Abstract: An apparatus for recording data to a film, executing: both unchangeable recording such as optical recording, and changeable recording such as magnetic recording for relatively important data, which is required protection from data failure and is permitted to change such as date, date print mode, and trimming direction of printing area, and executing: only magnetic recording for relatively unimportant data, which is allowed some data failure and has few possibility of changing such as aperture value, shutter time value, photometric value, exposure compensation value, and object distance value; wherein the apparatus is housed in a detachable back cover of a camera, and data being transmitted from the main body of the camera to the back cover.

Abstract: An apparatus for recording data to a film, executing: both unchangeable recording such as optical recording, and changeable recording such as magnetic recording for relatively important data, which is required protection from data failure and is permitted to change such as date, date print mode, and trimming direction of printing area, and executing: only magnetic recording for relatively unimportant data, which is allowed some data failure and has few possibility of changing such as aperture value, shutter time value, photometric value, exposure compensation value, and object distance value; wherein the apparatus is housed in a detachable back cover of a camera, and data being transmitted from the main body of the camera to the back cover.

Abstract: The focus detecting device comprises a primary imaging optical system, a focus detecting optical system, an aperture stop, deflection prisms and a photoelectrc transducing member which are arranged on an optical axis in the order from the object side. This focus detecting device is capable of having a wide focus detecting field angle, a high imaging magnification and a high focus detecting accuracy in addition to a short total length and favorable functions to correct aberrations.