Title:
IMAGE PICKUP LENS SYSTEM FOR VIDEO CAMERA
Document Type and Number:
Japanese Patent JPH04158330
Kind Code:
A
Abstract:
PURPOSE:To obtain the low-pass effect suitable for practical use with a simple structure by switching phase lattice type low-pass filters with different characteristics for use in an optical system with a variable focal distance and no afocal portion. CONSTITUTION:For 'WIDE', only a main lens system 2 is used for photographing, and a low-pass filter 1 is used. For 'TELE', the filter 1 is retreated, the lens system 2 is moved forward, a rear conversion lens system 5 enters behind it together with a filter 4, the focal distance is changed, and the low-pass effect is obtained by the filter 4. The optical low-pass filters 1, 4 with different characteristics for two focal distances are selectivity used, thus the cutoff frequency can be set to the same value for two focal distances to match the characteristics of a CCD 3 and a color filter. The lens 5 and the filter 4 are mechanically integrated, the filter 1 is retreated by the movement of the lens 5, and the low-pass effect can be obtained with a simple structure.
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Inventors:
SAITO TADASHI
Application Number:
JP28562790A
Publication Date:
June 01, 1992
Filing Date:
October 22, 1990
Export Citation:
Assignee:
KONISHIROKU PHOTO IND
International Classes:
G02B27/46; H04N5/225; H04N5/238; (IPC1-7): G02B27/46; H04N5/225; H04N5/238
Attorney, Agent or Firm:
Fujishima Ijima (1 outside)
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