Patent ID: 6038069
Filing Date: 2000-03-14
Classification: G02B

Abstract:
A real image type zoom finder comprising:(a) an objective lens including a plurality of lenses and having a positive refracting power;(b) a field diaphragm provided in a vicinity of a focal point of the objective lens, for defining a viewing field;(c) a structure for erecting an image formed by the objective lens; and(d) an eyepiece having a positive refracting power for enlarging an image formed by the objective lens and the field diaphragm,wherein said objective lens includes at least a first lens group provided closest to an object side, having a negative refracting power, and satisfies the following conditions:1.9<f.sub.B /f.sub.W and1.0<.vertline.f.sub.1 .vertline./f.sub.W <2.0where f.sub.B is a minimum value of a distance between a surface of the object lens closest to a pupil side and the field diaphragm, which is equivalent to a corresponding air distance, f.sub.1 is a focal length of said first lens group, and f.sub.W is a focal length at a wide angle end of said objective lens,wherein said objective lens comprises, from the object side:said first lens group consisting of a single lens;a second lens group having a positive refracting power;a third lens group having a negative refracting power; anda fourth lens group having a positive refracting power,wherein when magnification is varied between the wide angle end and a telephoto end, the second and third lens groups move along an axis of said objective lens while a distance on the axis between the second lens group and the third lens group is varied.