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View Full Version : 580EX II: Does it improve AF assist performance -- and especially with Canon EOS 20D?


Doug Kerr
July 24th, 2007, 06:52 AM
Often I will shoot candids at social dances, using my EOS 20D and a Canon Speedlite 550EX flash unit. Generally, the ambient illumination is low, and I rely on the AF assist feature of the 550EX to enable use of autofocus. Generally, I have the center AF point preselected.

Of course, even at best, the overall AF cycle with AF assist in operation is slow, and I am often frustrated in making the shot I want at "the moment".

I know that there have been various improvements in the AF assist facility of the 580EX flash unit, and supposedly even further improvements on the 580EX II. I have no idea whether these improvements have any impact on the matter of concern to me.

Has anyone had experience with upgrading from the 550EX to the 580EX II (especially on an EOS 20D) insofar as AF assist performance is concerned?

Thanks.

Steve Saunders
July 25th, 2007, 03:18 AM
I've actually turned off AF assist with the EXII on the MkIII. I'd seen that some other Canon DSLR's were inclined to hunt a bit in very low light compared to Nikons (seen this in some of the night-time press scrums), but the MKIII AF is well up to the job in very low light. I might turn the AF assist back on and do a bit of testing soon.

Doug Kerr
July 25th, 2007, 04:07 AM
Hi, Steve,

I've actually turned off AF assist with the EXII on the MkIII. I'd seen that some other Canon DSLR's were inclined to hunt a bit in very low light compared to Nikons (seen this in some of the night-time press scrums), but the MKIII AF is well up to the job in very low light. I might turn the AF assist back on and do a bit of testing soon.

I may even try the same approach with the 20D, even though certainly its low-light AF performance is not up to that of the 1D Mk III.

Thanks for your insight.

Best regards,

Doug

Ben Rubinstein
July 26th, 2007, 10:48 AM
I have it off most of the time, slows down the AF in everything but pretty dark situations. I'm shooting 5D's.