Speedlites equipped with A-TTL are fully compatible with all EOS cameras. TTL is identical to A-TTL in almost every way, except there is no preflash. It can be used in every camera exposure mode. In Program mode, TTL always selects an aperture value based on the level of available light. Therefore, even in bright daylight conditions, a fast lens can be used at a wide aperture to blur the background and emphasize the subject in portraiture, using the flash to provide shadow- fill.
FP flash is automatic and simple to use.
Be careful when using flash for shadow-fill in sunlight. Flash shadow-fill also creates flash shadows of its own. The Elan II drops flash exposure 1.5 stops below normal for shadow-fill. Only EX flashes can do this. The manual for your flash has a table of the guide numbers for all shutter speeds and focal lengths from 28 to 105 mm.