The problem you see is about a rotated viewfinder element, optically, and/or a rotated CCD sensor which is/are misaligned at the factory when they were installed.
You can check for the sensor alignment first. First you should look at if the central AF/Spot meter bracket is right in the centre. If it is so, face a mirror, put the camera on a tripod with a level indicator (mercury or any colored fluid), view thro the finder, see that you camera is in the dead centre of the bracket, then optically you have aligned the optical axis so that no any inclined lines shall be seen owing to tilting or shifted to the left or the right.
Surrounding the mirror, there should be some rectangular or square lines which are absolutely perpendicular to each other so that you can see if the vertical or horizontal lines are "rotated" in this case.
If the horizontal are "rotated" when you see thro the finder but that the level indicator on the tripod (or something that mounted on the hotshoe is also fine for this test), then you finder is misaligned. If the finder image is okay as seen but the final image is rotated, then the CCD is rotated.
In both or either case, only Pentax may help you, but I bet the re-adjustment for both will be a difficult task at the local service centre as it should be done in the production line, before everything are assembled together.
Hope this helps.
p.s. My experience is that my *ist D bodies had the most obvious "rotation" while my *ist DS ones have a little bit. My K100D, surprisingly, is perfect, so that I now get very good levelled pics as its finder is very accurate!
Originally posted by friolator I have a K10D and have noticed that no matter how carefully i compose the image using the edges of the viewfinder as a reference, my resulting photos come out slightly rotated. Curiously, the same rotation percentage in Lightroom is all it takes to correct for this. At first I thought maybe i was slightly rotating the camera when pressing the shutter, since the right side of the photo always comes out a little lower than the left, but i've confirmed that it's not me by placing the camera on a flat, level surface, making sure my vertical and horizontal lines in the photo were correct and then taking a photo that's slight off kilter.
So, could this be something in the viewfinder? it seems highly unlikely to me that the sensor is askew, but i could imagine a viewfinder problem. I don't think it's the focusing screen, because i'm using the edges of the viewfinder frame and not the etched lines in the screen itself as my reference.
any thoughts?