QUOTE (michael @ Aug 3 2008, 05:42 AM)
It's important to note that only photographers who are shooting subjects in rapid motion at larger apertures who are going to encounter focus issues with the new Canon One series cameras. The other 95% will likely never see it.
But, having said that, it's a big black eye for Canon.
Michael
Michael, unfortunately the issue isn't confined to subjects in rapid motion according to Galbraith, viz:
"Every word about the EOS-1D Mark III and firmware v1.1.3 applies equally to the EOS-1Ds Mark III with firmware v1.0.6 installed. It shares the same tendency to imagine or overestimate forward motion and the same difficulty holding focus on a stationary subject. "
"With either the EOS-1D Mark III and firmware v1.1.3 or the EOS-1Ds Mark III with firmware v1.0.6, AI Servo autofocus won't hold still on a static subject. "
"Just enough testing was done to reveal a few things. Whereas the older firmware can introduce a change in focus distance with each One Shot activation, even if the AF point is aimed at the same subject at the same distance each time, the newer firmware seems to give more repeatable and accurate focus results under the same conditions. But if the test is done slightly differently - setting the focus to some other distance, then focusing one time on the subject using One Shot, autofocus variability seems about the same as before: there's too much."
"To give yourself a reasonable chance with One Shot, it looks like you'll want to pump the autofocus two or three times with it pointed at the same area of the subject. Alternatively, switch the camera to AI Servo, configure it to autofocus only when the rear AF-ON button is pressed, then "lock" the focus by releasing AF-ON. Not only did AI Servo produce more consistent stationary subject autofocus than One Shot (albeit in limited testing), it also means you don't have to switch AF settings when the subject starts to move. Just press AF-ON.
I Servo autofocus won't hold still on a static subject. "
"Static focus stability - which was a real source of telephoto shooting troubles with the EOS-1Ds Mark III through the early months of 2008 here - is much improved, though some twitchiness remains."
"When these cameras are set to AI Servo, the newest firmware is loaded and the subject being photographed is stationary or moving slowly, the results are much better than before: autofocus is now acceptably stable and acceptably accurate. The cameras' tendency to shift the focus is still lurking inside, it's just mostly dormant."
These quotes would seem to indicate that the focus issue is more general, but the firmware up-grades help (less than 100%) with both cameras.
Where you say the other 95% will likely never see it - maybe so. The problem here is the real difficulty of sorting out cause and effect when there is also an anti-aliasing filter in the path softening the image regardless of how well focused it is. So what we really need to do when we pixel-peep raw files for focus is adjust for background anti-aliasing. This means we are looking at second-order differences of sharpness between a correct and a slightly incorrect focus. Perhaps not easy except under well-controlled conditions designed to parse this dual causality.
Cheers,
Mark
Edited 10:10 PM EDT to unscramble two quotes.