Jeff
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 p.8 #7 · ['NEW Fix' UPDATE!] - MkIII AF still broken | |
I personally think that it is some physical characteristic of the AF assembly design that has gone awry. I spent some time yesterday looking through some MkIII images, and confirmed that I actually am seeing something that I only 'thought' I might be seeing previously. I wish I had the image here at work to post as an example, but will have to wait until tonight.
I've seen a few people mention AF plane vs. sensor field issues that result in a lateral inconsistency in the field of focus, not quite like the results of a view camera, but something similar. In my case, the image in question that illustrates it best is of a series of ridgelines, each of which is close enough to parallel to the sensor to be considered roughly equidistant (DOF-wise). The ridge is admittedly further away on the left side than the right, but it is >1 mile away (shot with a 70-200/2.8L IS at f/2.8), so I really doubt that the left side could be out of the plane of the DOF while the right side remains within it. The effect that I see in the image is that as you follow the primary ridgeline from right to left (landscape orientation), it becomes more and more out of focus until at the left edge it looks absolutely horrible. It's almost impossible to see with the image 'fit on screen', somewhat hard to see at 50%, but glaringly obvious at 1:1. The image in question printed at anything beyond about 5x7 would look marginal, at best.
There's no way to know whether it's a sensor alignment issue, or a lens mount issue, or related to the dust shaker, or...  I can't fathom how it could be a user error phenomenon, though perhaps after the 'sheep incident' someone can point out the error in my ways.  Since the variability is horizontal in orientation, I also can't see how it could be related to focus mechanism movement during exposure, as some have postulated for the 'ghosting' issue. I've noted that some 1D MkIII users have reported some images to almost have a very, [very extremely limited depth of field, and what I'm seeing is along those lines.
I'll try to post the image with 100% crops tonight so you all can see what I'm talking about. I've thought that I've seen this before in some of my images, but I never thought much of it, since I never tried to print any of the images. The main thing about this issue is that if it's widespread, it likely affects all types of shooters, not just sports guys shooting fast-paced people sports. Hopefully it's just an issue with mine.
The question in my mind is now this: is this effect related to the secondary image (i.e. 'ghosting') issue? Jeez, I hope that it's related, because if my camera needs a third trip to Canon to make it right, that'll be when I call it enough. 'Lemon Law' or class action lawsuit, if this thing ain't fixed within a year of it's release, something will need to be done, despite how good the camera otherwise is.
[As an aside, my 60" Sony XBR1 SXRD rear-projection TV has a class action settlement going on right now, and it's for a heck of a lot less than this issue with the MkIII. I will likely end up with a brand-new XBR2 (after two strikes of repair attempts) two years after buying it for $4000, so no one should try to say that it can't happen to Canon, too. Oddly, it was a first generation product that, other than the inherent defect in the optical block, gives the finest 1080p HD image out there, bar none. IMHO.  ]
Cheers...
-Jeff
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