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06-15-2008, 06:47 AM   #1
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Protracted and boring, but opinions sought please.

Well everyone, im a Pentax Fan!

I owned the 100d Super and was so impressed i soon moved up to the K10D. With my K10 purchase i also took a Sigma 24-70 and the 70mm macro. I kept my kit 50-200 from my K100 Super purchase.

From day one i had AF issues with both the Sigmas and no probs with the pentax on the new body. I happen to be lucky in that the Sigma service centre is in my area so very close to home.

I took in the 24-70, they adjusted and reported fixed. Get home still 12mm FF. Returned and they dicovered something the guy claims they have never seen with a Sigma lens before.

The AF changes from a FF issue at F2.8 to BF issue at F11. Both the service guys are dumbfounded. They ordered a new CPU. After adjustments the same problem continues.

I have been present during these attempts to fix the problems and have watched with keen interest. The solution now is that they have asked me if im prepared to exchange the lens for another, however there are no copies of the 24-70 in the country and they expect non for a while. So i have opted for the Sigma 18-50 2.8 ex hsm.

The service guys say that it could be that because both the Sigmas are designed for a FF sensor and the AF problem could lie there.

Thai is what worries me, i have to go again tomorrow morning to get the 18-50, and they told me to bring the 10D so they can calibrate the lens. They say they think the problems will vanish with the 18-50 because its a DC lens. BUT, what if it does not go away! Thay are going to blame the 10D for the AF issues. But i know its not the body because the Pentax 50-200 has no issues on the K10.

What do you think? Is it the K10 Or Sigma? If they decide its the K10 what can i say in its defence? Should i get hard line with the guys if they try and go that way?


06-15-2008, 07:31 AM   #2
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The Pentax camera works with the Pentax lens. The Sigma is the issue IMHO. Sigma has not extactly been completely without fault in their design & manufacturing.

Do you still have the K100D Super to test the lenses on? Can you borrow one for a double check?

If you get the same issues on a different model camera, the lenses are obviously at fault.
06-15-2008, 07:58 AM   #3
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hi TourDeForce

unfortunately i have no second body and i know no Pentax owners in my area.

06-15-2008, 09:06 AM   #4
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> unfortunately i have no second body ...

Ask the service center to bring out other Sigma AF lens to provide additional data point, that should determine whether your K10D is the problem. Alternately, can ask them to bring out other K10D and mount your 50-200, as well as your Sigmas. Make sure you mark your gears so they are not confuse with theirs!

At any rate, the Sigma 18-50 is not a shabby lens. It is HSM and a MACRO. Why not consider eliminating the overlap at 70mm?

06-15-2008, 10:19 AM   #5
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You are right the 18-50 is a solid choice. As far as Pentax anything at the service center goes, its a no no. This is a seven week saga already and im sure they would have pulled out any Pentax bodies or Sigma pk AF lenses long ago. Jees, it just shows you how biased this industry is toward Canon and Nikon.


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