K-m F setting

I have a Pentax K-m and whether I use my Pentax18-55mm, 50-200mm or my Sigma 10-20mm, 70-300mm and 150-500mm lenses the display screen recently only displays F4.0 regardless of the light conditions. Therefore some photos I took outside on a recent walk on a very sunny day were greatly over exposed (was using the 2 Pentax lenses at the time). How do I go about changing the F stop. I am not greatly technically ok with all the workings as this was a retirement gift which I have been using for a few years without any problems. Anyone any ideas or do I just go for a new camera as the K-m is now 12 years old and well used.

If this is too basic just ignore me... but have you checked what mode the camera is on? If it has been accidentally knocked to manual it won't change unless you change it.

Best wishes, Kris.

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Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
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HI Kris, yep first thing I checked and cannot seem to change it in Auto or Manual, like I said I am not overly tech savvy but thank you for your reply.

If set to Av then adjust the aperture with the rear wheel. Check that the lens is firmly attached and perhaps wipe the lens contacts and camera contacts with a soft dry cloth. Make sure any aperture ring is set to "A".

If that all fails, try a factory reset, found in the menus. If that fails, perhaps a firmware upgrade.

If all this fails then perhaps a quote for repair fro J Pye Ltd, the official Pentax repair house.

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Best regards, John

Hi John, thank you for your input I will run through your suggestions tomorrow and hopefully resolve the problem.

Best regards, Andy

Took the K-m to camera shop today where a very experienced owner gave it a good going over for 45 mins, outcome was the problem lies with the camera body receiving info from the lenses. By trying to wiggle the lens he managed to get readings from F4.0 to F8.0. Repair to mounting ring (if available) will be about £130 - £150 so will settle for a new body, just have to decide which model. Thanks for all your suggestions.