This is the flash I purchased together with my Canon AV-1 camera. Actually they came as a kit, with a regular 50 lens and a zoom/macro lens.
The Canon Speedlight 133A ia an automatic electronic, direct contact flash designed especially for the Canon A-1, AE-1, AV-1 and AT-1 single-lens reflex cameras. It mounts directly in the camera’s accessory shoe where it couples directly to the camera without the need for a synchronization cord. It is intended primarily for the use with ASA 80, 100 and 400 film and with lenses having a speed of f/4 or faster. Lacking the usual, complicated calculator dial, the Speedlite 133A makes flash photography about as easy as it can be. The A-1 or AE-1 with FD lens on “A” and with ASA 80, 100 or 400 film, is switched to the flash mode automatically when the pilot lamp glows – no special setting necessary.
With the AV-1 or AT-1, setting the lens aperture ring to f/4 ia all that is required. On all these cameras, the shutter speed is set automatically to the flash synchronization speed of 1/60 sec. when the pilot lamp glows. Compact and lightweight, the 133A is great for super-simple automatic flash shooting with other cameras as well.