Rear focus conversion lens apparatus

Details Rear focus conversion lens apparatus Rear focus conversion lens apparatus

1984-07-18

1987-04-07

Corbin, John K.

350463, 350464, G02B 912, G02B 934, G02B 960, G02B 1502

Patent

active

046555587

ABSTRACT:
A rear conversion lens apparatus mounted between an objective lens and a camera body for enlarging the focal length of the composite system of the rear conversion lens apparatus and the objective lens more than the focal length of the objective lens includes a converter barrel removably mounted between the objective lens and the camera body, a lens group of negative refractive power movable along the optic axis within the converter barrel, the lens group of negative refractive power having a forward subgroup and a rearward subgroup, the forward subgroup having a negative meniscus lens disposed most adjacent to the object side and having its convex surface facing the object side and a positive lens disposed on the image side of the negative meniscus lens, and moving means for moving the lens group of negative refractive power along the optic axis. Focusing to objects at infinity to a short distance is effected by the movement of the negative lens group by the moving means.

REFERENCES:
patent: Re30708 (1981-08-01), Momiyama
patent: 4206971 (1980-06-01), Hamanishi et al.
patent: 4354743 (1982-10-01), Mihara
patent: 4392724 (1983-07-01), Hamanishi
patent: 4591234 (1986-05-01), Hamanishi

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