Patent ID: 6867916

Claim:
A viewfinder optical system comprising: a lens system having at least one lens; a first prism on which the light from said lens system is incident, wherein said first prism comprises (a) a curved incident surface on which the light from said lens system is incident and (b) a curved reflection surface with a positive optical power; a second prism on which the light from said first prism is incident; and an eyepiece lens on which the light from said second prism is incident, wherein a primary image is formed between said first prism and said second prism, wherein said lens system and said first prism provide an exit telecentric system, with exit telecentricity not being established prior to the reflection by said curved reflection surface, wherein said viewfinder optical system satisfies the following condition, 21°≦θ≦24° where θ is the angle of incidence, with respect to said curved reflection surface, of a light ray that entered said first prism along an optical axis of said viewfinder optical system, and wherein said curved reflection surface is a rotationally asymmetric surface.