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Title:
RETRO-FOCUS TYPE LARGE APERTURE LENS
Document Type and Number:
Japanese Patent JP3255490
Kind Code:
B2
Abstract:

PURPOSE: To provide a retro-focus type large aperture lens composed of six lenses and capable of improving various aberrations even with a F number of about 1.2 and a back focus longer than 1.1f by making a third lens a meniscus lens whose concave surface confronts the object side.
CONSTITUTION: A first lens L1 is a positive meniscus lens whose convex surface confronts the object side, a second lens L2 is a negative meniscus lens whose convex surface confronts the object side, a third lens L3 is a negative meniscus lens whose convex surface confronts the side of image forming surface, a fourth lens L4 is a negative meniscus lens whose convex surface confronts the object side, a fifth lens L5 is a biconvex lens whose surface of intensive curvature confronts the object side and a sixth lens L6 is a positive meniscus lens whose convex surface confronts the object side.


Inventors:
Nobuaki Toyama
Application Number:
JP13709893A
Publication Date:
February 12, 2002
Filing Date:
June 08, 1993
Export Citation:
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Assignee:
Fuji Photo Optical Co., Ltd.
International Classes:
G02B13/04; G02B9/62; (IPC1-7): G02B13/04
Domestic Patent References:
JP516021A
JP6488414A
JP2188710A
JP5710111A
Attorney, Agent or Firm:
Hiroshi Kawano