I bought a Pentax *ist DS a couple of years ago from a camera shop. Discontinued leftover stock, but with a new camera warranty from Pentax. Turns out I needed the warranty. My guess is the camera was built with NO shim under the ground glass. Autofocus shots were fine, but when I tried manual focus things were wildly off - my testing indicated the ground glass was off by over a millimeter! Pentax fixed it no charge.