FOCAL LENGTH CORRECTING DEVICE OF CAMERA

摘要

PURPOSE:To correct the position of a photographic optical system without raising the cost neither requiring a space by adding a detecting means which senses insertion/ removal of an optical element to a control means to correct the focal length in accordance with insertion/removal of the optical element. CONSTITUTION:A correcting device where an optical element 3 like a soft focus filter can be inserted to and removed from the photographic optical path of a photographic optical system 1 is provided with a detecting means 20 which senses insertion/removal of the optical element 3 and a control means 10 which controls the extent of correction of the position of the photographic optical system in accordance with the variance of the optical path length due to insertion/removal of the optical element 3. When the optical element 3 is inserted to the photographic optical path, the optical path length is extended and the control means 10 which senses this insertion corrects the position of the photographic optical system 1 in accordance with extension of the optical path length. When the inserted optical element 4 is removed, the control means 10 which senses this removal corrects the position of the photographic optical system 1 in accordance with relative reduction of the optical path length. A dummy filter is not required and the space and the cost for this filter are made unnecessary.