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06-15-2014, 01:34 AM   #1
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Pentax lens wont AF.S focus all the time.

I have a SMC PENTAX-DA 1:3.5-5.6 18-135mm ED AL(IF) DC lens which I like the range on as a go between my tamron 17-50mm & my Sigma 150-500mm lenses. However the 18-135mm Lens drives me up the wall because the only way I can get the camera to take photos is in AF.C. As in AF.S it only focus at a few points down the zoom & when it doesn't focus the focus indicator just blinks & the camera won't take a photo! Any Idears? ???

06-15-2014, 01:48 AM   #2
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QuoteOriginally posted by tallpaulk9 Quote
I have a SMC PENTAX-DA 1:3.5-5.6 18-135mm ED AL(IF) DC lens which I like the range on as a go between my tamron 17-50mm & my Sigma 150-500mm lenses. However the 18-135mm Lens drives me up the wall because the only way I can get the camera to take photos is in AF.C. As in AF.S it only focus at a few points down the zoom & when it doesn't focus the focus indicator just blinks & the camera won't take a photo! Any Idears? ???
Hmm, are you shooting in really low light? At 135mm the maximum aperture is F5.6, which might lead to problematic performance unless you're using a K-5 II or K-3.

Another possibility could be front or back focus. Have you tested your lens to see if the AF is off / needs adjustment?

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06-15-2014, 04:36 AM   #3
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It work ok in AF.C and obviously in Manuel mode. It plays up anytime, could be bright as anything or could be cloudy. And it does it anywhere through from 18mm up to 135mm and even on a wide aperture or a medium or small.
06-15-2014, 06:32 PM   #4
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You didn't even mention which camera model.

Reset to factory defaults in the menu. Also update the firmware, if available. Even re-install the latest firmware if necessary. Remove lens, re-seat it, and see if anything changes.

06-16-2014, 07:11 AM   #5
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QuoteOriginally posted by DSims Quote
You didn't even mention which camera model.

Reset to factory defaults in the menu. Also update the firmware, if available. Even re-install the latest firmware if necessary. Remove lens, re-seat it, and see if anything changes.
O I'm sorry I miss that out on this forum post!!
I have a Pentax K 7 and a K5.
Both have been updated and defult settings reset, Lens has been reseated of many occasions, electrical contacts have been cleaned again on many occasions.
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