Originally Posted by guilherme bauer 
I was wondering if the AF will work on K100D and others(older) DSLR. Sure, without the SDM.
Somebody knows anything about this?
From the Pentax Web-site.
When mounted on the PENTAX K10D digital SLR camera body, the focus mode is automatically switched to SDM-assisted autofocusing*. When mounted on other PENTAX digital SLR camera bodies, the conventional autofocus mode using a camera-mounted motor is selected.