Originally posted by sys3175 Please, do not post such misleading utterings. The cause for the problem is clear as stated by the original poster. There's no need to continue analyzing a solved problem, and you should really refrain from offering 'solutions' that have no relation to the problem at all, as this might only mislead others. Thank you.
I had two problems with my cameras that gave a similar exposure to yours Churro. I was told I had Aperture block which may be what you have with your camera where the magnetic device that operates your aperture malfunctions and requires replacing which is possibly what has been done to your camera. I later read that the K-5 and K-3 don't suffer from aperture block as this was fixed with later cameras.
one of my problems was in flash mode when certain lens defult to a shutter speed of 180 for the exposure settings and I was setting my shutter at 60 so I would take the photo and the image would be overexposed because I set to 60 instead of 180 shutter speed.
2nd problem eratic overexposure was caused because i was using x converters with AF and they were confusing the camera to thinking a 300mm lens was a 600mm and vise versa and the same with the x1.4 converter it was the worst. and to fix this I had to reset the camera to factory settings and start over I have not used an AF converter since and have not had the problem since and that took a month or two to work out. Before you say bullcrap the latest firmware upgrade for the k-5ii address the problem with pentax x 1.4 converters unfortunately I don't have the pentax converters. I am putting this here so if Churro has a problem again he has this to read and so does any other person. I also don't think this is a place for rudeness. I had a stroke I don't always explain myself properly.