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06-10-2015, 08:00 AM   #1
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Pentax K-50 + Sigma 18-35 F1,8

Pentax K-50 + Sigma 18-35 F1,8 Autofocus Problem
Also tested with K-5, K-3


To f/3,2 AF good. From f/3,5 front focus.
German servise:
"Lens checked; focusing checked; The lens meets Sigma factory standarts. (note, such phenomenon may occur due to the Hyperfocal distance, however, that is no fault of the lens)"
What to do ... ?


Last edited by Ramunas; 06-11-2015 at 12:34 AM.
06-10-2015, 08:42 AM   #2
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There has been talk on the forums that there is an incompatibility between that lens and Pentax cameras. Supposedly there is a focus issue that has not been addressed.
06-10-2015, 08:43 AM   #3
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should this be in the SLR lens subforum rather than K-50? Especially if the OP has tested the lens with a K-5 and K-3?

---------- Post added 06-10-15 at 11:48 AM ----------

Is this the same problem identified by the official PF Forum review?
Sigma 18-35mm Autofocus: A Second Look - Hands-on Reviews | PentaxForums.com
06-10-2015, 09:30 AM   #4
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QuoteOriginally posted by seventysixersfan Quote
should this be in the SLR lens subforum rather than K-50? Especially if the OP has tested the lens with a K-5 and K-3?

---------- Post added 06-10-15 at 11:48 AM ----------

Is this the same problem identified by the official PF Forum review?
Sigma 18-35mm Autofocus: A Second Look - Hands-on Reviews | PentaxForums.com
This is not a calibration problem.
USB Dock here does not help anything.

06-10-2015, 10:02 AM   #5
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I believe it is an incopatibility problem with that lens and Pentax cameras. It has not been addressed by Sigma to the best of my knowledge.
06-10-2015, 01:42 PM   #6
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QuoteOriginally posted by Spodeworld Quote
I believe it is an incopatibility problem with that lens and Pentax cameras. It has not been addressed by Sigma to the best of my knowledge.
Sigma reps flat out deny it, in fact. Very strange but yes, it's a known issue. The best remedy: use live view to focus at wider apertures, or focus manually.

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06-15-2015, 11:35 AM   #7
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Arg, seriously? I ordered mine yesterday and on top of that, from Germany (I live in Denmark) because I expected the quality control had improved and I've only ones had problem with a Sigma lens - also got the dock at the same time in case I'd be experience FF/BF issues.
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