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Problem with D300 focus error

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KennyKB

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I have a puzzling problem with occasional focus error with D300 and Tamron 17-50mm f2.8 VC. Set to AF-S and auto-Area AF with focus priority release, 1 in 10 shots seem to miss focus. I would understand if the auto-Area AF selected a near point to focus on but nothing appears to be in focus. How can the shutter be released with nothing in focus when the shutter release is focus priority? There's also no sign of camera shake.

Am I doing something wrong? Your comments are appreciated.







 
I have a similar problem with my Tamron 10-24. On my lens the problem only occurs at wide angle. Your shots are all at max. wide angle. Make a test if the focus failure happens at 50mm as well.

Unfortunately 1 out of 10 is difficult to explain to the service center. If you find a procedure were you can reliably reproduce the problem this might help very much to find the problem.
 
I can't say if you are doing anything wrong but you are right, those images are out of focus but I can't say why. The two images contain very little focus which may have confused the camera. It is also possible that something is wrong with your lens, I suggest you take a few test shots using tripod. I don't have that lens but perhaps you should post your question on the lens forum, you might get more replies and advices over there.
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http://www.dpreview.com/Galleries/1336313410/photos

My blog:
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Other shots of the same scene comes out in perfect focus using the same settings. It's hard to reproduce as it only comes out intermittently. My 1 out of 10 is based on the number of out of focus shots compared to how many I took in one session only so it may not be a representative figure. I've had sessions where it doesn't happen.
olyflyer said:
I can't say if you are doing anything wrong but you are right, those images are out of focus but I can't say why. The two images contain very little focus which may have confused the camera. It is also possible that something is wrong with your lens, I suggest you take a few test shots using tripod. I don't have that lens but perhaps you should post your question on the lens forum, you might get more replies and advices over there.
--
My Nikon 16-85mm gallery:
http://www.dpreview.com/Galleries/1336313410/photos

My blog:
http://www.olyflyer.blogspot.com/
Click to expand...
 
i discovered the same problem on my newly acquired tamron 17-50 VC.

It seems that with this lens focus points will almost always be chosen from the extremities and not a single point in the center. If you set it to Single Point, then the lens is going to focus properly.

This does not happen with the old version or other Nikon Lenses.

I send a mail to Tamron Europe and they advised me to send it back. I went back to the store where i purchased it (Megapixel cz) and tested one more copy and on a different body (D300S)

All combinations D300,D300S +3 Tamron 17-50 VC copies had the same issue.

I sent mine back on 28 Jan, still no word from the store.

My advice is to send it back.

Edit: this happens only at wide (17-20mm) and 2.8 for obvious reasons.

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Thank you for your reply gDaniel. Was your problem with auto area AF as well? Do you mean to say if you use single point AF and select the focus point the problem disappears? Do let us know if the store resolves your problem.
gDaniel said:
i discovered the same problem on my newly acquired tamron 17-50 VC.

It seems that with this lens focus points will almost always be chosen from the extremities and not a single point in the center. If you set it to Single Point, then the lens is going to focus properly.

This does not happen with the old version or other Nikon Lenses.

I send a mail to Tamron Europe and they advised me to send it back. I went back to the store where i purchased it (Megapixel cz) and tested one more copy and on a different body (D300S)

All combinations D300,D300S +3 Tamron 17-50 VC copies had the same issue.

I sent mine back on 28 Jan, still no word from the store.

My advice is to send it back.

Edit: this happens only at wide (17-20mm) and 2.8 for obvious reasons.
Click to expand...
 
In your first image, it looks to me like best focus is far in some parts of the image (top and upper left) and near in other parts (bottom and right), implying a decentering or misalignment in some element involved in the focus mechanism. It could be that when the autofocus mechanism of the lens is moving toward rear or toward front that the alignment of elements is different and focus is achieved at different distances depending on this alignment. With misalignment, the system would be confused about whether a point in focus is actually the closest.

In the second image, it looks to me like the camera focused on one of the closer areas on the right with high contrast, so I suspect it's the camera picking one of those areas to focus on. This type of subject is very difficult for an autofocus system, and as I understand it wide area AF will pick a close point in preference to a far point.

Do you have the focus point illumination turned on? If so, this should tell you where the camera is focusing in this focus mode, and you can do some tests and see if that is the point that is in focus.

I agree that there is no evidence of camera movement in these photos (it usually looks different than out of focus images), but it's possible that at 1/60 even with this wide angle that some camera motion or vibration could produce an image of somewhat lower sharpness without giving clear evidence of camera movement.

Good luck with getting this resolved. At least it's one out of 10 with a focus problem instead of 9 out of 10.
--
Pat
 
Three 17-50 VCs on two different D300 bodies and a D5000, and I have the exact same problem as you. If I use AF-C, it gets a little better.

None of my other lenses miss focus, so it must not be the bodies.I will be sending my 17-50VC back to the factory and see what they come up with. It's a shame -- it's a fantastic lens when it focuses right.

I also have a problem where it hunts at 50mm wide open in low light.
 
Pat, thanks for your response but I think it may not have anything to do with the scene. Here are 2 shots of the same scenes taken with the same parameters and they are sharp.

I'm more incline to believe it may be a hardware problem with this particular lens/body combination as others have experienced. Possibly a communication problem between the lens and body?
PatMann said:
In your first image, it looks to me like best focus is far in some parts of the image (top and upper left) and near in other parts (bottom and right), implying a
Click to expand...






 
Yes, it's a fantastic lens when it focuses right. I really like its sharpness wide open. I sold off the non-VC model to get the VC. I hope Tamron can find a fix for it. In the meantime I will use single point AF instead of auto area AF.

I've also had occasions where it refuses to focus in low light using single point AF but it focus more reliably with auto area AF so it's a choice between a rock and a hard place.
goldenpiggy said:
Three 17-50 VCs on two different D300 bodies and a D5000, and I have the exact same problem as you. If I use AF-C, it gets a little better.

None of my other lenses miss focus, so it must not be the bodies.I will be sending my 17-50VC back to the factory and see what they come up with. It's a shame -- it's a fantastic lens when it focuses right.

I also have a problem where it hunts at 50mm wide open in low light.
Click to expand...
 
KennyKB said:
I have a puzzling problem with occasional focus error with D300 and Tamron 17-50mm f2.8 VC. Set to AF-S and auto-Area AF with focus priority release, 1 in 10 shots seem to miss focus. I would understand if the auto-Area AF selected a near point to focus on but nothing appears to be in focus. How can the shutter be released with nothing in focus when the shutter release is focus priority? There's also no sign of camera shake.

Am I doing something wrong? Your comments are appreciated.
Click to expand...
I had a similar problem 5 months back with my D300 and posted the following:
http://forums.dpreview.com/forums/readflat.asp?forum=1039&message=32877649

My behaviour was much more severe with 60% of my shots being soft or out of focus. The majority opinion from the forum was that it was camera shake but when I took the camera to the local shop, they also observed the issue with a different 70-200 f/2.8 and 50mm f/1.4. So with mine, it was definitely a body issue and not a single lens.

Bottom line is the shop recommended sending the body back to Nikon where the repair report stated "Upgraded auto-focus system and adjusted internal flash(probably unrelated to the AF issue). D300 has worked fine ever since.

Can you see either through NX or Lightroom whether the system actually focus locked?
 
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