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07-26-2017, 03:53 AM   #1
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AF problems on Sigma 18-250mm DC Macro HSM


I got a used Sigma 18-250mm DC Macro HSM which doesn't behave as expected:

When being zoomed to over 100mm and then going for a close-up (not even macro, over 70cm distance) in 9 out of 10 tries I can't get the lens to auto-focus properly (no matter which AF mode).
It focuses until the subject seems to be sharp, but then focuses a little more inwards, and then out again, without finding the right focus spot, so I can't take the picture. It's hard to describe, hope you get what I mean.

It seems to work a lot better when using live view.

Everything below 100mm and greater than 100mm on long distances works fine.

Am I doing something wrong here?

EDIT: camera is a K-50

Last edited by namron; 07-26-2017 at 04:12 AM.

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100mm, 18-250mm, 18-250mm dc macro, af, af focusing, dc, hsm, k-mount, macro, pentax lens, sigma, sigma 18-250mm dc, slr lens
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