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08-22-2012, 07:36 AM   #1
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K-x aperture problem

I've been using a K-x for about 2 1/2 years and suddenly, last week, i turned it on and it doesn't let me change the aperture.

It does changes in the viewfinder, but not in the screen and when i take the picture it uses the value that showns in the screen (wide open) and the image is overexposed (as many stops as the diference wide open-value of aperture in viewfinder)

I tried cleaning the contacts and upgrading the firmware...

hope someone knows anything about this.

08-22-2012, 07:50 AM   #2
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Tried different lens?
08-22-2012, 08:58 AM   #3
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Also, what does the EXIF data say?
08-22-2012, 04:19 PM   #4
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tried different lenses: 18-55, 55-300, sigma 400 5.6, 10-20, f50 1.7 and same results...

exif data says wide open aperture.

thanks

08-22-2012, 05:06 PM   #5
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Have you tried both AV and the green mode?
08-22-2012, 06:06 PM   #6
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i've tryied all the modes, same result...

the only way to get a desired aperture is by using an aperture ring lens at manual mode.
08-22-2012, 09:25 PM   #7
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QuoteOriginally posted by Tanzer Quote
Also, what does the EXIF data say?
This is a good suggestion to see if it reading the lens you have mounted is correct.If so you might try changing the setting allowing aperture ring.
Hope you don't have a problem with the leaver that changes aperture.
08-23-2012, 09:29 AM   #8
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We just sent my son's KX for repair for the same reason. Additional problem was the camera always started up in Av mode, regardless where the control was set. If you go to the custom menu, C 22 and set it to allow manual aperture ring operation, the camera will work. The camera is not sensing the presence of an auto aperture lens, and therefore doesn't operate if C22 is set to "prohibited". We believe it to be a broken contact connection in the mounting ring on the camera.

08-23-2012, 09:55 AM   #9
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QuoteOriginally posted by JPBigony Quote
We just sent my son's KX for repair for the same reason. Additional problem was the camera always started up in Av mode, regardless where the control was set. If you go to the custom menu, C 22 and set it to allow manual aperture ring operation, the camera will work. The camera is not sensing the presence of an auto aperture lens, and therefore doesn't operate if C22 is set to "prohibited". We believe it to be a broken contact connection in the mounting ring on the camera.
Thanks!!

I left it on "allow manual aperture ring operation" since day one, so I could always take a picture but it was at wide open aperture and overexposed at some specific conditions.

please, let me know how your experience with the repair goes.
10-01-2012, 09:46 AM   #10
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Received the Kx back from Pentax repair (approximately 1 month). Repair form states "Repaired Mount Encoder Contact Circuit". The camera now works as new. I am glad I purchased an extended warranty when I bought the camera (2 additional years).
10-02-2012, 05:00 AM   #11
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could you please provide some more info on the repair? did they change the whole circuit block for aperture or did they managed to fix it? Or was it just a contact fault inside the mount? I believe i have the same issue with a k20d, from what i talked with the guys on the forum...
thanks.
10-02-2012, 05:35 AM   #12
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QuoteOriginally posted by vicentesagredo Quote
I've been using a K-x for about 2 1/2
Mine is also about that age, how many shutter actuations did your K-x have when trouble started?
10-02-2012, 06:14 AM   #13
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mine has around 14k... but i don't think the issues has to do with the shutter, since the camera can't control the aperture when the lens is on A mode, or am i wrong?
10-02-2012, 06:21 AM   #14
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QuoteOriginally posted by JPBigony Quote
Received the Kx back from Pentax repair (approximately 1 month). Repair form states "Repaired Mount Encoder Contact Circuit". The camera now works as new. I am glad I purchased an extended warranty when I bought the camera (2 additional years).
Thanks, now i know it can be repaired. I'll try to find some repair center closer, the closest one seems to be at around 4.000 milles LOL

QuoteOriginally posted by altopiet Quote
Mine is also about that age, how many shutter actuations did your K-x have when trouble started?
it only has about 20.000
10-02-2012, 06:33 AM   #15
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"mine has around 14k... but i don't think the issues has to do with the shutter, since the camera can't control the aperture when the lens is on A mode, or am i wrong?"

You're correct, actually just asked as a matter of interest, should have asked how often the aperture have been changed using the control wheel... or something that might have an influence on the aperture. I shoot mostly in AV and usually at f7.1, and don't use the camera controls to change that very often. I have about 32000 actuations on mine. If you use a lens with an "A" setting, the camera controls the aperture, to my knowledge.
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