PURPOSE: To obtain a titled adaptor having a good operability by automatically executing a fine adjustment of a position of a conversion lens, and matching its focus, in a roughly matched state of the focus by a manual operation, of a focus adjusting member of an interchangeable lens.

CONSTITUTION: When a focus is roughly adjusted by pointing a camera at an object to be photographed, and manually turning a range adjusting ring 5 of an interchangeable lens 3, an image of the object to be photographed moves in the optical axis direction in the vicinity of the photodetecting surface of an optical converting element 15. Its focus detecting state is detected by the optical converting element 15 and a focus detecting circuit 19, a moving lens barrel 10 is rotated by forward and backward rotations of a driving motor 22 through a focal adjustment controlling circuit 21, is moved in the optical axis direction, simultaneously a conversion lens also moves on the optical axis, and when the image position conforms with the photodetecting surface of the photoelectric transducer 15, the driving motor 22 is stopped through the focal adjustment controlling circuit 21 by a signal from the focus detecting circuit 19, the conversion lens 11 also stops moving, and the focal adjustment is completed.