Title:
FOCUS DETECTING OPTICAL SYSTEM
Document Type and Number:
Japanese Patent JPH01224714
Kind Code:
A
Abstract:
PURPOSE:To obtain a focus detecting optical system which is superior in symmetry of an image and has a satisfactory and uniform image forming performance by constituting an image reforming lens, which forms a secondary image, of double convex positive lenses, each of which has at least one aspherical face, correspondingly to a divided pupil. CONSTITUTION:A condenser lens B having an aspherical shape is arranged at the rear of a primary image surface A formed by a photographic lens, and a stop C having a pair of aperture parts symmetrical with respect to a principal optical axis X0 is arranged in the position which is conjugate to the pupil of the photographic lens with respect to the condenser lens B or in the vicinity of this position. An image forming lens D where a pair of double convex positive lenses which are arranged symmetrically with respect to the principal optical axis X0 correspondingly to this pair of aperture parts and have aspherical faces are unified is arranged at the rear of the stop C. The condenser lens B is formed to an aspherical shape to stabilize the distribution of the quantity of light reaching a sensor on which the secondary image is formed. Thus, the focus detecting optical system of high performance is obtained which secures symmetry of the image and the satisfactory and uniform image forming performance and has a high reduction power function.
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Inventors:
MORIYAMA KEIJI
OKI YASUSHI
OKI YASUSHI
Application Number:
JP5131188A
Publication Date:
September 07, 1989
Filing Date:
March 04, 1988
Export Citation:
Assignee:
NIKON CORP
International Classes:
G03B13/36; G02B7/34; G02B13/18; (IPC1-7): G02B7/11; G02B13/18; G03B3/00
Attorney, Agent or Firm:
Takao Watanabe