A single lens reflex camera or a camera system uses a camera body unit and has a view finder unit permanently fixed to or detachably mounted on the camera body. A first terminal on the camera body is electrically connected with a synchronous device which is so arranged as to provide a synchronous signal related to the operation of a shutter device, while a second terminal which can contact with or can be coupled to the first terminal on said camera body when the view finder unit is attached to the camera body unit, is provided on the view finder unit. Therefore one or more electrical devices, which are built in the view finder unit or are detachably mounted on the view finder unit and require the synchronous signal related to the operation of the shutter device for having themselves activated, are electrically connected to the synchronous means through the contacting or coupling of the second terminal with the first terminal. A latch holds the view finder in position and aligns it with the camera body.