why the focusing issue

lartamax

lartamax

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Name
John
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I have had this problem a couple of times but usually only noticeable with larger groups. In the image below the girl on the left is soft while the other 3 are sharper and fully in focus. Any suggestions as to cause and of course remedy is welcomed. I know there is still some pp to do but the real question is why 1 subject appears softer than the others.
Shot with canon 5d MKII Canon 24-105 L f4 in a studio set up using 4 Elinchrome lites. Ealuative metering center spot focusing using the face of one of the center subjects as a focal point.

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Hi, I would also love to know the answer to this one, I have also had issues with this?
 
what apeture were you using?

as if you were wide open at F4 then this may have caused it.

Al
 
Yeah focal length and aperture would be helpful. Probably just a DoF issue. If not it could be a more serious lens problem caused by an element shift internally, though really thats not likely. Do you notice this issue in other shots you have taken ? (not the same subject)
 
The subjects don't appear to be all on the same plane, so dof could well be the answer. Or, one of the lens elements is de-centred?
 
Sorry should have included the exif.
F8
1/125th sec
iso 100
 
Gazamonk said:
Yeah focal length and aperture would be helpful. Probably just a DoF issue. If not it could be a more serious lens problem caused by an element shift internally, though really thats not likely. Do you notice this issue in other shots you have taken ? (not the same subject)
Click to expand...

I have seen it beofre on a wedding shot but this included 8 people well spread out and the person on the extreme left was soft in comparison to the others. Otherwise the lens appears pretty sharp.

John.
 
The important thing is focal length. And at 24mm and F7.1 everyone should be sharp. I think it's a lens issue or maybe the sensor is off...?
 
it looks a bit odd, i have to admit. it would be interesting to see the full res image.

the only way you're going to know if there is a problem with your lens (or camera) is to do some controlled tests on a tripod at various apertures against a wall or something where you can clearly see whether the focus is out, it could be that the focal plane of the lens is slightly curved at the wide end and the little girl is slightly outside the dof.
 
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cuthbert said:
it looks a bit odd, i have to admit. it would be interesting to see the full res image.

the only way you're going to know if there is a problem with your lens (or camera) is to do some controlled tests on a tripod at various apertures against a wall or something where you can clearly see whether the focus is out, it could be that the focal plane of the lens is slightly curved at the wide end and the little girl is slightly outside the dof.
Click to expand...

I will try the tripod shots to see if that helps but at 24mm I would have thought it should be totally sharp. Meanwhile I have added a full res image of the girl on the extreme righ and the one on the extreme left to show the extent of the problem.

John.

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