Wide-angle lens

Details Wide-angle lens Wide-angle lens

1994-07-15

1997-05-20

Epps, Georgia Y.

Optical: systems and elements

Lens

Reverse telephoto

359708, 359770, G02B 1304

Patent

active

056317808

ABSTRACT:
A retrofocus type wide-angle lens for achieving a highly stable imaging performance and a reduction in spherical aberrations, astigmatism, and coma, while allowing for a large aperture and a large wide angle of view. The retrofocus type wide-angle lens has, in the following order from an object side, a first lens group having a negative refracting power and being fixed in a focusing operation and a second lens group having a positive refracting power and being moved in the focusing operation. The first lens group has, in the following order from the object side, a first unit with a negative refracting power and a second unit having a positive refracting power. The second lens group has, in the following order from the object side, a first unit with a negative refracting power, a second unit with a positive refracting power, a third unit with a negative refracting power and a fourth unit with a positive refracting power. The third unit of the second lens group having a cemented lens formed of a lens with a negative refracting power and a lens with a positive refracting power, the cemented lens constituting a negative meniscus lens with a convex surface directed to an image side.

REFERENCES:
patent: 4029397 (1977-06-01), Yamashita
patent: 4776680 (1988-10-01), Tanaka
patent: 4806003 (1989-02-01), Mukai et al.
patent: 5325236 (1994-06-01), Tanaka

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