The classic orthoscopic eyepiece has some advantages over popular Ploessl eyepieces of the same focal length, but especially compared to modern 'super-wide angle eyepieces':
- the low number of lens elements used results in very high light transmission with very high contrast and therefore gives an extremely clear, distortion-free image. The stars are perfectly sharp not only in the centre but also at the edge of the field of view.
- multi-coating ensures low internal reflections - separating the closest double stars with these eyepieces is a breeze, and the fine detail on planets emerges clearly.
- the orthoscopic eyepieces in this series are parfocal, i.e. almost no refocusing is needed when switching eyepieces.
Construction of an orthoscopic eyepiece: The optics consist of a plano-convex lens with a triplet, meaning there are only four air/glass surfaces. The interior is comprehensively blackened and effectively suppresses any stray light. In addition, the hard anodized barrel comes with an internal thread for taking filters.
