Basically, a motorized version of the 503CX with addition of:
Acute Matte focusing screen
Universal 1/4 inch tripod socket
Battery compartment redesigned to fit 5 standard AA batteries, and battery level check feature.
TTL/OTF dedicated flash metering system; SCA 300 and SCA 500.
Working range of the sensor is ISO 16-1000.
Larger release button #46345 is supplied as standard, but the smaller release button #46116 can be used.
Use release cords FK30 and FK600 in front socket. Use release cord SK150 and connecting cord LK500 in side socket.
Built-in motor advances the film (up to 1.2 fps) and recocks the shutter after each exposure.
Operating Selector dial allows user to choose various pre-release options for mirror movement and shutter operation.
No shutter built in; uses C- and CF- lenses with built-in leaf shutters providing flash synchronization at all speeds.