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11-06-2010, 08:29 PM   #1
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Camera problem?

Can a camera cause a picture to be fuzzier on one side, not the lens? I know that's usually an indication of a decentered lens, but suddenly I'm wondering if perhaps a camera with a sensor that's out of alignment or something might create the same problem

Today I was out shooting a sunrise with a K20 for the first time in a very long time, and ran across this problem.

Today I had the DA*200 on the K20 and a wide angle on the K7, shooting with both cameras in months. Reviewing the shots, the K20's shots were blurry on the right, sharp on the left. Most noticeable when shooting the camera in landscape aspect - when shooting vertical shots I couldn't tell (right was in the sky). I'm absolutely positive the lens isn't the problem - I use it often with the K7 and have never seen anything like this.

When it was my regular camera I had reason to suspect that my DA 50-135 (at that time my most used lens) might be decentered - occasionally (not always) I'd see the right side fuzzier than the left side. My main camera is a K7 and I had forgotten all about it, but I don't use the 50-135 very much any more.

Now I'm beginning to think that the problem isn't the lens at all - could it be the camera? I've uploaded a full sized shot at: http://mtngal.zenfolio.com/img/s9/v14/p698805318.jpg . What I noticed is the tree line on the ridges. Both right and left ridges are about equal distance away - over a mile. I would have expected that the trees on the ridges should be equally sharp (or not sharp), but the left side looks noticeably sharper to me than the right. Can someone look at it and let me know what they think - whether I'm dreaming or what.

I know that this isn't that great of a test, but it's the same thing I saw with the DA*50-135. Is it possible this might be a camera problem? Or am I just imagining the whole thing (my eyes aren't the greatest at times). The only thing I'm sure of is that my DA*200 doesn't do anything like this with the K7.

11-06-2010, 09:45 PM   #2
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Are you sure the two mountains were equidistant? If not, then you can't be certain that there's something wrong with the camera. You can easily re-create this test indoors, though, with two similar objects placed on either sure of the frame. Then, stop your lens down to F16, put the camera on a tripod, and see if there's still misalignment. BTW, that's a beautiful photo!

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11-06-2010, 10:04 PM   #3
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It may not be the full story but I am certainly seeing lots of chromatic aberration on the right hand side, particularly at the extreme edge where the background is lighter. Also some possible out of focus - 200mm and f4 means narrow DOF after all.

But your issue is the easiest thing in the world to sort out with a few test chart shots, as Adam suggests. I like to use the ISO 12233 Test Chart, downloadable here:
http://www.graphics.cornell.edu/~westin/misc/ISO_12233-reschart.pdf

If it's the body, your issue should be visible with any lens.
11-07-2010, 08:21 AM   #4
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I like that chart - I'll print it tomorrow at the office, where I have access to larger paper.

Thanks for the responses (it was a nice sunrise). Now that I look at the pictures, it's possible the right ridge isn't the one I thought it was - it may be a mountain that's probably a half mile further away than the one on the left, which is just over a mile. I was going to post another, similar shot taken with the K7 and FA 77 that doesn't show any differences between the sides (http://mtngal.zenfolio.com/img/s10/v2/p400346118.jpg ) but I'm not sure that's helpful - different focal lengths handle distances differently and if the right ridge is the further one, it would make too much of a difference to be a useful comparison. I'll take both cameras out and a collection of lenses and take a bunch of direct comparison shots at various distances. I may be jumping to conclusions.

But it IS possible for something like this to be caused by a camera, not just a lens?

11-07-2010, 08:56 AM   #5
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A sensor plane alignment quality problem does occur, very rarely, and more likely an assembly defect out of factory, in which case you would have spotted it a long time ago, or if the camera has taken a hard knock (I'm assuming this is not a new camera and hasn't had any physical damage ?)

I suspect this is a Depth of Field issue , as others have pointed out. It should be straightforward to confirm by taking a shot comprising every day objects at various distances in decent lighting or with flash.
11-07-2010, 11:20 AM   #6
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Well, I'm more confused than before. I hate taking comparison shots - I always forget something. Finally put both cameras at the same ISO, used M and the same shutter speed and f8 aperture.

I did not see much difference between right and left sides when shooting my shaded house siding with a very old uncoated lens (K-mount Takumar 135, while it has lots of faults it's a very sharp lens when used on a dSLR). There wasn't much real difference between cameras. From these two pictures I would say that both cameras are working fine, and this 1980 kit lens is sharper than many modern lenses.

Then I used the DA*200 on both cameras, shooting a ridge line that's a mile across a valley. I first looked at the K7's picture - no particular difference between right and left side of the picture. Looked at the K20 and immediately noticed it was blurrier all over - forgot to take SR off (using tripod). Turned off SR, camera settings were still the same, retook it. Picture a bit sharper but not that much more. Could have been that I used a wireless remote the first time and forgot to use it the second time, but the shutter speed wasn't that slow and I have a sturdy tripod. I only a slight difference between right and left (what I had noticed in the sunrise pictures), but the K7 was noticeably sharper.

I noticed the same thing with the earlier pictures, though the cameras metered differently. While the Av was the same (f4 and f8), in Av mode the cameras chose different shutter speed/ISO combinations to get the same exposure - do I ever hate shooting comparisons!

At this point I'm thinking that the sunrise picture problems are related to distance differences and f4. That's good news indeed! But now I'm curious about the over-all differences between the K20 and K7 - when I first got the K7 I thought the pictures from the two cameras were about the same when it came to sharpness. Wonder if the K20 isn't quite auto-focusing right with the DA*200? Sigh - more things to check - yuck!
02-01-2011, 03:31 PM   #7
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I'm having similar problems, occasionally, with sharpness issues on one side which can't easily be explained by a decentred lens. For example my 16-45 gives good overall sharpness when I take the picture in landscape, but I get images which are soft towards the top in when the camera is held portrait format. The degree of softness seems to be influenced by which way round I hold the camera!

I have been playing with a DA21mm, and noticed a similar effect where holding the camera in portrait position gave me softness at the top of the image when I hold the camera one way round but not the other. (There is no corresponding softness at the bottom when the camera is rotated 180 degrees). Landscape format pictures are fine. Looks like I need to do some exhaustive tests to determine where the problem lies.


Last edited by ihasa; 02-01-2011 at 03:49 PM.
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