Originally posted by kenyee I thought F meant AF? What's a power zoom motor?
I need to apply for some bailout money... :-)
F* and FA* are both AF lenses.
The primary difference (other than cosmetic - white vs. silver, and some subtle shape differences) is the lack of a power zoom motor on the F* lens. The F* is an AF lens, but you zoom the lens' focal length manually, like most lenses in existence.
You can adjust the focal length using an electric motor via a rubberized ring (zoom ring) on the lens barrel in the FA* version. It's the same for the several other lenses Pentax made with the power zoom function.
Regards,
Marc