The zoom eyepiece is a variable focal length eyepiece that allows you to quickly change the magnification by simply rotating the special ring on the body. In fact, “zoom” can replace several eyepieces, and at the same time, you can easily find the optimal magnification for various objects. Zoom eyepieces are also very convenient for mass telescope observations (“sidewalk observations”), where changing the eyepiece takes a lot of time. A few years ago, I was able to observe the planets in a unique short-focus zoom eyepiece Nagler 3-6 mm – I really liked it for the convenience of choosing the best magnification, as well as its small size. About a year and a half ago, Svbony sent me the SVBONY SV171 Zoom Eyepiece 8mm-24mm for review, and after testing, I suggested that Svbony consider developing a planetary zoom eyepiece.

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Svbony company has kindly provided me with several eyepieces for testing. One of them – SV190 18mm 1.25″ Ultra Flat Field Eyepiece FMC. A flat field (no curvature), a large eye relief (20 mm) and a field of view of 65 degrees are declared. Interesting!

The focal length of 18 mm is one of my favorites, as it is especially in demand with “fast” telescopes (f\5…f\6) when observing deep space objects (galaxies, nebulae, clusters). With “slow” telescopes (f\8…f\12), the eyepiece can be used for observing the Moon and bright compact objects in deep space.

Svbony SV190 18mm 1.25

Svbony SV190 18mm 1.25″ Ultra Flat Field Eyepiece FMC

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I received an SVBONY SV171 Zoom Eyepiece 8mm-24mm (SKU: W9131A). for testing. The zoom eyepiece is very convenient for quickly selecting the optimal magnification, or for cases when you need to quickly change the magnification without having to change eyepieces. The focal length in the zoom eyepiece is changed by rotating the body. Along with the focal length, the angular field of view of the eyepiece also changes.

Declared characteristics:

Focal Length  8-24 mm
Eye Relief 18-19.5 mm
Apparent Field of View 38°-56°
Barrel Size 1.25″
Lens Structure  7-Elements/4-Groups
Filter Threads Standard 1.25″(M28.5 x 0.6)
Coatings Fully Multi-Coated
Blackened Lens Edges Yes
Barrel Safety Recess Yes
Eyecups Twist-Up, metal

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