1981-05-22
1984-04-10
Griffin, Donald A.
G03B 1308
Patent
active
044418027
ABSTRACT:
An Albada finder device includes a field frame provided on an eyepiece lens so as to be capable of reflecting part of the light from an objective lens, and a reflecting surface provided on the objective lens to reflect the reflected light from the field frame to the eyepiece lens to indicate a bright frame within the finder view field. The reflecting surface includes a central area containing the optical axis and passing light therethrough, a boundary area surrounding the central area, and a marginal area surrounding the boundary area and having a reflection factor greater than that of the central area. The boundary area has a reflection factor continuously varying so as to be smaller toward the optical axis and is formed in an annular shape having a width substantially equal to the diameter, on the reflecting surface, of a reflected light beam passing from a point of the field frame to the circumference of the exit pupil of the finder.
REFERENCES:
patent: 3517582 (1970-06-01), Pituley
Griffin Donald A.
Nippon Kogaku K.K.
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