A design of eyepiece, similar to a Kellner or achromatic Ramsden but with a two-element field lens. Aberrations, particularly astigmatism, are less than with the Kellner, and it gives good eye relief. Plössls will give good performance even with telescopes having a focal ratio as short as f/4. The design was invented in 1860 by the Austrian optician (Georg) Simon Plössl (1794–1868).
Subjects: Astronomy and Astrophysics.