Patent ID: 6384984
Filing Date: 2002-05-07
Classification: G02B

Abstract:
Eyepiece variable focal length optics which comprises, in order from objective optics with which it is used in combination, a negative first lens group, a positive second lens group and a positive third lens group, the first and second lens groups moving in opposite directions along an optical axis during variable focal length but the third lens group being stationary, and the eyepiece variable focal length optics satisfying the following conditions (1) and (2):2.03/f2<4.0â€ƒâ€ƒ(1) 7.012/f(h)â€ƒâ€ƒ(2) where f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, f(h) is the shortest focal length of the overall eyepiece variable focal length optics, and L12 is the axial air gap between the first and second lens groups at the shortest focal length.