Originally posted by Adam The problem with this review is it recommends purchasing a relatively expensive tool, while it appears to be excellent, amounts to a surcharge on the purchase price of the K-r. I shouldn't have to spend this much money to get more accurate focus with a K-r using the kit DA L18-55mm lens.
So, I started digging further and found this excellent - and currently free (other than the cost of printing a sheet of paper) option:
PENTAX DSLRs: Front or Back Focusing Problems? Free test (Lens Alignment) charts for Pentax, Nikon, Canon, Sony, Olympus.
Yvon Bourque has an excellent step by step instruction. It actually took me longer to read his instructions than it took me to tweak my camera's auto-focus. His instructions specifically reference the K-5, but other than the menu position and reduced function set of the K-r, the instructions will be the same.
I used the kit 18-55 lens at roughly 28mm, Av with the maximum possible aperture (f/4.0), turned off Shake Reduction, set center spot focusing and placed the camera about a foot (30cm) from and level with the scale. I had adequate ambient light and didn't even bother with a tripod - I am sure I could get even better results if I had used a tripod, but I was at this point just experimenting to see if I understood the instructions. The target told me I was auto-focusing about 4mm to the front of my ideal focus point.
After a little playing, I figured out that the scale in the AF Fine Adjustment menu roughly corresponds to millimeters. and that you move the AF Fine Adjustment in the menu to the minus side for front focus elimination and to the plus side for back focus elimination. I currently have my camera's AF Fine Adjustment set to -4. Indeed, my test shots show better focus where I expected it to be.