Focus detecting device with shielding

Details Focus detecting device with shielding Focus detecting device with shielding

1983-05-13

1984-11-20

Adams, Russell E.

354481, G03B 310

Patent

active

044836040

ABSTRACT:
A camera focus detecting device in which the first and the second images are respectively formed by a pair of secondary image forming lenses behind an expected focusing plane of a principal image forming lens. The focusing of the principal image forming lens is detected from position changes of the first and second images relative to a pair of photoelectric transducers on or near the focusing planes of the above pair of secondary image forming lenses so as to detect the position of the images. A first member, whose movement amount changes according to an F-number of the above principal image forming lens, and a second member, which moves in a certain determined direction when the first member moves to a certain determined position, are provided. With the movement of the second member the light shading amount of the light shading apparatus provided in front of the secondary image forming lens is changed to vary the above amount of light shading for the stepwise change of the F-number.

REFERENCES:
patent: 4253752 (1981-03-01), Ichihara
patent: 4322615 (1982-03-01), Fukuhara
patent: 4322616 (1982-03-01), Fukuhara et al.

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