Heh, +1 on the shutter priority thing, it does take getting used to.
One of my brain farts was to assume the camera knew when a flash was on it. WRONG! I got a nice set of examples of what happens when the shutter speed is > than the flash sync speed
Another brain fart was mis-interpreting K/A on a Vivitar 200mm as Pentax KA. Of course the EE on the aperture ring should have raised a flag. But $20 later I had it at home, and discovered it was a Konica mount. But it mounted on the K100D, and metered, and focused to about 20 feet. Here is a sample; in a pinch one can use the Hexanons on a Pentax, but they'll behave like they have extension tubes on them