New lens front/back focus problem, return or adjust?

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Daneel

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My Tamron 90mm, bought new two weeks ago, has a pretty bad front/back focusing issue. I took the same shot (on a tripod) several times in normal focus mode and in live view. The results below were consistent and the difference is not subtle. Is this bad enough to return the lens, or should I send it to Tamron for adjustment? Does anyone have experience of Tamron customer service they can share for such issues in the UK?

DSC_1351 by megapleb, on Flickr

DSC_1355 by megapleb, on Flickr
 
I'd be tempted to try your other lenses first using the same procedure but obviously at a longer distance, just to establish that it is not the camera body which is out of adjustment. I have the Tamron 90mm in both a Nikon and Canon mount and not had any issues. I did need to carry out an AF micro adjustment (= AF Fine Tune on Nikon) on my Canon 5D2 for 4 lenses, but my Tamron 90mm and Tamron 70-300mm were the only lenses that required no adjustment. Unfortunately your D5500 does not support AF Fine Tune. If you know anybody with a Nikon body, it would be useful to try the Tamron on their body. At least this would confirm if a lens problem exists.
 
HarveyM said:
I'd be tempted to try your other lenses first using the same procedure but obviously at a longer distance, just to establish that it is not the camera body which is out of adjustment..
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Thanks for your reply :)

I did that this morning with all my lenses. Most showed no difference, one showed a very minor difference. The 90mm was the only one with a significant issue.
 
If I returned every lens that needed AF adjustments then I'd only have one lens ;)

I generally like a lens to be within +/-5, but will accept +/-10. However, it needs to be consistently sharp after adjustment.
 
If my camera allowed AF adjustments, I'd agree with you, but as it doesn't I'm stuck. The lens is fine for macro where I'm manually focusing anyway, but I chose this lens because I thought it would be useful for portraits. With AF as it is, that second use is much more difficult.
 
Daneel said:
If my camera allowed AF adjustments, I'd agree with you, but as it doesn't I'm stuck. The lens is fine for macro where I'm manually focusing anyway, but I chose this lens because I thought it would be useful for portraits. With AF as it is, that second use is much more difficult.
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Ahh right, didn't realise you don't have AF adjustment. I wouldn't be happy with the results as they are tbh so would be tempted to return. Trouble is you don't know what the next lens will be like :(
Did you buy from store? If so exchange it but test the new one first. Sending the lens off to Tamron might not solve the issue as ideally it needs to be calibrated to the body.
 
I bought from Amazon so return shouldn't be a problem, though I'm very impressed with the rest of the performance of the lens so though having AF adjusted might be a better option.
 
Have you got another body you can try it on to see if it's off by the same amount? If it is then there's a better chance a lens calibration by itself will rectify the problem. If it's different then you're better calibrating the lens and camera together.

Once you send it in for recalibration I'd imagine it'd be much harder/impossible to return to Amazon if you're still not happy.
 
Not in a reasonable time frame, no. I've had the lens for two weeks already so don't want to leave it much longer if I'm going to return it.
 
Check how much aperture related focus drift this model has. Generally speaking all old wide aperture lens designs had a lot, which is why portrait photographers used to use manual focus so much. It's a problem that was ameliorated by the introduction of aspheric lens elements.
 
Hi Chris,

I'm fairly new to this and am not sure what you mean?
 
Daneel said:
Hi Chris,

I'm fairly new to this and am not sure what you mean?
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In simple terms the focus goes off when shooting wide open on wide aperture lenses, but is fine when shooting stopped down.
 
The lens is certainly sharper when stopped down, but I assumed that was because the larger DoF helped cover up the lack of focus accuracy? Also, at the same f stop, as illustrated above, in live-view the image is sharp.
 
Hrm, maybe I spoke too soon. I tried my 35mm at f/1.8 again. AF then live view.

18 AF by megapleb, on Flickr

18 LV by megapleb, on Flickr
 
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Daneel said:
The lens is certainly sharper when stopped down, but I assumed that was because the larger DoF helped cover up the lack of focus accuracy? Also, at the same f stop, as illustrated above, in live-view the image is sharp.
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It will be sharper stopped down, but the actual focus can shift when wide open.
 
Daneel said:
Hrm, maybe I spoke too soon. I tried my 35mm at f/1.8 again. AF then live view.

18 AF by megapleb, on Flickr

18 LV by megapleb, on Flickr
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Definitely better with contrast detect (liveview) than phase detect. More chromatic aberration with phase detect too. Are you testing on a tripod?
 
Yes, on a tripod.

I'm considering just buying a D7200 so I can use AF adjust.
 
It is a useful feature, especially are we are getting more and more critical of sharpness these days.
 
Having taken several more shots on my various lenses with different subjects, the difference between phase detect and contrast detect is primarily minor to non-existent. It seems the first few shots I took, for whatever reason, were prone to throwing off phase detect. Unless I'm at 100%, I can't tell the difference in most instances. Maybe I don't need to get the D7200 after all :)
 
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