1FL: Focal Length 2E / G: # Lens Elements / # Groups 3AF: Apparent Field of View 4G: Parfocal Group, eyepieces with the same letter are approximately parfocal -- require little (if any) refocusing when used together. 5ER: Eye Relief 6Eyepiece Dimensions: see diagram
A: Height of barrel above reference surface
B: Height of 1¼" barrel
C: Height of 2" barrel
D: Diameter of black barrel
E: Depth of 1¼" barrel
F: Approx. location of field stop
(negative number is above reference surface)