Do you see the assist beam fire? The MKIII can not control the 580ex flash only the 580ex II. With the 580ex simply set it in the flash itself to use the assist beam. I do weddings with MK3 and 580ex 1 in seriously LOW light with great success.
I am not saying that you do not have an issue I have seen strange things....
Dec 13, 2008 at 05:24 PM
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