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02-01-2014, 08:31 PM   #1
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Tamron 17-50 f/2.8 softer to one side

I think I may have to send one of my favorite lenses in, and that makes me sad, but I'm trying to understand what happened and if it is worth getting it fixed or buying a new one. I'm talking about my Tamron 17-50 f/2.8. I noticed that pics taken with it toward the end of last year and so far this year that unless I stop it down to f/8 or so it is really soft at one side, and I mean very blurry and out of focus. What in the world could I have done, and is it worth fixing or should I simply get a new one? Here's two example pics:

As you can see on the right side of the picture the focus falls off badly. I sharpened as much as I could to salvage it, but there were other that I had to toss because of this.

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On this one you will notice her feet are out of focus. Again, it corresponds to the right side, but I had the camera turned sideways.

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02-01-2014, 08:54 PM   #2
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Looks like a tilted element, service for sure.
02-01-2014, 09:03 PM   #3
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Thanks. Now that I know what may be wrong with it I wonder how in the world I did it so I wont do it again.
02-01-2014, 11:38 PM   #4
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I'm Sorry but this really seems like operator error.

There is nothing sharp in these images at all.

02-02-2014, 12:25 AM   #5
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I had this problem with my Olympus XZ-1. At first I thought I was seeing things, until I noticed it was always on the same side and showed up mostly at wide apertures.

I sent it in for service, and they returned it slightly biased toward the other side. But now it was close enough to not bother me much anymore.
02-02-2014, 12:27 AM   #6
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QuoteOriginally posted by Corto-PA Quote
I'm Sorry but this really seems like operator error.

There is nothing sharp in these images at all.
Well i suspect these are high iso images (there's no exif). Sharp or not, at least for me there's clearly a difference between left and right side, right being worse. You could send maybe, if there's warranty left, some examples to Tamron service, both in good and bad light and at different f stops.
02-02-2014, 12:39 AM   #7
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I would first try taking a picture of a flat test chart to confirm your suspicions.

Also, this behavior seems in line with what I have read about the lens on Photozone: Tamron AF 17-50mm f/2.8 SP XR Di II LD Aspherical [IF] (Canon) - Review / Test Report - Analysis

(scroll to the diagram right before the MTF charts)

Though it seems a little more pronounced in your case.

If you still want to send it in, get an estimate first. Depending on how much it is, it might be worth it to get a new one or good condition used copy.
02-02-2014, 08:59 AM   #8
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QuoteOriginally posted by Corto-PA Quote
I'm Sorry but this really seems like operator error.

There is nothing sharp in these images at all.
They are high ISO images under crappy lighting, and when reduced in size using Prish Resizer it eats away at some of the sharpness and color. I wasn't looking for critique of what amounts to snapshots taken from a dealer booth at a convention though, I was looking for reasons for what I was seeing, and recommendations on what to do about it.

02-02-2014, 09:26 AM   #9
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I had exactly the same issue with a Tamron 17-50 a few years ago. (Somewhere in PF there is a thread I put together about the problems I had with that lens).

I bought it new, but the right hand side was very soft, the image was optically distorted more than was normal, and the purple fringing was really, really bad.

I tested it pretty carefully and then sent it back with a report on the problems to the dealer and got a new copy sent to me. The 2nd lens has been flawless.

My dud lens was badly de-centred, possibly as a result of receiving a knock or two in transit. A lens element (or two) only need move a fraction of a millimetre to send a lens out of whack.

Send it in for repair or adjustment. It may only be a loose screw somewhere.
02-02-2014, 12:03 PM   #10
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QuoteOriginally posted by VoiceOfReason Quote
They are high ISO images under crappy lighting, and when reduced in size using Prish Resizer it eats away at some of the sharpness and color. I wasn't looking for critique of what amounts to snapshots taken from a dealer booth at a convention though, I was looking for reasons for what I was seeing, and recommendations on what to do about it.
The reason you got the reaction you got was that if you want to test for sharpness across the frame, you need to take lots of test shots of suitable subjects at a variety of distances and focal lengths. You'll need that to compare before/after if you send it in to Tamron. Given the length of the warranty it's probably still within the warranty period, but if you send in the pictures you posted, they're somewhat likely to dismiss your complaints. I sent resolution test chart images, and other controlled subject images, with another lens, and was still ignored, but at least you've got a chance if it appears you're doing as scientific a test as possible.

Also remember that this lens has severe focus field curvature at wider settings, so you're really just looking for the corners to be equally soft at wider focal lengths, certainly not to be sharp.

So make some test with a suitable subject, heavy tripod, no SR, both autofocus and manual, preferably two different camera bodies. Preferably you'd have some similar results from when you first bought the lens - I saved mine from when I bought my 17-50 - so you can compare the results you're getting now.
02-02-2014, 03:17 PM   #11
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I am sure I have them somewhere. I will look through my files. I keep everything, so they should be coded by date.
02-11-2014, 05:56 PM   #12
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I sent it in to Tamron with a quote of 155 for a repair in case it was something I did, but they will check and make sure that it is warrantable first, and if so they will repair it.
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