In our first look at the Canon EOS-1D Mark III back in April, we described the camera's autofocus as being blazingly fast at acquiring initial focus and quicker off the line in dim light than any camera we'd used before. But at times, it also had real troubles holding focus on static subjects as well as tracking moving subjects. Over the last three weeks, we've been shooting extensively with two full production EOS-1D Mark IIIs in an attempt to figure out whether the autofocus weaknesses (and strengths) of the preproduction body carry over to shipping units. Here is what we've learned.

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