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01-04-2013, 08:56 AM   #1
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K30 and tamron 17-50 f2.8

I recently upgraded to K30 from K10 and Kr. I have two lenses that cover all of my needs - tamron 17-50 and da70. With K10 and Kr both were spot on, didn't need any focus adjustment. Now, when I use tamron with K30, I notice that it front focuses at longer end, and even -10 correction in the menu is not enough. At the same time, at 17mm is ok without any correction, but not all the time - sometimes I get backfocus So, is it possible that K30 has some different AF routines and messes up my tammy so it becomes almost unusable @f2.8? Anyone had the same experience?

01-04-2013, 12:43 PM   #2
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The focus adjustments needed may vary by camera, so yes. But at the same time, it's weird that -10 correction isn't enough. Have you tested the AF with a test chart?

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01-04-2013, 04:48 PM   #3
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Not with the test chart yet, but I took a ruler and what is more important, I took a lot of pictures and saw missed focus. I will do the test with the chart.
It is a bit frustrating - first I had K10, and it was backfocusing a lot. So I made correction in the debug menu, and all the lenses were spot on.
Then my Kr had problems with thungsten white balance. It was also very annoying.
Now the brand new Pentax camera, that should be one of the best cameras in the class out there, messes up my focus again.
What is going on here with Pentax, why can't they make a camera without issues? Or am I just that lucky...
01-05-2013, 12:23 AM   #4
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That Tamron is THE no.1 lens for people to have AF calibration issues with on Pentax. No idea how it fares on other brands of camera.

01-05-2013, 01:21 AM   #5
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Yes I know that. I was hoping that my copy of the lens will not have these issues with the brand new K30, especially because I had no issues with previous bodies. I always believed that I have a perfect copy
Can I have some hopes that some future firmware upgrades could solve this problem? I have a feeling that Pentax couldn't care less about focusing problems with third party lenses
01-05-2013, 09:29 PM   #6
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QuoteOriginally posted by SteveB Quote
That Tamron is THE no.1 lens for people to have AF calibration issues with on Pentax. No idea how it fares on other brands of camera.

It fares just as badly, just search for it and you will see.

The low price sucks in user after user and the complaints keep rolling in about focus variations at different zoom lengths.

Ray
01-05-2013, 09:35 PM   #7
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QuoteOriginally posted by hegedus Quote
Yes I know that. I was hoping that my copy of the lens will not have these issues with the brand new K30, especially because I had no issues with previous bodies. I always believed that I have a perfect copy
Can I have some hopes that some future firmware upgrades could solve this problem? I have a feeling that Pentax couldn't care less about focusing problems with third party lenses
Why would Pentax fix a problem with a Tamron lens, especially if the fault lies with the lens?

I wouldn't touch this Tamron lens at any price. On the other hand, my Sigma 17-50 f2.8 is tack sharp on my K5 with no adjustment, and my DA* 16-50 focused fine as well, although it is not quite as good as the Sigma. I had a very inexpensive Sigma 18-50 f2.8 that was a pretty good performer as well, and also quite small. They come up once in awhile used for not much money

Dump the Tamron and get something else.

Ray
01-06-2013, 12:29 AM   #8
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I used the Tamron 28-75 2.8 on my K-M and didn't notice any kinds of issues with it, but it might be a little off on my K30 as well. I've just gotten mine and started running through it.

01-06-2013, 06:23 AM   #9
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QuoteOriginally posted by Ray Pulley Quote
Why would Pentax fix a problem with a Tamron lens, especially if the fault lies with the lens?
This is my point too. The only odd thing about it is that my lens was very good on other bodies, so it seems to me like Pentax deliberately did something with K30. If this is true, your question about doing something about improving performance to non Pentax lenses - they did exactly that, but to make things worse, not better
Oh well, maybe I have gone too far, maybe my lens is really not that good as I think. It is true that I didn't check focus accuracy for a very long time, but in daily use I did not see any problems with it.
01-06-2013, 06:48 AM   #10
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QuoteOriginally posted by hegedus Quote
I recently upgraded to K30 from K10 and Kr. I have two lenses that cover all of my needs - tamron 17-50 and da70. With K10 and Kr both were spot on, didn't need any focus adjustment. Now, when I use tamron with K30, I notice that it front focuses at longer end, and even -10 correction in the menu is not enough. At the same time, at 17mm is ok without any correction, but not all the time - sometimes I get backfocus So, is it possible that K30 has some different AF routines and messes up my tammy so it becomes almost unusable @f2.8? Anyone had the same experience?
Guess I got lucky. My Tammy 17-50 is razor sharp with my brand new k30. I couldn't say the same with results from my kx.
01-06-2013, 01:05 PM   #11
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Well, I did some additional tests. First thing I did is to reset the camera and all custom settings, so that now I have no focus correction. Surprisingly the lens performs very good to excellent. Only focal length where I see some problems are from 17 to cca 24mm , where I see backfocus. I can live with that Also, at daylight this fault is not so expressed. So, it seems that my tammy is just what it is - a cheap lens with great performance followed by some weaknesses.

Last edited by hegedus; 01-07-2013 at 01:14 PM.
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