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07-09-2011, 11:26 PM   #1
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645D Erratic Dial Behavior

Hey Gang,
I'm a new 645D owner and while i absolutely love the camera i've been experiencing some erratic behavior with the rear dial when trying to change apertures and iso's at times when trying to change it an aperture it goes the opposite direction of the way i'm moving the dial with the in ability to dial down to the lowest aperture without having to turn the camera off and back on again.

Wondering if anyone has experienced the same issues and if so had a work around for it.


07-09-2011, 11:47 PM   #2
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I hate to scare you, but usually stuff like this means the dial is faulty and has to be replaced

Do make sure it's the hardware and not the software, though- for example, in P mode, you can't dial in an aperture setting that would under-expose the image given the available light.

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07-10-2011, 12:13 AM   #3
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Hey Adam,
Thanks for the quick response, yeh i'm starting to fear that might be the case ;-( It seems to only be the rear dial, it jumps around when trying to switch Apertures and ISO's. At first it was just slightly annoying now it's driving me mad.

Wondering if anyone else has had this problem and if it could possibly be software related.

07-10-2011, 12:18 AM   #4
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I just found this over on Lloyd Chambers website seems as if i'm not the only one with the problem. ;-(

Dial functions — skipping
Both front and rear dials for selecting aperture and shutter speed can “skip”: twiddling the dials three clicks to go from f/4 to f/5.6 might result in f/5 instead. This behavior developed over time, and seems to be slowly worsening. It’s very annoying because one has to verify exposure, rather than relying on click-click-click to go up or down one aperture or shutter speed. And some users report that the problem gets much worse.

As this was reported when the 645D came out nearly a year ago, it seems that Pentax still has not sorted out the mechanical issues.

07-10-2011, 04:12 AM   #5
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I bet they used the same dial as on the K-r. Mine and several others' cameras have had the same issue. It seems there's too much of some kind of grease in the dial/switch which causes the problem.

My camera developed the problem a few months after purchase and it was repaired under warranty. Some users had success "fixing" it by vigorously spinning the dial for a few minutes. This might be just a temporary fix though.

Here's more thorough diy fix for K-r by Predictor

Naturally opening the body voids your warranty.
07-10-2011, 11:48 AM   #6
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Faulty dial is not uncommon with any Pentax DSLRs. Have you 645D replaced or repaired. Don't DIY if still under warranty.

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