Focusing screen unit for single lens reflex camera

摘要

In an automatic focusing screen unit transparent photoelectric transducing means at a central portion of the image receiving surface area of a glass plate are capable of generating an output signal commensurate with the sharpness of an image formed thereon by an objective lens of a camera. An electrical circuit for processing the output signal of the transducing means produces an output during sharp focus. In a preferred embodiment, this circuit is constructed in the form of an integrated circuit chip for incorporation in the unit together with indicating means responsive to the output signal of the circuit for indicating a sharp focus condition.