PURPOSE: To make it possible to shorten the arrangement position of the photodetector element and other circuit, by not only providing a print circuit substrate along the roof-shaped surface of a pentagonal roof prism, but also fixing a circuit adjusting element to this substrate.

CONSTITUTION: A discrete element is installed to the flexible print substrate 1 which forms an electric conductor 2, and it is provided along the roof-shaped surface of a pentagonal roof prism 9. On the other hand, since a photodetector element 10 is closely stuck and provided on the back face of the prism 9, an unstable phenomenon of the circuit does not occur and exact operation can be executed even if a high impedance circuit has been formed. Furthermore, since the adjusting resistors 4,4',4'', etc. are closely installed to the substrate 1, and the terminals of various switches 8 can be provided on the substrate 1, thickness of the circuit structure can be made extremely small, and the capacity in the camera can be utilized effectively.