Patent ID: 6252729
Filing Date: 2001-06-26
Classification: G03B

Abstract:
A real image type finder optical system having an objective optical system and an eyepiece lens arranged so that their optical axes are parallel to each other, in which a light beam having an optical axis extending from said objective optical system to said eyepiece lens is bent at least two times in parallel with a prescribed plane, comprising:a first prism having a first face serving as an entrance surface for the light beam transmitted along the optical axis of said objective optical system, a second face for bending the light beam laterally and a third face inclined with respect to the first face in order to bend the light beam bent by the second face so that the optical axis of the light beam extends along a direction substantially perpendicular to the second face, the second face having a reflective coating;a second prism having a first face serving as an entrance surface for transmitting the light beam transmitted through said first prism, a second face having a slope opposed to a slope of the first face in order to obliquely bend the light beam towards an object side and toward the first face, and a third face serving as an exit surface for transmitting the light beam bent in order by the second face and by the first face; anda reflecting member having a reflective surface for bending the light beam transmitted through said second prism so that the optical axis of the light beam is substantially coaxial with the optical axis of said eyepiece lens,wherein a direction of the optical axis of the light beam transmitted through the third face of said second prism is substantially perpendicular to the direction of the optical axis of the light beam transmitted through the first face of said first prism; andwherein said reflecting member and said eyepiece lens are movable as a unit along the direction of the optical axis of the light beam transmitted through the third face of said second prism.