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11-10-2010, 10:25 PM   #1
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Tamron 70-200mm AF Inaccuracy

As I get more interested in this lens, I am doing a bit more research to find more info. There are two reviews - both talks highly of IQ but badly of AF inaccuracy. So would like to know the real-life experience from the users

Links to both the reviews

QuoteQuote:
Tamron SP AF 70-200mm Di LD (IF) Macro Lens Review: 6. Conclusion & samples: Digital Photography Review
...
But perhaps the biggest problem we encountered was a tendency for the lens to mis-focus, seemingly at random and disturbingly frequently, such that F2.8 shots in particular were often not critically sharp
QuoteQuote:
Tamron 70-200mm f/2.8 Di LD (IF) Macro Lens Review
...
Of course, the Tamron 70-200mm f/2.8 Di Macro Lens' very good image quality will only be seen in a properly-focused picture. Unfortunately, AF accuracy is the biggest problem area for this lens. Both Tamron 70-200mm lenses I've had appeared to be properly autofocus-calibrated, but neither autofocused consistently accurately. My percentage of properly-focused shots is highest at 70mm and lowest at 200mm. The accuracy percentage was low enough to raise my red flag for critical shooting situations. The accuracy percentage was even lower in low light situations. An indoor available light event and portraits in the shade are examples of situations that delivered especially low AF hit rates for me. Narrowing/stopping down the aperture increases DOF (Depth of Field) and therefore increases the keeper rate from this lens. But this of course negates a definite attraction of this lens - the constant max f/2.8 aperture.
...
If your tolerance level for OOF (Out of Focus) shots is higher than your budget, this might be the right lens for you.


11-11-2010, 09:59 AM   #2
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I read all of that when researching my purchase, bought it anyway, and haven't seen anything of the sort.
11-11-2010, 12:39 PM   #3
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I also knew about this apparent issue prior to my purchase and personally have not been able to replicate it.
I have used it for numerous weddings, portraits and some landscapes, and it consistently gives me accurately focused images - and also has the wow factor...
11-11-2010, 12:47 PM   #4
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I have no problems with mine.

11-11-2010, 01:30 PM   #5
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I have the Tamron 70-200 on my K10 and it's right on the money relative to focus. Only thing I have against this lens is the weight, but that's what I would expect from a lens with that much glass. Great lens.
11-11-2010, 02:14 PM   #6
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not a problem with focusing from my first pictures, some pretty good results

here is a link with 6 pics
11-11-2010, 03:30 PM   #7
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When it comes to reviews that talk about AF accuracy, you can safely ignore comments about it with regards to Canon bodies especially (such as the review above). It is my understanding (someone please correct me if I'm wrong) that Canon doesn't license their AF protocol, so third-party lens makers have reverse-engineered the protocol, resulting in what is sometimes less than stellar AF performance of non-Canon lenses on Canon bodies. I have read about how third party lens makers over the years have had to offer "re-chipping" services for their Canon mount AF lenses as new bodies have come out and the protocols have shifted and the reverse-engineered lens routines have needed to be updated, and the in some cases outright haven't worked on newer bodies.

To my knowledge this has never been an issue on Pentax, though I don't know whether this is a case of Pentax not minding licensing their AF protocols, or whether the Pentax AF system has been reverse engineered better and/or hasn't undergone as significant changes as Canon's has over time.
11-11-2010, 03:40 PM   #8
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Uh, I owned one for a few weeks... AF was spot on as long as the subject was within 50 feet (an approx. guess) but beyond that, it was off.

(I checked to make sure that it wasn't caused by BF/FF issues)

11-11-2010, 08:36 PM   #9
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QuoteOriginally posted by Ubuntu_user Quote
Uh, I owned one for a few weeks... AF was spot on as long as the subject was within 50 feet (an approx. guess) but beyond that, it was off.

(I checked to make sure that it wasn't caused by BF/FF issues)
Does it happens on all the focal length and apertures? or just 2.8?
11-12-2010, 07:51 AM   #10
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QuoteOriginally posted by yusuf Quote
Does it happens on all the focal length and apertures? or just 2.8?
It did it at all focal lengths and apertures.
11-12-2010, 08:34 AM   #11
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QuoteOriginally posted by Ubuntu_user Quote
It did it at all focal lengths and apertures.
hmm, that's disappointing. We seems to be running out of options for 200mm? Tamron already have well-know sticky aperture issue and now this one. Sigma does not compare good in IQ at longer end (or am I wrong?)
11-12-2010, 08:42 AM   #12
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I bought the Tamron 70-200mm f/2.8 about six months ago and have had no issues with focus or sticky aperture, including all-day shooting at an airshow and all-day shooting during a parade of bands from around the world, for what that's worth.
11-12-2010, 08:51 AM   #13
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QuoteOriginally posted by yusuf Quote
hmm, that's disappointing. We seems to be running out of options for 200mm? Tamron already have well-know sticky aperture issue and now this one. Sigma does not compare good in IQ at longer end (or am I wrong?)
I think you maybe be worrying too much. If you look hard enough, read enough posts, you can find small pockets of issues with almost any lens. People tend to forget about the 95%+ of copies of a particular lens that have no issues at all and focus on the <5% of copies that do. Obviously you could get a bad copy of the 70-200 (or any lens), but if you avoid every lens that has had an issue, you're going to be limiting yourself to a lot fewer lenses to choose from.
11-12-2010, 12:16 PM   #14
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Yusuf, you're looking for any sign of 'fault' to put you off buying this lens...
The Tamron is excellent, period.

If you want 200mm of reach and are happy with a prime, I'd suggest a DA* 200, but otherwise the Tamron (and the Sigma) are the only other f/2.8 AF lenses in this telephoto range. And both do the job but I do prefer the sharper results from the Tamron more.
11-12-2010, 12:23 PM   #15
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QuoteOriginally posted by Ash Quote
Yusuf, you're looking for any sign of 'fault' to put you off buying this lens...
The Tamron is excellent, period.

If you want 200mm of reach and are happy with a prime, I'd suggest a DA* 200, but otherwise the Tamron (and the Sigma) are the only other f/2.8 AF lenses in this telephoto range. And both do the job but I do prefer the sharper results from the Tamron more.
@Ash, I am just a bit more conscious because it will be more difficult to get service here if something is wrong (anything to do with Pentax and we have absolutely nothing). Actually I generally don't, but then I read some extra -ve reviews, it was obvious to get worried
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