K200D does not suffer from the aperture block failure of the K-30/50/70 series. I have two K200Ds, and I recently got overexposed images with Rokinon manual focus lenses with the aperture ring locked in 'A.' Pentax A and FA lenses set this way do not overexpose locked in 'A.' If you're using lenses with aperture rings, set the lens at a specific aperture (say f5.6) and try the first shot that way.