Confused!!! Does my 24-70 misfocus (4 pics)?!?

Started Mar 18, 2009 | Discussions thread
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Henrikw Contributing Member • Posts: 734
Confused!!! Does my 24-70 misfocus (4 pics)?!?

I wish I could praise my 24-70, but unfortunately I never know when I get a sharp picture when shooting at 24mm (mostly sharp at 70mm) - it seems to be completely random, so I decided to have it re-calibrated.

Got it back today, and to my great disappointment I get the same results. Here are my test results to show the problem.

All shot with my 40D on a tripod and self timer. Flash used on all pictures (100% crops):

1/200s f/2.8 at 24.0mm iso100

Slight front focus, but I guess it looks acceptable

1/200s f/5.6 at 24.0mm iso400

Spot on

Now take a look at these shots - again on tripod. Focus on the FRONT box:

1/200s f/2.8 at 24.0mm iso200

This looks like severe back focus to me - there are 20 inches between the boxes

1/200s f/5.6 at 24.0mm iso400

Also noticeable at 5.6

So, you probably understand my confusion - the focus test turned out ok, but shooting in other conditions appear to show that the lens is back focusing

Any ideas what can cause this?!? The test results I get are consistent (spend 4 hours tonight!!!)


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Canon EOS 5D Mark II Canon EOS 5D Mark III Sony a6000 Canon EF 85mm f/1.2L II USM Sigma 15mm F2.8 EX DG Diagonal Fisheye +5 more
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