1. Power Zoom
The zoom is motorized. The motor allows for three zooming speeds at a small twist of the zoom ring. The lens can also be zoomed manually by turning the zoom ring, a necessity with cameras that lack support for power zoom.
2. Lens Retraction
The zoom lens retracts to its shortest physical size when powered off.
3. Zoom Clip Mode
You can preset a focal length and you can then recall that focal length by pressing the zoom setting button on the lens.
4. Image Size Tracking Mode
You compose using the viewfinder so that an object (e.g. a child) fills the frame, say (a full body shot for example). When the object moves towards you or away from you the camera will zoom the lens so that the object maintains its image size.
5. Zoom Effect Mode
The lens will automatically zoom from wide angle to tele during exposure thus creating a special effect where the subject diffuses radially outward.
Which Camera Bodies Support Power Zoom?
All five modes are supported by the PZ series of film bodies.
High end DSLRs (K10D, K20D, K-7, K-5 series, K-3) and certain film bodies like the MZ-5, MZ-5N, ZX-5 and ZX-5N only support the first two modes mentioned above (the K10D requites firmware 1.30 or higher for Power Zoom support).
The remaining Pentax DSLRs do not support Power Zoom at all: *istD series, K100D, K100D Super, K110D, K200D, K-m/K2000, K-x, K-r, K-50, K-30, K-01, K-S1.