I'm new to Canon world. I want to buy a flash to my EOS5. The options are: 540EZ and 550EX. 540EZ has A-TTL, 550EX is more future-proof in terms of upgrading to, say, EOS1v (E-TTL is useless with EOS5). The question is, which is a better bet? Is A-TTL really useful? I heard that A-TTL is a fully automatic mode where you can't control aperture and depth-of-field? In this case, I don't really want it.

-- Peter Larin (peter.larin@ecr.ericsson.se), March 01, 2000

Answers

In Av, Tv and M modes, the 540EZ reverts to "simple" TTL; you control the aperture, shutter speed or both. Only in P mode (or any of the PIC modes) does it use A-TTL and controls both aperture and shutter speed. The 540EZ is definitely better suited for the EOS 5, but you must decide about possible future body upgrades.

-- Dave Herzstein (dherzstein@juno.com), March 01, 2000.

I just thought of another point in favor of 540EZ. By the time I upgrade to a newer body, Canon could be releasing a newer model in the EX line.

-- Peter Larin (peter.larin@ecr.ericsson.se), March 02, 2000.