Title:
レンズ交換式カメラの測光装置
Document Type and Number:
Japanese Patent JP5763415
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide a photometric device for a lens-interchangeable camera in which photometric correction is made more accurate and the speed of a correcting process is made higher.SOLUTION: A photometric device for a lens-interchangeable camera comprises: a photometric sensor configured such that a field divided into a plurality of photometric areas is subjected to photometry and each photometric datum according to a quantity of light received in the photometric areas is output; a photometric optical system configured such that light transmitted through a photographic lens and imaged on a focusing plate is guided to the photometric sensor provided outside the optical axis of the photographic lens; a correcting arithmetic circuit configured to calculate a correction value according to an open F value and an exit pupil position that are specific to the photographic lens; and a photometric arithmetic circuit configured to calculate corrected photometric data from the photometric data and the correction value. A correction arithmetic expression for calculating the correction value is composed of a first correcting expression and a second correcting expression. Each correcting expression is the result of the product of the function portion of each distance and a coefficient portion. The coefficient portions are made different from one another according to the open F value specific to the photographic lens.
Inventors:
Masashi Murakami
Application Number:
JP2011114640A
Publication Date:
August 12, 2015
Filing Date:
May 23, 2011
Export Citation:
Assignee:
Sigma Co., Ltd.
International Classes:
G03B7/20; G03B7/28; H04N5/235
Domestic Patent References:
| JP1109331A | ||||
| JP2011039293A |
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