Canon focus mystery

**Bruce in Philly** · 11-17-2010, 09:37 PM

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Why do I get perfect focus results on a 7D, and varied results a 5D MKII
and 50D requiring micro adjustment with the exact same lenses?
and two of
these three lenses do not focus properly and require micro adjustment. The 70-200 was dead spot on out of the box,
the 20mm was just a tad out but not really noticeable in pictures, and the
24-105 was so bad, it was just plain blurry.
I sent the 24-105 to Canon where they adjusted it somewhat but it still took
blurry pictures. Of course, the micro
adjustment in the camera makes everything perfect for these two errant
lenses. So, except for some worry about
Canon quality, I am very happy now with great focus performance on all three
lenses.
 OK,
so far so good, the issue appears to be the lenses with consistent results
across bodies. Unfortunately, he sent
the camera back because he was getting Error 80 seize ups but instead of
another 50D, he sprung for the 7D with a 28-135 kit lens.
 All four lenses focus dead accurate on his 7D
with no adjustments needed. The thing simply
focuses just plain spot on. Huh?!?
 We never
bothered to micro adjust on his 50D as so technically, I can’t say the results
were exactly the same, but, given our eyeballs, they were the same and the
24-105 was obviously incorrectly focusing on both cameras to a large
degree. We did not try his 28-135 on my
5D MKII. Looking back on it, I probably
should have exchanged the whole 5D and kit lens for such poor focus performance
but I didn’t as I could adjust it in camera (1 click less than the max). I decided to send it back after a few months
because it just bothered me. For focus testing, I used to use a print out
laid on the floor with the camera at a 45 degree angle – what a pain in the alignment
– but now the best I found is a focusing target you display on your PC screen
and then your live view with the resulting moiré will show perfect focus and
very quickly. Read about this target
here: [url="http://www.komar.org/faq/camera/]http://www.komar.org/faq/camera/[/url] (Alek is a great guy! Thank him if you use his targets.)
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