Quote Originally Posted by Chuck Lee


Mark, other than a few high end functions there's no difference between the two. I think the Guide #'s the same. The idea is that you get a more natural studio style look when the key is off to the side and higher than the subject. The on-camera flash will need to trigger the off camera flash and that is what the 580 is built to do. It does not mean that you can't turn the power down an use it for a on-axis fill.


Chuck, Canon has a sneaky way of embedding guide number into its product names. The 430 has a guide number of 43 (meters, at ISO 100 and f/1). The 580 has a guide number of 58 (meters, at ISO 100 and f/1). So, I guess the model number is the guide number in decimeters? (And the 580 adds full rotation head, external battery input, PC input, auto-thyristor flash, and the catchlight panel.)