Yes, without any limitations. These lenses are auto-focus and will work in all exposure modes (P, Av, Tv, M, scene modes). The aperture ring on F and FA lenses must be set to "A" at all times. FA J lenses have no aperture ring.

[kshapero]

Yes, without any limitations. These lenses are auto-focus and will work in all exposure modes (P, Av, Tv, M, scene modes). The aperture ring on F and FA lenses must be set to "A" at all times. FA J lenses have no aperture ring.

Does this mean that the aperture ring will not work with the Pentax Digital SLR's?

[Adam]

Because the Pentax DSLR mounts lack the coupler that can tell how far the lens is stopped down, the aperture ring can't be moved away from "A" without losing auto metering. If you do decide to use the aperture ring, you'll have to manually get the camera to set the shutter speed and aperture as you do with K and M lenses.

[mummy]

Can someone please tell me why when I put my SMC Pentax-F 35-70mm f3.5-4.5 on my K10D, it not show the Aperture information? (F is blinking.. ..). When I put dial to Av mode, it show shutter speed at 30"?

[lpfonseca]

AFAIK there are 3 reasons for this to happen:
the aperture ring is not set to "A" and, as Adam said, the camera doesn't know the chosen setting;
there is some dirt in the contacts. In this case try cleaning them and try again;
there is something realy wrong with the lens and it might need a repair.