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07-30-2010, 06:56 AM   #16
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Jeff, I have a Tamron 17-50 that I bought new and am experiencing something similar to you. You're not alone..

07-30-2010, 10:08 AM   #17
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QuoteOriginally posted by NoMaD_PS Quote
I've got the DA 16-45 recently and it focuses right at 45mm but at 16 mm tends to focus on a backstage or infinity.
Had the same problem.
I tried to fix it in debug mode, but as I was getting near perfect focus at 16mm, at 45mm the lens was front focusing. I was pissed...
I tried it on a K-x and it worked perfectly at all focal lenghts. I later sold that 16-45 but I'm still regreting it because it was a great lens.
Very rarely I notice the same problem on my DA18-55, but it's that rare I don't worry about it.
I blame my K10D for the problem. Never had any issues on DA50-135, FA100 macro or FA50/1.4 that I used sometims. It seems to be some kind of a wide angle problem. Now I'm even scared of buying a Sigma 10-20...
07-31-2010, 11:04 AM   #18
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QuoteOriginally posted by darrenleow Quote
Jeff, I have a Tamron 17-50 that I bought new and am experiencing something similar to you. You're not alone..
QuoteOriginally posted by Mr. B Quote
Had the same problem.
I tried to fix it in debug mode, but as I was getting near perfect focus at 16mm, at 45mm the lens was front focusing. I was pissed...
I tried it on a K-x and it worked perfectly at all focal lengths. I later sold that 16-45 but I'm still regretting it because it was a great lens.
Very rarely I notice the same problem on my DA18-55, but it's that rare I don't worry about it.
I blame my K10D for the problem. Never had any issues on DA50-135, FA100 macro or FA50/1.4 that I used sometimes. It seems to be some kind of a wide angle problem. Now I'm even scared of buying a Sigma 10-20...
Thank you both for letting me know your experiences. I strongly suspect that it's a a compatibility problem.
Is it the lens, or is it the camera? Probabably a combination of both I think. My 16-45 focuses better than the Tamron, but I can still get better results if I zoom in and lock focus, then zoom out and take the picture, even with the Pentax. I've done
exhaustive tests using both with flat surface subjects. My lenses are not misfocusing due to depth of field errors. It may be a wide angle problem, but I think it depends on the configuration of the particular lens. I've never had any focus problems with the Sigma 10-20, or the DA12-24.
Thanks again for sharing your experiences. It's very frustrating.

Last edited by jeff knight; 07-31-2010 at 11:11 AM.
07-31-2010, 11:36 AM   #19
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I know how you feel. I'm a student and I don't have money to waste but I was VERY seriously considering changing systems when this happened. One time the camera refused to focus at all. Just went buzzing from minimum to intinity numerous times on a clear day and plenty of contrast. I didn't even look at it for a few days how mad I was. All of these focusing issues would probably go away if I bought a K-7, but I don't have the money... And my K10 is not treated badly in any way. It's below 7000 shots and I'm really careful about it.

Now I've saved up some money but I'm afraid to buy a new lens. I think I'll get a flash instead...

08-01-2010, 12:13 AM   #20
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To some degree I also have this on my DA 17-70. In the 17-24mm range it usually doesn't lock focus perfectly (at 100% pixel-peeping view you can see the focus is slightly off), above that range there are no issues. So if I want to use the wide end then I just turn the zoom ring to halfway (~35-40mm) or 70mm end, lock focus and turn back the zoom ring to the desired FL.
I guess this might be a problem with wide angle end of zoom lenses and Pentax AF system, I've read many people experiencing the same.
08-01-2010, 12:59 AM   #21
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This wide angle thing stinks... So what can I do? Get the body adjusted, upgrade to K-7, change systems?
08-01-2010, 12:08 PM   #22
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QuoteOriginally posted by Mr. B Quote
This wide angle thing stinks... So what can I do? Get the body adjusted, upgrade to K-7, change systems?
i have 2 tamron 17--50's, 1 k-m, 2 k-7's, still can not get a perfect combination, even with the focus adjustment on k-7. so my only way to go is to return the lenses.
08-01-2010, 02:06 PM   #23
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That sucks... I'll just stick to my kit lens for now, at least that works alright. I'll have to borrow a sigma 10-20 from a friend to see if that happens on shorter focal lenghts. So far I've tried two 16-45s and they were both off (one more than the other) and that really sucks as it was going to be a perfect replacement for the kit lens. Guess I'll have to get a sigma 18-50/2.8 or something similar...

08-09-2010, 12:26 PM   #24
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Sorry to be on the negative side, but I think I had a similar problem with this Tammy 17-50mm. I even opened this thread here some months ago. So I really don't think the upgrade to a K-7 body will solve your issue. You may go with this lens at a local dealer and try to take some test shots on a K-7 body, just to be sure...
In the end I've replaced it with a DA* 16-50mm and never had this headache since.
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