Flash Photography 
In addition to its standard flash sync system, the Mamiya 645 PRO TL features TTL (through the lens), off the film (OTF), electronic flash exposure automation. A flash sensor located inside the camera body reads the flash reflected from the film surface at the moment of exposure. The .sensw is connected via coilcords to a dedicated electronic Metz SCA 396 thyristor module, which is attached to the flash shoe of the camera. The module has an IS0 dial on which the speed of the film in use is set. The resulting flash exposure automation determines correct flash exposure and automatically adjusts the output of the flash. It also automatically corrects for exposure compensation ordinarily required when using filters, close- up bellows or extension tubes. However, as all TTL systems, it requires manual compensation for differences in film surface reflection characteristics. Compensation is made by adjusting the film speed selector setting an SCA 396 module. The amount of compensation is determined by experimentation.
Important:
Read Operating Instructions which are supplied with flash unit before use.
Always turn off camera’s power switch when attaching or removing flash units.