{"product_id":"svbony-sv190-18mm-uf-ultra-flat-field-eyepiece-125in","title":"SVBONY SV190 18mm UF Ultra Flat Field Eyepiece - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e18mm Focal Length\u003c\/li\u003e\n\u003cli\u003e65° Ultra-Flat Apparent Field of View\u003c\/li\u003e\n\u003cli\u003e1.25\" Barrel Diameter\u003c\/li\u003e\n\u003cli\u003e20mm Long Eye Relief\u003c\/li\u003e\n\u003cli\u003e8-Element \/ 5-Group Optical Design\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\u003eSVBONY SV190 1.25\" UF18mm Ultra Flat Field Eyepiece\u003c\/h2\u003e\n\u003cp\u003eThe SVBONY SV190 UF18mm Eyepiece delivers a tack-sharp, flat 65-degree apparent field of view using a complex 8-element, 5-group optical formula. Its 18mm focal length provides versatile medium magnification ideal for deep-sky objects, while the generous 20mm of eye relief ensures comfortable viewing for all observers, including those who wear glasses. The 1.25-inch barrel is threaded for standard M28.5*0.6 filters, and its 23.4mm field diaphragm maximizes the corrected image area without vignetting.\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\u003eAn 8-Element, 5-Group Design for a Truly Flat 65° Field\u003c\/h3\u003e\n\u003cp\u003eUnlike simpler eyepiece designs that suffer from field curvature and astigmatism near the edges, the SV190 employs an 8-element, 5-group construction specifically to correct these aberrations. This means stars remain tight, round points from the center of the 65-degree field right to the edge stop. While more complex than a standard Plössl, this design is the key to its edge-to-edge sharpness, a critical factor for observers using fast telescopes prone to coma.\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 Eye Relief for Comfortable Viewing With or Without Glasses\u003c\/h3\u003e\n\u003cp\u003eWith a generous 20mm of eye relief, the SV190 allows you to position your eye at a comfortable distance from the lens and still see the entire field of view. This is a crucial feature for eyeglass wearers, who often cannot get close enough to eyepieces with short eye relief. The adjustable rubber eyecup also helps to block stray light and properly position your eye, enhancing contrast and comfort during long observing sessions.\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\u003eStandard 1.25\" Barrel with M42 T-Threads\u003c\/h3\u003e\n\u003cp\u003eThe SV190 fits any standard 1.25\" focuser or diagonal and features M28.5*0.6 threads for all your 1.25\" filters. A unique addition is the M42*0.75 T-thread concealed beneath the rubber eyecup. This allows for the direct, secure attachment of camera T-rings and other accessories, making the SV190 a capable eyepiece for afocal astrophotography projects where a rigid connection is essential.\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 makes the SVBONY SV190 18mm an 'Ultra Flat Field' eyepiece?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe SVBONY SV190 uses a complex \u003cstrong\u003e8-element, 5-group\u003c\/strong\u003e optical design. This corrects for field curvature, ensuring that stars remain sharp and point-like across the entire \u003cstrong\u003e65-degree field of view\u003c\/strong\u003e, unlike simpler designs which can show distortion at the edges.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the SV190 18mm perform on open clusters like the Pleiades (M45) in an 8-inch f\/5 Newtonian?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt's an excellent choice. The 18mm focal length provides a medium-power, wide view perfect for framing large clusters like M45. More importantly, its flat-field design will minimize coma and astigmatism at the edge of the field, which are common issues in fast f\/5 Newtonians, keeping all the stars in the cluster sharp.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 20mm eye relief on the SV190 eyepiece really enough for eyeglass wearers?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, \u003cstrong\u003e20mm of eye relief\u003c\/strong\u003e is considered very generous and is ideal for observers who wear glasses. You will be able to see the entire 65-degree field of view comfortably without having to press your glasses against the lens. It also includes a rubber eyecup for non-eyeglass wearers.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the SV190 18mm a good choice for planetary viewing of Jupiter or Saturn in a 102mm refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile its primary strength is wide, flat-field viewing of deep-sky objects, the 18mm focal length provides a useful medium magnification for planets. In a typical 102mm refractor (e.g., f\/7), it will yield around 40x magnification, which is great for locating the planet and seeing its moons. For detailed views of cloud bands on Jupiter, you would typically use a shorter focal length eyepiece for higher power.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the purpose of the M42*0.75 thread under the eyecup of the SV190 eyepiece?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis is a standard \u003cstrong\u003eT-thread (M42x0.75)\u003c\/strong\u003e. It allows you to securely attach accessories like a DSLR camera (with the appropriate T-ring) for afocal photography, where you take a picture through the eyepiece. It provides a much more stable connection than universal smartphone adapters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 65° field of view of the SV190 18mm compare to a standard Plössl eyepiece?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA standard 1.25\" Plössl eyepiece typically has an apparent field of view around 50-52 degrees. The \u003cstrong\u003e65-degree field\u003c\/strong\u003e of the SV190 provides a noticeably wider, more immersive window on the sky. This wider context is especially beneficial for observing large nebulae and star clusters.\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\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e18mm\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\u003eApparent Field of View\u003c\/td\u003e\n\u003ctd\u003e65°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEye Relief\u003c\/td\u003e\n\u003ctd\u003e20mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003e8 Elements in 5 Groups\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Coatings\u003c\/td\u003e\n\u003ctd\u003eFully Multi-Coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eField Stop Diameter\u003c\/td\u003e\n\u003ctd\u003e23.4mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Threads\u003c\/td\u003e\n\u003ctd\u003eM28.5 x 0.6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAccessory Threads\u003c\/td\u003e\n\u003ctd\u003eM42 x 0.75 (under eyecup)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEyecup Type\u003c\/td\u003e\n\u003ctd\u003eRubber\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\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\/svbony-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eSVBONY 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SVBONY","offers":[{"title":"Default Title","offer_id":52861232120093,"sku":"SV-W9149B","price":66.87,"currency_code":"USD","in_stock":true}],"url":"https:\/\/davidastro.com\/fr-us\/products\/svbony-sv190-18mm-uf-ultra-flat-field-eyepiece-125in","provider":"David Astro","version":"1.0","type":"link"}