With a wide angle of view and generous eye relief, the Alpine Astronomical Baader Hyperion 68° 17mm Astronomical Eyepiece delivers the performance that avid amateur astronomers demand for viewing and imaging. Engineered with an 8-element/5-group lens design, the eyepiece features Baader's proprietary 7-layer broadband multi-coatings to maximize light transmission across the entire visual spectrum with true color rendition and without the green tint and halos common in many astronomical eyepieces.
Baader made this eyepiece with a unique modular design that allows it to fit into standard 1.25" holders and accessories with the ability to remove the primary snout and have it fit into larger 2" holders. Since one of the lens groups is in the 1.25" snout, when it is removed it changes the focal length without changing the brightness or long 20mm eye relief. The focal length can also be changed through the use of compatible filters—allowing you to customize the magnification yield based on your optical tube assembly and need.
The eyepiece comes with a fold-down rubber eyecup for use with or without eyewear, and the eyecup can be completely removed to reveal a set of two threads. These M43 and M54 threads allow T-rings and other adapters to be mounted for direct connection of imaging systems for afocal and projection astrophotography techniques. This model is parfocal with all other Hyperion eyepieces except the 24mm version, which means there is little to no need to refocus when changing eyepieces within the Hyperion line.