Baader Planetarium 24mm Hyperion Eyepiece for 1.25" Focusers Consisting of 8 elements in 5 groups (3.5 mm - 21 mm), the Hyperion optical design delivers outstanding sharpness and color correction over a 68-degree wide apparent field (65 degrees for the 21 mm) The Hyperion optical design has been chosen to deliver a exceptionally comfortable view, thanks to its 20 mm of eye-relief, large eyelens, and a pupil free of the kidney-beaning and blackouts common in many wide field eyepieces