| 摘要 |
PURPOSE:To control the position of an optical system correctly and accurately by providing an electric detecting means which is associated operatively with the quantity of movement of a photographic optical system capable of reciprocating in a movement area between the 1st ad the 2nd focal-length areas. CONSTITUTION:Five kinds of concentric patterns 63(63a-63e) for sliding are provided to a printed board 62 arranged above a cam plate which is associated with an AF device and the photographic optical system, and its periphery is divided into the wide-angle area W, movement area N, and telephoto area T of the optical system. Respective brushes are brought into contact with the respective patterns 63 to lead out the position signal of the optical system. A focal length selection member F is placed at a telephoto position T and a telephoto state is entered by placing a main optical system 3 at an extension position and a subordinate optical system 4 at an insertion position; and a wide-angle state is entered by setting the main optical system 3 at an contraction position and the subordinate optical system 4 at a standby position. Therefore, electric position detection is performed on the basis of the quantity of movement of the optical system and position control is carried out accurately and securely over the entire area by the simple constitution.
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