I have a Canon Powershot Pro 70 camera with a 220 EX Speedlite. As far as I know, the PS Pro 70 isn't a E-TTL or A-TTL camera, and the 220 EX is a E-TT/TTL flash unit. So, the whole system should work as a regular TTL system. Still, the flash unit flashes 2 short pre-flashes before the main flash. Why's that? Why pre-flashes, thar are specific to E-TTL and A-TTL systems?

-- Dan Tancu (dtancu@yahoo.com), October 21, 1999

Answers

The "pre" flashes are for red-eye reduction. They are supposed to flash before the main flash, forcing the pupils of the subject to dialate (get smaller), thus reducing the red-eye. It doesn't completely remove it, only reduces it. You can turn this off in most camera's.

-- Dale R Dankulich (dalerd01@earthlink.net), October 21, 1999.