I took a bunch of shots the other day, focused on a window, trees in front but the line of sight between centre AF and window was clear yet the cam repeatedly focused on the tree, as if it was being influenced by data from the adjcent AF point.
Keep in mind your depth of field. If you're using a focus/recompose method, it's pretty easy to move the plane of the sensor around enough to throw the shot OOF. I also have the Mark III, and I do sometimes get weird OOF shots, but none look like yours. In my OOF shots, there is no discernible focus area at all -- Everything is soft and blurry. In your shots, it appears that the camera did focus on something... just not what you intended. Knowing how difficult it can be to work with narrow DOF conditions, I would urge you to test your combo out in more controlled conditions using a tripod and a static subject. Otherwise there are too many variables (and too much bad mojo about the Mark III) to solicit any kind of rational opinion from the shots you posted. Good luck, and I hope you get it all sorted.
-Rich
I tried this and it still looked like it was considering data from adjacent points, I only use On-Shot.
john660 wrote:
A VERY typical 1D III AF problem from my experience shooting wildlife with the various 1D Mk III bodies I have owned. In general, the camera works fantastically well in almost all situations for One-shot AF (as everyone knows, the Al Servo is a different issue altogether), but it has at least one serious flaw in it that causes front focusing and I'm pretty sure Canon still has no clue what's causing it. I find it occurs most in subjects that are black and white in a coloured setting, for instance, a badger in a sunny green field.
I have put in a long and detailed research request to Canon and Canon research development here in Calgary, Alberta and am waiting for their analysis of my shots and my findings.
There are two ways to try to mitigate the AF problems in these types of situations. One, just use center point AF (I rarely use surrounding assist points unless it's an action sequence) and two, if you suspect your camera is not focusing properly, focus and refocus continually and take shots the whole time. This helps ensure that you get one or two sharp shots out of the series. It's not ideal, but then again, neither is the 1D III as it currently is....Show more →
