{"product_id":"svbony-sv135-7-21mm-60-40-zoom-eyepiece-125in","title":"SVBONY SV135 7-21mm 60-40° Zoom Eyepiece - 1.25\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e7mm to 21mm continuous zoom focal length\u003c\/li\u003e\n\u003cli\u003e57° to 40° variable apparent field of view\u003c\/li\u003e\n\u003cli\u003e18mm to 16.3mm of consistent eye relief\u003c\/li\u003e\n\u003cli\u003eFully multi-coated (FMC) 6-element optics\u003c\/li\u003e\n\u003cli\u003eStandard 1.25\" barrel with M28.5*0.6 filter threads\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\" Zoom Eyepiece replaces a case full of eyepieces with a single, versatile unit, offering a continuous focal length from 7mm to 21mm. Its 6-element, 4-group optical design delivers a variable apparent field of view from 57° down to 40°, while maintaining a generous eye relief of 18mm to 16.3mm for comfortable viewing. Weighing just 133g and threaded for standard M28.5*0.6 filters, this eyepiece provides seamless magnification changes for any telescope with a 1.25\" focuser.\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\u003e7-21mm Linear Zoom: Find, Center, and Magnify in One Motion\u003c\/h3\u003e\n\u003cp\u003eThe core of the SV135 is its linear zoom mechanism, which allows you to change magnification smoothly without swapping eyepieces. You can start at the 21mm setting for a wide, low-power view to easily locate and center a target like the Orion Nebula (M42). As you twist the barrel, you can seamlessly increase power up to the 7mm setting to resolve fine details, such as the individual stars of the Trapezium, all without ever taking your eye from the focuser.\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\u003eFully Multi-Coated Optics: A 57° to 40° Variable Field\u003c\/h3\u003e\n\u003cp\u003eThe SV135's 6-element optical system features fully multi-coated (FMC) surfaces to maximize light transmission and contrast. At its widest 21mm setting, the eyepiece presents a 57° apparent field of view, ideal for framing large star clusters. As you zoom to the 7mm setting for higher power, the field of view narrows to 40°—a necessary trade-off in zoom eyepiece design that provides the power needed for resolving planetary details or splitting tight double 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\u003eComfortable Viewing: 18mm Eye Relief and a 1.25\" Barrel\u003c\/h3\u003e\n\u003cp\u003eDesigned for accessibility, the SV135 maintains a long eye relief ranging from 18mm at 21mm to 16.3mm at 7mm. This consistency makes it an excellent choice for observers who wear glasses, eliminating the need to remove them to see the full field. The standard 1.25\" barrel ensures compatibility with virtually any telescope, and its lightweight 133g metal body won't create significant balance issues on smaller mounts.\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 Plössls: Convenience vs. Field of View\u003c\/h3\u003e\n\u003cp\u003eWhile a set of fixed focal length Plössl eyepieces will offer a consistently wider field of view (typically 50-52°), they cannot match the operational simplicity of the SV135 zoom. The ability to fine-tune magnification to perfectly frame an object or adapt to changing atmospheric seeing conditions is a significant advantage.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixed Eyepiece Advantage:\u003c\/strong\u003e Generally provides a wider, flatter field and potentially higher light transmission due to a simpler optical design.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSV135 Zoom Advantage:\u003c\/strong\u003e Unmatched convenience by eliminating eyepiece changes, making it ideal for outreach, travel scopes, or observers who prioritize a fluid viewing experience over a maximized field at high power.\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\"\u003eHow does the SVBONY SV135's field of view change as I zoom?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe apparent field of view on the SV135 is variable. It is at its widest, \u003cstrong\u003e57 degrees\u003c\/strong\u003e, at the 21mm focal length setting. As you increase magnification by zooming towards the \u003cstrong\u003e7mm\u003c\/strong\u003e setting, the field of view narrows to \u003cstrong\u003e40 degrees\u003c\/strong\u003e. This is a normal 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 18mm eye relief on the SV135 suitable for eyeglass wearers?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, absolutely. The eye relief ranges from \u003cstrong\u003e18mm to 16.3mm\u003c\/strong\u003e, which is considered long and provides ample distance for most eyeglass wearers to see the entire field of view comfortably without having to press their glasses against the lens.\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 zoom eyepiece?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The barrel of the SV135 eyepiece is threaded with the standard \u003cstrong\u003eM28.5*0.6\u003c\/strong\u003e thread pitch, making it compatible with all standard 1.25\" astronomy filters, such as moon filters, light pollution filters, or colored planetary filters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would I use the SVBONY SV135 to observe Jupiter with an 8\" Dobsonian?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe SV135 is perfect for this. You would start at the \u003cstrong\u003e21mm\u003c\/strong\u003e setting to easily find and center Jupiter in the wide 57° field. Once centered, you can smoothly zoom in towards the \u003cstrong\u003e7mm\u003c\/strong\u003e setting to increase magnification, allowing you to resolve details like the Great Red Spot and the main equatorial cloud bands without losing the planet from the field of view.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the SV135 a good choice for viewing the Moon in a small 70mm refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, it's an excellent choice for a \"grab-and-go\" lunar setup. At \u003cstrong\u003e21mm\u003c\/strong\u003e, you can frame the entire full Moon within the field of view. You can then zoom in to any focal length down to \u003cstrong\u003e7mm\u003c\/strong\u003e to get dramatic close-up views of specific features like the Apennine Mountains or the crater Copernicus, all with a simple twist of the eyepiece.\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 the SV135 zoom over a set of individual eyepieces?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary advantage is \u003cstrong\u003econvenience\u003c\/strong\u003e. Instead of carrying and switching between three or four separate eyepieces, the SV135 gives you every magnification between its 7mm and 21mm range in a single, 133g accessory. This allows for uninterrupted observing and the ability to perfectly match the magnification to your target and the current sky conditions.\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\u003e7mm - 21mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApparent Field of View\u003c\/td\u003e\n\u003ctd\u003e57° - 40°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEye Relief\u003c\/td\u003e\n\u003ctd\u003e18mm - 16.3mm\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\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003e6 elements in 4 groups\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eFully Multi-Coated (FMC)\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\u003eInterpupillary Distance\u003c\/td\u003e\n\u003ctd\u003e15mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eConstruction\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\u003eLength\u003c\/td\u003e\n\u003ctd\u003e93mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e133g \/ 4.67oz\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 Warranty Policy\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SVBONY","offers":[{"title":"Default Title","offer_id":52861231661341,"sku":"SV-W9105D","price":55.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/SVBONY-1-25inch-7mm-to-21mm-57-40-Zoom-Eyepiece-SVBONY-SV135-1-W9105D_6e076bb4-f50c-4a14-a8c1-2d9760f22f93.jpg?v=1788883298","url":"https:\/\/davidastro.com\/fr-us\/products\/svbony-sv135-7-21mm-60-40-zoom-eyepiece-125in","provider":"David Astro","version":"1.0","type":"link"}