Omegon Super Plössl Zoom 7-21mm APO 30° - 43° 1.25" Eyepiece
The Omegon SP Zoom Series eyepiece offers a practical all-in-one solution for observers who want to cover a wide range of magnifications without switching eyepieces at the focuser. A single twist of the zoom ring takes you continuously from a comfortable 21mm wide-field view down to a tight 7mm high-magnification view - keeping the object in the field of view throughout, which is especially useful when examining a planet or the lunar surface and looking for the ideal magnification for the seeing conditions of the evening.
Optical design and image quality
The SP Zoom Series is built to the standards expected by modern telescopes. The optical system consists of five elements and delivers excellent contrast with minimal internal reflections. The APO designation indicates that the design has been optimised to suppress chromatic aberration - the colour fringing that can affect lesser zoom eyepieces, particularly at shorter focal lengths. Distortion is also well controlled across the entire zoom range, so stars at the edge of the field remain point-like rather than streaked. The apparent field of view of 43° is consistent throughout the zoom range, which means the image character does not change as you adjust magnification.
Comfort and practical features
Stray light is a common problem with zoom eyepieces due to the larger number of internal air-to-glass surfaces. Omegon addresses this with a rubber eyecup that shields the eye from ambient light and keeps the eye properly positioned at the exit pupil. This makes extended observation sessions noticeably more comfortable, particularly when working under partially lit skies or near street lights.
The eyepiece barrel features a machined safety notch - a small groove that engages with the thumbscrew of the focuser drawtube. This prevents the eyepiece from accidentally sliding out of the focuser when the telescope is pointed at high angles, such as when observing objects near the zenith. It is a small detail that matters in practice, especially with heavier zoom eyepieces.
Who is this eyepiece for
The Omegon Super Plössl Zoom 7-21mm is a versatile zoom eyepiece suited to beginners and intermediate observers alike. For someone setting up their first telescope, it removes the need to invest immediately in a full set of individual eyepieces - this single accessory covers the most commonly used magnification range. For more experienced observers, it serves as a convenient tool for initial object location and focusing before switching to a dedicated high-performance eyepiece for detailed study.
On a 700mm focal length telescope, the zoom range translates to magnifications between 33x at 21mm and 100x at 7mm - covering everything from wide star field views to detailed lunar crater inspection in one eyepiece. On longer focal length instruments the upper end extends further, making it practical for planetary work as well.
Compatibility
The 1.25" barrel fits the standard focuser size found on the vast majority of telescopes currently available. Refractors, reflectors and catadioptric telescopes with a 1.25" drawtube all accept this eyepiece without any additional adapter. The zoom ring turns smoothly and holds its position without creep, so the chosen magnification stays locked while you observe.
If you are looking for a single eyepiece that handles lunar observation, planetary viewing and general deep-sky exploration without constant swapping, the Omegon SP Zoom 7-21mm is a practical and well-built choice at an accessible price point.
