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06-02-2011, 02:02 PM   #1
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Tamron 70-200 2.8 Front Focusing BADLY

I threw caution to the wind, spent every dime I had and a few to come, and purchased a K5 and a Tamron 70-200 2.8. Both arrived today and while I was waiting for the K5 battery to charge I tried the Tamron out on my K10. I could not get good focus wide open, no matter how many times I tried.

Well, I activated the debug menu, played with the focus correction, and managed to get better focus somewhere around +100 to +120. Unfortunately, all the rest of my lenses focus best at +160, so that doesn't help. Sigh, I thought, but maybe they'll all work on the K5 and I can set the correction for the Tamron alone and all will be ok.

No such luck. I've since put the lens on the K5, found the same front focusing problem, and discovered that no amount of focus correction can compensate for this lens. Using the focus chart, and maximum compensation, the best I can do is bring the center of focus point to the 14mm line. All my other lenses are dead on or within 2mm on the chart with no focus compensation at all.

Are my only options to return the lens to B&H for another copy or to send it to Tamron for adjustment?

Thanks

06-02-2011, 02:18 PM   #2
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QuoteOriginally posted by KyPainter Quote
return the lens to B&H for another copy
This is your best option.
06-02-2011, 02:40 PM   #3
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QuoteOriginally posted by DogLover Quote
This is your best option.
Ditto.
06-02-2011, 02:55 PM   #4
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Thanks, I was debating whether I'd be better off getting it adjusted properly by Tamron (time consuming I'm sure) or risk getting another bad copy if I sent it back for replacement. Between your answers and the fact that I'm going out of town for a week where I won't be able to use my camera much, returning the lens for replacement is the option I'm taking. Maybe I'll get lucky and have the replacement waiting when I return, or at least get it shortly thereafter.

06-02-2011, 08:08 PM   #5
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AFAIK, haven't heard much of FF problem with this lens so you might just want to get another copy from B&H. I also purchased mine from B&H just a few months back and tack sharp even wide open.
06-02-2011, 09:38 PM   #6
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Focusing adjustments in camera only work up to a point. If a lens is wildly off, it is an issue with the lens itself, which must be replaced. All the best in getting it sorted out.
06-02-2011, 11:19 PM   #7
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Of course, without seeing the controlled focus test results, it's also possible this is testing error.
06-03-2011, 02:29 AM   #8
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Attached photo is a crop from the best, of perhaps forty, attempts to adjust focus on this lens. K-5 is set at maximum correction here. Any less correction, or correction the other way, moves the focus further forward. Camera was tripod mounted, 45 degree angle to chart, center focus point, flash used, shake reduction off.

I successfully corrected/confirmed a Sigma 18-50 F2.8, Tamron 28-70 and 70-300mm kit lenses, 100mm F2.8 Macro, and Pentax 18-55mm kit lens, plus verified that several fast manual lenses were focused almost exactly where the focus system suggested, far better than this, and mostly slightly back focused.

Also, I took another 60 or so photos of flowers, brick walls, and random objects using this lens with both the K-5 (before and during adjustment) and K10d and not one was in good focus and most were completely unusable. However, photos that had something in the frame (somewhere) that extended ahead of the subject always showed better focus in front of the subject. To confirm that it wasn't the camera I tried the other long lenses and I achieved sharp to acceptable focus on all the shots with the Tamron 70-300mm wide open at 200-300mm and most shots with the 100mm macro wide open, all hand held.

There was certainly room for error on my part, both in photographing and making corrections with such a long and fast lens, but I should've got at least one sharp shot just by chance. Either that or I need to sell my gear and start making mud pies for a hobby - soft is good there.

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06-03-2011, 02:51 AM   #9
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If every shot you tried was front focused and the test above it the most you could compensate for it, then it is unacceptably front focusing. The chart indicates a good 4-5mm of front focusing. You should have it replaced. The Tamron 70-200 is worth persevering to get a good copy.
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