a single frame is exposed when the shutter release is held down. Both units also have a second shutter release for vertical format shooting, and a subtractive frame counter. Only the AE Motor Drive FN has a motorized film rewind (therefore when using the AE Power Winder FN it is not necessary to remove the Rewind Coupler cover from the bottom of the camera). The AE Power Winder FN is powered by 4 AA batteries, and is a single self-contained, unexpandable unit. The AE Motor Drive FN is a more complete system, as it has 3 different battery packs to choose from: the Battery Pack FN, the Ni-Cd Pack FN, and the High Power Ni-Cd Pack FN. The Battery and High Power Ni-Cd packs will power the motor drive for up to 50 rolls of film, while the Ni-Cd pack provides power for up to 30 rolls. The Battery Pack FN takes 12 AA batteries. The two Ni-Cd packs have to be plugged into a charger to recharge them. The High Power Ni-Cd pack will also power the camera body itself by replacing the camera's battery with Battery Cord C-FN. Both units add the possibility of shutter-priority auto exposure mode by setting the lens's aperture ring to 'A'. The aperture needle disappears from the meter display, and the meter needle indicates what aperture the AE system has selected. Also, using either of the motor drive systems also enables use of electronic interval timers and remote shutter releases, both wired and wireless. Interchangeable backs The standard camera back is also interchangeable with a couple other units. One is the Data Back FN, which has 3 dials with letters, numbers, and Roman numerals. The left-hand dial is labeled "Year", and has a blank, 0-9, 82-93, I-X, and a-g; the middle dial is labeled "Month", and has a blank, 0-31, and A-G; the right-hand dial is labeled "Day", and has a blank, and 0-31. The back imprints the dial settings onto the film for classification or dating purposes, either at the time of shutter release, or when the manual record button is pressed. The Film Chamber FN-100 is a bulk film back which allows up to 100 exposures without reloading. It requires use of the AE Motor Drive FN. Special Editions In addition to the standard version of the New F-1, Canon produced a few special editions of the camera. Canon 50 years