In a camera which permits the photographer to change one light measuring mode to another as desired according to the condition of the object to be photographed, when a shutter release action initiating operation and a light measuring mode change-over operation are concurrently performed, an inadequate exposure results from a certain length of time required for charging a storage capacitor if the camera is of the type which stores light measurement information through an analog storing process or for AD conversion if the camera is of the digital storing type; or an inadequate exposure results from a control action on the shutter if the camera is of the type requiring no process for storing the information such as a camera of the type measuring a light reflected by the film surface. This problem is solved by a safety device which inhibits a light measuring mode change-over action at least until completion of a process of storing light measurement information after a shutter release action is initiated in the case of the light measurement information storing type or inhibits the change-over action during a shutter control action if the camera is of the type which measures the light reflected by the film surface, etc. in a mode called the TTL direct metering mode without requiring any process of storing light measurement information.

A camera in which both a light measuring operation and an exposure data calculating operation are made operative in response to either a manual exposure operation of a shutter release member or a manual operation of a manually operable means to be operated for altering data stored in a storing means which is co-acting in the exposure data calculating operation.

A camera in which the automatic exposure control is conducted on the basis of measured light information obtained in accordance with the illumination of an object to be photographed. In the camera, a type of exposure control information that is predetermined irrespective of measured light information is supplied as first exposure control information into an exposure control circuit including an analog to digital converter. Subsequently, measured light information obtained through the operation of a shutter release of the camera is supplied thereinto as second exposure control information.

In the disclosed camera, an exposure value determining arrangement produces an electrical signal in response to a light measuring facility and a film sensitivity setting device. An exposure factor unit determines a combination of shutter speed and aperture value for a proper exposure in response to the exposure value determining arrangement. A control connected to the exposure factor unit varies the combination of exposure factors in the exposure factor unit in response to the set position of a program constant setting arrangement which is set for a particular program constant.

Most of the elements constituting this camera system consists of digital circuits, whereby a central processing unit is built in this camera system in such a manner that various kinds of photographic modes are possible without increasing the number of the elements.