In a word, yes. I have 10 or so auto focus lenses and the only one that is a digital lens is the kit lens. The rest are all older full frame film lenses and they work fine. You can just throw it in p mode (assuming it's auto focus) and fire away. Some of my lenses are probably much older than 5 years and work fine. I tried it out of A mode too. It did not show the aperture like it does in A mode but it still metered and exposed fine.
Edit, I tried an old manual focus A lens and set to A it gave apeture in the caera and exposed properly. ,out of A mode (with camera set to p), it didn,t display the aperture in the camera but still exposed fine. Here is the real kicker. I have a minolta lens that I riped the mount off and replaced it with an A mount from a broken lens, and it works in p mode with proper exposure. Pentax cameras were designed to be fully compatible with any pentax lens ever made. You can even use old screw mount pentax lenses with an official pentax adapter in full manual mode of course.
Last edited by ripit; 09-08-2011 at 05:29 PM.