autofocus question

[chibitul smecher]

Hi, does Pentax use the ultrasound technology found in some Canon and 
Nikon lenses? I have a ZX-5n and I see that it uses a shaft (cannot 
find a better word) to achieve the auto-focus, IOW the motor is in the 
camera and there is a mechanical coupling between body and lens. This 
is not very quiet :(... I see there are a few other contact on the lens 
mount, so I wonder if other more expensive lenses got the ultrasound 
auto-focus motor. I only have a zoom 28-70 f/4 AL lens.

what about lenses where the front element does NOT rotate? using a 
polarizer filter with 28-70 f/4 is not fun. And BTW, while others seem 
to like the optical quality of this lens, I see very few that actually 
mention the poor mechanical build.