Patent ID: 6154613
Filing Date: 2000-11-28
Classification: G03B

Abstract:
An optical apparatus having a diaphragm device including a diaphragm member which varies an aperture diameter for light measurement operation according to a focal length, comprising:a) zoom detection means for detecting a state of zooming and outputting information related to a present focal length of said optical apparatus;b) said diaphragm device including a stepping motor serving as a drive source to move said diaphragm member for varying the aperture diameter thereof; andan aperture diameter control circuit which determines an aperture diameter for said light measurement operation according to said information outputted from said zoom detection means and supplies an energization pattern corresponding to the determined aperture diameter to said stepping motor, said energization pattern being selected among plural energization patterns which differ by every aperture diameter, and said aperture diameter control circuit causes said diaphragm member to move so as to define said determined aperture diameter.