Plössl eyepieces are one of the most popular eyepieces among astronomy enthusiasts. They are inexpensive and have a relatively wide field of view (about 50 degrees). I received a Svbony SV131 eyepiece with a focal length of 32 mm and a mounting diameter of 1.25 inches for review. This is a four-lens eyepiece made according to the Plössl design.
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.
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 (f5…f6) when observing deep space objects (galaxies, nebulae, clusters). With “slow” telescopes (f8…f12), the eyepiece can be used for observing the Moon and bright compact objects in deep space.
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.
I received an SV152 20mm 70 Degree SWA Illuminated Eyepiece (SKU: W9115A) for testing. The manufacturer positions this eyepiece for the following applications: -setting the exact alignment of the telescope and finder -polar alignment (by drift method) –an invaluable aid to centering guide stars and astrophotography target objects -the perfect eyepiece for alignment of computerized GoTo systems
Field of view 70 degrees
Focal length 20 mm
Eye relief 16 мм
Crosshair – laser engraved
Lens group – 4 Group / 5PCS
Power – 2PCS 1.5V (AG5)
Lens Coated – FMC .
Field Stop – 25 mm
Thread – M28.5*0.6
Net Weight – 221g/ 7.8oz
Dimension – 75*53*102 mm