Title:
RETRO-FOCUS TYPE LENS
Document Type and Number:
Japanese Patent JPH05215964
Kind Code:
A
Abstract:
PURPOSE:To shorten the overall length by composing the retro-focus type lens of a 1st negative meniscus lens which has a convex lens opposite the object plane and a 2nd biconvex lens in order from the object side, making at least one of the surfaces of the 1st and 2nd lenses aspherical, and providing an aperture stop in the 2nd lens. CONSTITUTION:The 1st lens 1 and 2nd lens 2 are arranged in order from the object side and a parallel plane plate 3 is arranged behind the 2nd lens 2. The 1st lens 1 is a negative meniscus lens which has its convex surface opposite its object plane. The 2nd lens 2 is a biconvex lens. At the outer periphery of the 2nd lens 2, a V-shaped groove 4 is provided as the aperture stop opposite the optical axis. At least one of the surfaces of the 1st and 2nd lenses 1 and 2 is made aspherical. Consequently, the lenses and aperture stop member are reduced, the overall lens length can be shortened, and the retro-focus type lens which is small in size and inexpensive is obtained.
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Inventors:
TAKEI SHOICHI
Application Number:
JP4762292A
Publication Date:
August 27, 1993
Filing Date:
February 04, 1992
Export Citation:
Assignee:
KIYOUSERA OPT KK
International Classes:
G02B13/04; G02B13/18; (IPC1-7): G02B13/04; G02B13/18
Attorney, Agent or Firm:
Hideki Yamamoto