Glossary | Telescope accessories | Capacity | Type of build | Kellner
Kellner – the standard for many telescope sets
Kellner eyepieces consist of three lenses and have an apparent field of view of around 45 degrees. Since the lenses are cemented together, thereby creating an achromat, colour defects are hardly visible. Kellner eyepieces can be used for higher magnifications on telescopes with an aperture ratio of 1:10. The limit for Newtonian reflectors is an aperture ratio of 1:5, here you should instead use Plössl eyepieces.