{"product_id":"svbony-sv135-7-21mm-52-36-zoom-eyepiece-125in","title":"SVBONY SV135 7-21mm 52-36° Zoom Eyepiece - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e7mm to 21mm zoom focal length\u003c\/li\u003e\n\u003cli\u003e60° (at 21mm) to 40° (at 7mm) apparent field of view\u003c\/li\u003e\n\u003cli\u003eStandard 1.25\" barrel size\u003c\/li\u003e\n\u003cli\u003e13mm - 15mm of eye relief\u003c\/li\u003e\n\u003cli\u003eFully multi-coated optics for high 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\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 SV135 1.25\" 7-21mm Zoom Eyepiece\u003c\/h2\u003e\n\u003cp\u003eThe Svbony SV135 1.25\" 7-21mm Zoom Eyepiece replaces a whole set of fixed eyepieces, offering a continuous focal length range from 7mm to 21mm with a simple twist. Its 7-element, 4-group optical design is fully multi-coated, delivering a 60° field of view at its widest setting. With 13mm to 15mm of eye relief and a weight of just 145g, it provides a versatile and comfortable viewing experience for planetary and lunar 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\u003eThe 7-21mm Zoom Range: Instant Magnification Adjustment\u003c\/h3\u003e\n\u003cp\u003eThe core advantage of the SV135 is its ability to change magnification without swapping eyepieces. You can start at the 21mm setting for a wide, low-power view to easily locate an object like Saturn, then simply twist the barrel to zoom in to 7mm for a high-power, detailed view of the rings—all without ever taking your eye from the telescope or losing the object from the field.\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\u003e60°-40° Field of View and Fully Multi-Coated Optics\u003c\/h3\u003e\n\u003cp\u003eThe SV135's 7-element optical system is fully multi-coated to maximize light transmission and contrast, which is critical for discerning faint details on Jupiter's cloud bands or resolving stars in tight clusters. The apparent field of view varies with magnification, from a wide 60° at 21mm to a more focused 40° at 7mm. This is a necessary trade-off in a zoom design, prioritizing magnification power at the high end.\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\u003eErgonomics for Viewing: 15mm Eye Relief and 1.25\" Filter Threads\u003c\/h3\u003e\n\u003cp\u003eWith an eye relief range of 13mm to 15mm, the SV135 is comfortable for most observers, including those who wear glasses. A twist-up rubber eye guard helps block stray light and maintain proper eye positioning. The standard 1.25\" barrel is compatible with virtually any telescope, and the M28.5*0.6 threads allow you to attach standard 1.25\" filters, like a moon filter for reducing glare.\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\u003eSV135 Zoom vs. Fixed Focal Length Eyepieces: The Convenience Trade-Off\u003c\/h3\u003e\n\u003cp\u003eWhile a set of individual Plössl eyepieces might offer a wider, flatter field at each specific focal length, the SV135 zoom offers unparalleled convenience. It is an ideal solution for public outreach, travel scopes, or for observers who want to quickly find the optimal magnification for changing atmospheric conditions without carrying a case full of accessories.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eAdvantage of the SV135:\u003c\/strong\u003e One eyepiece covers a wide range of magnifications, is cost-effective, and simplifies your observing kit.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAdvantage of Fixed Eyepieces:\u003c\/strong\u003e Typically provide a wider apparent field of view and potentially sharper edge-of-field correction compared to a zoom at the same focal length.\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 is the main advantage of the Svbony SV135 zoom eyepiece?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary advantage of the \u003cstrong\u003eSvbony SV135\u003c\/strong\u003e is convenience. It allows you to change magnification from a low-power \u003cstrong\u003e21mm\u003c\/strong\u003e to a high-power \u003cstrong\u003e7mm\u003c\/strong\u003e with a simple twist, eliminating the need to swap between multiple fixed-focal-length eyepieces. This is ideal for tracking objects or finding the perfect magnification for current seeing conditions.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the field of view of the SV135 change when I zoom?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe apparent field of view (AFOV) on the \u003cstrong\u003eSV135\u003c\/strong\u003e is variable. It is at its widest, \u003cstrong\u003e60°\u003c\/strong\u003e, at the 21mm setting. As you increase magnification by twisting towards the 7mm setting, the field of view narrows to \u003cstrong\u003e40°\u003c\/strong\u003e. This is a common characteristic of zoom eyepiece designs.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 13-15mm eye relief on the SV135 comfortable for eyeglass wearers?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the \u003cstrong\u003e13mm - 15mm\u003c\/strong\u003e eye relief is generally sufficient for most eyeglass wearers to see the majority of the field of view comfortably. The adjustable rubber eye guard also helps in finding the optimal viewing distance from the lens.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would I use the SV135 zoom eyepiece to observe Jupiter with an 8\" f\/10 SCT?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWith an 8\" f\/10 SCT (2032mm focal length), you would start with the \u003cstrong\u003eSvbony SV135\u003c\/strong\u003e at the 21mm setting to get a wide, low-power view (97x magnification) to easily find and center Jupiter. Once centered, you can smoothly twist the eyepiece towards 7mm, increasing the magnification up to 290x to see details like the Great Red Spot and individual cloud bands, stopping at the point where the image is sharpest based on atmospheric conditions.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan the SV135 eyepiece show the entire Pleiades (M45) cluster in a small refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt depends on the refractor's focal length. The Pleiades (M45) is a very large cluster, requiring a wide true field of view. At its 21mm setting with a \u003cstrong\u003e60°\u003c\/strong\u003e apparent field, the \u003cstrong\u003eSV135\u003c\/strong\u003e may frame the cluster in a short focal length refractor (e.g., 400-500mm). However, in longer focal length telescopes, a fixed eyepiece with a wider field stop, like a 32mm Plössl, would be better suited for viewing the entire cluster at once.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use standard 1.25\" filters with the Svbony SV135?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The barrel of the \u003cstrong\u003eSvbony SV135\u003c\/strong\u003e is threaded with the standard \u003cstrong\u003eM28.5*0.6\u003c\/strong\u003e pitch, making it compatible with all standard 1.25\" astronomy filters, such as moon filters, color filters for planets, or light pollution filters.\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\u003eSKU\u003c\/td\u003e\n\u003ctd\u003eW9105D\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e7mm - 21mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApparent Field of View\u003c\/td\u003e\n\u003ctd\u003e60° - 40°\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\u003eEye Relief\u003c\/td\u003e\n\u003ctd\u003e13mm - 15mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Design\u003c\/td\u003e\n\u003ctd\u003e7 elements in 4 groups\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Coating\u003c\/td\u003e\n\u003ctd\u003eFully Multi-Coated Green\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eZoom Type\u003c\/td\u003e\n\u003ctd\u003eLinear\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Threads\u003c\/td\u003e\n\u003ctd\u003eM28.5*0.6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRubber Eye Guard\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eMetal + Optical Glass\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eColor\u003c\/td\u003e\n\u003ctd\u003eBlack\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet Weight\u003c\/td\u003e\n\u003ctd\u003e145g\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePackage Dimensions\u003c\/td\u003e\n\u003ctd\u003e110 x 80 x 70mm\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\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":52861231628573,"sku":"SV-W9105B","price":38.0,"currency_code":"CAD","in_stock":true}],"url":"https:\/\/davidastro.com\/products\/svbony-sv135-7-21mm-52-36-zoom-eyepiece-125in","provider":"David Astro","version":"1.0","type":"link"}