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02-14-2011, 08:26 PM   #1
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Tamron 17-50mm f2.8 Problems

I just bought a used Tamron 17-50 f2.8 lens off ebay. It has front focus on the long end and back focus on the wide end. I've fixed this with a +60 focus adjustment in debug mode on my K-x. I think my K-x may have had slight autofocus problems that I just didn't notice before I got and tested this lens. But now with these adjustments my 55-300 lens doesn't focus perfectly. The other problem with the Tamron is infinity focus is actually past infinity. This means I can't set the focus to infinity and know that the stars are in focus like I did with the kit lens. Tamron wants $150 to fix the lens. The seller will refund my money or exchange the lens if he finds another one. I'm not mad at the seller because they've had great customer service and they are top rated on ebay. But mailing the lens back to Japan will cost money and who knows if I would get a great copy of the lens in return. I really want to keep this lens but I don't know what to do. Has anyone else experienced both back focus and front focus problems and infinity not really being infinity? If there was some hack that would let me fix bf/ff problems just on this lens and not the whole camera, that would be great.
Kevin

02-14-2011, 08:35 PM   #2
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My Tamron 17-50 is on the way. I bought one day later than you but from Prodigital2000. It's $370 but new. I will test it when it arrives.
02-14-2011, 08:39 PM   #3
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Ya I saw that one but I couldn't afford it. Mine was $298.
02-14-2011, 09:18 PM   #4
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Infinity not at infinity is quite common and often on purpose.

02-14-2011, 09:35 PM   #5
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I thought that happened mostly with telephoto lenses. Infinity was really infinity with my kit lens so that made it easy to focus on the stars at night. I take a lot of pictures of the stars and without that it's nearly impossible to focus.
02-14-2011, 11:03 PM   #6
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It's normal for AF lenses focus past infinity. Been that way for years. However, considering the high risk of misalignment and BF/FF, used Tamron lenses aren't worth bothering.
02-14-2011, 11:42 PM   #7
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I bought my Tamron 17-50mm f 2.8 from B & H Photo 3 years ago. More than 15, 000 shots later I am thrilled with the lens. I bought from a reputable online dealer, just in case there was a problem. My first copy was a good one, but you can not count on that. If you buy from a reputable dealer, you are assured of satisfaction.

Just in case, make sure you are not overly montoring the lens for focus. What I mean is, go out and shoot with it in real life--forget the silly focus charts. See how you like the real life shots, especially in natural light. So many people over analyze these focus charts to death. If you look hard enough for a problem, on any lens, you will find one.

I wish you the best of luck!!!

JT
02-15-2011, 08:14 AM   #8
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I have the 17-50 from prodig2000. Works great. I do get some BF/FF at the long end with my K-r. Wide end seems fine though

02-15-2011, 08:32 AM   #9
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Type in this video title on YouTube search bar: Re: Tamron 17-50/2.8

someone wrote in the comments that an older lens with barrel 'wobble'
due to loose screws (and tightening them) can affect focus performance.
Perhaps the OP's used E-Bay lens had these issues.

Michel

Last edited by mlatour; 02-15-2011 at 09:04 AM.
02-15-2011, 02:45 PM   #10
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Ya you're probably write Jewel I should get out and take real pictures instead of test pictures.

About that youtube video my lens doesn't wobble so I don't know if I want to do that. And I don't like that the video doesn't show him putting it back together.
04-01-2011, 08:02 AM   #11
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@krp, did you ever find a way to resolve your problem? I picked up a used Tammy 17-50 about a week or two ago from possibly the same ebay dealer as you from Japan for $298. I don't seem to have too much problems with BF/FF issues, but overall sharpness on my copy seems lacking. I really can't find any difference in out of camera RAW sharpness from the kit and the 17-50. I'm a little frustrated but I'm hoping to do some more with the lens this weekend to see what the results are.
04-01-2011, 09:51 AM   #12
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I decided to just live with the problems. I don't notice any problems with this lens with the focus adjustment set at +60 on my K-x, but occasionally my DA-L 55-300mm misses focus. The infinity focus problem wasn't actually a problem at all. My copy is noticeably sharper than my kit lens though. That ebay seller was going to let me return or exchange it, but I decided it wasn't worth the hassle. One thing I found interesting is the lens is not supposed to focus closer than 11 inches, but mine focuses at 6 inches.
04-01-2011, 10:01 AM   #13
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QuoteOriginally posted by krp Quote
One thing I found interesting is the lens is not supposed to focus closer than 11 inches, but mine focuses at 6 inches.
The minimum focusing distance is measured from the sensor plane and not from the front of the lens
04-01-2011, 10:04 AM   #14
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I also noticed how much closer mine focuses that 11 inches. I hope I can get the sharpness thing figured out because I love the 2.8 and my copy focuses quickly and accurately.
04-01-2011, 10:18 AM   #15
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QuoteOriginally posted by darrenleow Quote
The minimum focusing distance is measured from the sensor plane and not from the front of the lens
I never knew that. I guess that explains why all the lenses I've tried have focused closer than I expected.
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