagonal is generally preferred for critical astronomical observing.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eErecting Prism (This Product):\u003c\/strong\u003e Uses a prism to correct the image both vertically and horizontally. This is essential for terrestrial viewing where an upside-down or mirrored view would be disorienting. The extra glass path can introduce minor chromatic aberration at very high powers on bright astronomical targets.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMirror Star Diagonal:\u003c\/strong\u003e Uses a highly reflective mirror to bend the light path. It corrects the image vertically but leaves it reversed left-to-right. This is perfectly acceptable for astronomy but unsuitable for terrestrial use. Mirror diagonals typically offer slightly higher light transmission and optical purity for faint deep-sky objects.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does the 1.25\" 90° Erect Prism do for my Cat 61 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt converts your Cat 61 WIFD telescope, which naturally produces an inverted and reversed image, into a terrestrial spotting scope. The prism corrects the image to be \u003cstrong\u003efully upright and correctly oriented left-to-right\u003c\/strong\u003e, making it perfect for daytime activities like birdwatching, nature observation, or surveillance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs this prism better than the standard star diagonal for astronomy with the Cat 61?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, for critical astronomical viewing, a high-quality mirror star diagonal is typically recommended. Erecting prisms involve more complex light paths that can introduce very subtle optical aberrations, which might be noticeable at high magnification on planets or double stars. This prism is specifically optimized for daytime terrestrial use where a correct image is mandatory.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the 1.25\" 90° Erect Prism to watch birds in a nearby park with my Cat 61?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. This is the ideal application for this accessory. Pairing the Cat 61 WIFD's excellent apochromatic optics with this erecting prism will provide sharp, color-correct, and high-magnification views of wildlife, far surpassing what is possible with typical binoculars or small spotting scopes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill I be able to see the Moon correctly oriented with this Cat 61 prism?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. While a mirror diagonal is often preferred for detailed lunar study, this erecting prism will show you the Moon exactly as it appears to the naked eye or on a map (upright and not mirrored). This can be helpful for identifying specific craters and features from a lunar atlas without having to mentally flip the image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I install the 1.25\" 90° Erect Prism on my Cat 61 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eInstallation is simple. You insert the 1.25\" nosepiece of the erecting prism directly into the 1.25\" eyepiece holder or visual back of your Cat 61 WIFD's focuser and secure it with the thumbscrews. Then, you can insert any standard 1.25\" eyepiece into the prism's eyepiece holder.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 1.25\" Erect Prism work with other telescopes besides the William Optics Cat 61 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile designed for the Cat 61 WIFD, this prism should work with most refractor telescopes that use a standard 1.25\" focuser or visual back. However, you must ensure your telescope has enough focuser travel to reach focus, as erecting prisms can sometimes require more \"in-focus\" or \"out-focus\" than standard diagonals.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":52853691711773,"sku":"WO-D-EP90-125-RC61","price":219.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WilliamOptics-1-25-90-Erect-Prism-for-Cat-61-WIFD-1_b2794600-6003-4a33-9db5-871534fa1d2d.jpg?v=1788457886"}],"url":"https:\/\/davidastro.com\/collections\/william-optics-visual-accessories.oembed","provider":"David Astro","version":"1.0","type":"link"}