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SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"
SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"

SVBONY SV135 7-21mm Zoom Eyepiece - 1.25"

by SVBONY
SKU SV-W9105A
CA$59.00 - CA$59.00
CA$59.00
CA$59.00 - CA$59.00
CA$59.00
Price Match Policy!
  • 7mm to 21mm linear zoom range
  • 57° (at 21mm) to 40° (at 7mm) apparent field of view
  • 1.25" barrel fits any standard focuser
  • 18mm to 16.3mm eye relief for viewing comfort
  • Threaded for standard M28.5*0.6 (1.25") filters
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • SVBONY SV135 1.25" 7-21mm Zoom Eyepiece

    The SVBONY SV135 zoom eyepiece replaces an entire set of eyepieces, offering a continuous focal length range from 7mm to 21mm in a single, 133g unit. Its linear zoom mechanism provides a wide 57° field at 21mm for locating objects, which smoothly narrows to a 40° field for high-magnification views at 7mm. With a comfortable 18mm to 16.3mm of eye relief and a standard 1.25" barrel, this eyepiece delivers instant magnification changes without swapping gear.

    One Eyepiece, Multiple Magnifications: The 7-21mm Zoom Range

    The core of the SV135's utility is its 7-21mm zoom range, which eliminates the need to carry and switch between multiple eyepieces. You can start at the 21mm setting to get a wide, low-power view for finding your target, then simply twist the barrel to zoom in to 7mm for detailed, high-power observation. This is ideal for tracking planets as they drift or for quickly framing different features on the Moon without losing your target.

    Fully Multi-Coated Optics: From a 57° View to 40°

    The SV135's 6-element, 4-group optical design features fully multi-coated (FMC) surfaces to maximize light transmission and contrast. At 21mm, you get an expansive 57° apparent field of view, perfect for sweeping star fields. As you increase magnification to 7mm, the field of view narrows to 40°, a necessary trade-off for the zoom mechanism that keeps the image sharp and focused through the range.

    18mm Eye Relief and a 1.25" Filter-Ready Barrel

    Designed for practical use, the SV135 provides a generous 18mm of eye relief at its lowest power, dipping only slightly to 16.3mm at 7mm, ensuring comfortable views even for observers wearing glasses. The standard 1.25" barrel is threaded with M28.5*0.6 threads, making it compatible with all standard 1.25" filters, like a moon filter or light pollution filter, to enhance your views.

    SVBONY SV135 vs. A Plössl Kit: Convenience vs. Field of View

    A zoom eyepiece is a direct alternative to owning several fixed focal length eyepieces. Compared to a standard kit of three Plössls (e.g., 20mm, 12mm, 7mm), the SV135 offers unmatched convenience. There's no fumbling in the dark, no risk of dropping an eyepiece, and no need to re-acquire your target after a swap.

    The primary trade-off is the apparent field of view. While the SV135 offers a wide 57° at 21mm, most fixed Plössls maintain a ~50° field across all focal lengths. The SV135's field narrows to 40° at 7mm, which is more constrained than a dedicated 7mm Plössl. For travel, outreach, or grab-and-go observing, the SV135's convenience is a clear winner; for critical observation where field of view is paramount, fixed eyepieces have an edge.

  • What is the main advantage of the SVBONY SV135 zoom eyepiece?

    The main advantage is convenience. The SVBONY SV135 combines multiple magnifications into one unit with its 7mm to 21mm zoom range. This allows you to find an object at low power and zoom in for a closer look without ever removing the eyepiece from the focuser.

    Does the field of view change when I zoom the SVBONY SV135?

    Yes, this is a key characteristic of most zoom eyepieces. The SVBONY SV135 has its widest apparent field of view, 57°, at the 21mm setting (lowest power). As you zoom in to the 7mm setting (highest power), the field of view narrows to 40°.

    How does the SVBONY SV135 perform on the Moon with an 80mm f/7 refractor?

    The SVBONY SV135 is an excellent choice for lunar observing with a small refractor. At 21mm, you'll see the entire lunar disk with context. You can then zoom in smoothly towards 7mm to get high-power views of specific craters, rilles, and mountain ranges along the terminator, all without changing eyepieces.

    Is the SVBONY SV135 a good choice for viewing Jupiter's moons in a 6" Dobsonian?

    Absolutely. In a typical 6" f/8 Dobsonian, the SVBONY SV135 provides a magnification range from about 57x to 171x. You can use the 21mm setting to easily frame Jupiter and all four Galilean moons, then zoom in to the 7mm or 10mm range to resolve cloud bands on the planet itself. The ability to adjust magnification on the fly is very helpful with non-driven mounts.

    Can I use filters with the SVBONY SV135 eyepiece?

    Yes. The 1.25" barrel of the SVBONY SV135 is threaded with standard M28.5*0.6 threads. This allows you to attach any standard 1.25" astronomy filter, such as a moon filter for reducing glare or a color filter for enhancing planetary detail.

    Is the image through the SVBONY SV135 as sharp as a fixed focal length eyepiece?

    While the SVBONY SV135 offers excellent views for its price, a high-quality fixed focal length eyepiece will typically have a slight edge in sharpness and a wider apparent field of view, especially at higher magnifications. The SV135 is designed to prioritize convenience and flexibility, making it a fantastic all-in-one accessory for many observing situations.

  • Focal Length 7mm - 21mm
    Barrel Size 1.25"
    Apparent Field of View 57° - 40°
    Eye Relief 18mm - 16.3mm
    Lens Design 6 Elements in 4 Groups
    Lens Coatings Fully Multi-Coated (FMC)
    Zoom Type Linear
    Filter Threads M28.5*0.6
    Eye Guard Yes, Rubber
    Interpupillary Distance 15mm
    Material Metal and Optical Glass
    Length 93mm
    Net Weight 133g / 4.67oz
    Color Black
  • SVBONY Warranty Policy