Image pickup apparatus including selective insertion of ND filter into taking lens optical path based on luminance of object to be imaged

A method for compensating position of focal plane of an optical lens system used in an image pickup apparatus comprising steps of:

• sensing a luminance of an object;
• judging whether the luminance of the object is higher than a predetermined value or not;
• inserting a neutral density filter into an optical path of an optical lens system when the luminance of the object is higher than the predetermined value;
• and
• compensating position of focal plane of the optical lens system after inserting the neutral density filter into the optical path.

An image pickup apparatus comprising:

• an image pickup device;
• an optical lens system;
• a luminance sensor for sensing a luminance of an object;
• a judging device for judging whether the luminance of the object is higher than a predetermined value or not;
• a neutral density filter to be inserted into an optical path of the optical lens system;
• a driver for inserting the neutral density filter into the optical path when the luminance of the object is higher than the predetermined value;
• a first compensator for compensating output signals from the image pickup device after insertion of the neutral density filter;
• and
• a second compensator for compensating position of a focal plane of the optical lens system after insertion of the neutral density filter.