Originally Posted by tuthill
What about future compatability with whatever Canon d-slr I get next? I've heard it's not an issue with the 550EX, but some feel it may be with the 500DG Super? I've currently got the 420EX but may sell it for a 500 Super as I wouldn't mind the higher guide number (distant swimmers at meets). gary
Well if you're with Canon for a long time like I'm then you certainly remember that 1st their E and then their EZ (or EG) flashes are not really upward compatible with their EX series!
Also the new E-TTL II is really about distance encoding with the lenses like on similar systems from Minolta/Nikon, and not part of any improvement in the flash head. It seems to me like the older Canon lenses are more of an issue here: http://photonotes.org/articles/eos-f...ex.html#ettlii
Beside the EF-500DG Super provides full manual control, and an indepedent photoeye so you can always use this unit on manual or even with studio strobes. It looks to me like you are more stuck
with the 420EX! http://www.photo.net/bboard/q-and-a-...?msg_id=006KAs