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06-22-2013, 04:18 AM   #1

Pentax KM aperture problem


I have a Pentax Km which suddenly stopped working - would not auto focus, pressing shutter release has no effect.

If I go to the custom menu 3, option 19, 'Using Aperture ring' and change this option from 1 'Prohibited' to option 2 'Permitted', then I the camera starts to work again - auto focus works, pressing shutter release works and takes a photo. However, aperture setting does not seem to change e.g. through the viewfinder shows f8.0, on screen shows f4.5.

The same thing happens with both my 50-200 and 18-55 lenses.

Any advice please - is it worth repairing?

06-22-2013, 03:34 PM   #2

Join Date: Mar 2010
Location: Frankfurt am Main
Posts: 1,094
If a DSLR behaves strange, there are 4 things you should check before thinking about repair/service:

1) Clean the electric contacts of the bajonet mount.
2) Check the batteries and make sure, ALL of them are at the same (full) level.
3) If you use rechargable ones, try to find out whether the loading device ist still ok.
4) Turn the mode wheel several times all around, it may clean contacts from possible oxidation.
5) Reset the body to factory settings (prior to that, you should perhaps make notes about the settings, to regain them later on).

All points I mentioned are known to sometimes cause problems in areas which, at the first glance, don't seem to have any relevance to your problems.

Can't tell whether a repair would make sense - on German eBay the K-m (K2000) body usually is won by bids of €130-€190.
06-28-2013, 11:32 AM   #3
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Join Date: Jun 2013
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Thanks for the reply RKKS08.

I have tried the things that you suggested but unfortunately they have not made any difference.

Do you have any other suggestions?

Thanks again in any event.
06-28-2013, 05:30 PM   #4
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First thing: make sure the lens aperture ring (if it has one) is firmly in the A position. The symptoms are that the camera is not connected to the lens electronically with the contacts. All old manual lenses work as described.

You can use the camera and lens in the meantime if you set the camera to M (manual) mode and use the green button (might be the AE/L) to set the exposure. You will hear the camera stop down as it sets the shutter speed to match the aperture you physically set on the lens.

Use a micro fibre cloth slightly dampened with alcohol and clean all the contacts on both the lens and the camera body. Also, check that the contacts are not stuck down. Some use a pencil eraser to "erase" the dirt off the contacts.

07-01-2013, 02:06 PM   #5

Join Date: Mar 2010
Location: Frankfurt am Main
Posts: 1,094
Of course the suggestions of Canada_Rockies should be considered.

However, it seems both your lenses don't offer an aperture ring. If body and lens were ok, enabling of the aperture ring shouldn't make any difference. If it starts behaving different with YOUR lenses after toggeling the option, something is wrong.

M mode with Green Button will only work if the body can find out there is a lens connected, but is unable to get any additional information. This means several of the contacts (or all?, I am not sure) must be shortcutted against the bajonet mount. If your lenses have a plastic bajonet (DAL versions), this should not work anyway (if the body was ok).

M mode with Green Button should only work if the camera also asks you for the focal length of the lens after switching on. If SR is switched on and it doesn't ask, with a K-m stop down metering in M mode will not work.

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