> What about some image processing to detect the movement using the camera
> you already have?  (I guess it depends on the Field of View)..
>
> PC based frame grabbers are 'relatively' cheap now days, and the motion
> detection algorithm could be simple frame by frame comparison, execution
> times should not be too much of a constraint. Once you have determined the
> center of movement you could then zoom/autofocus and track..
>
> Maybe, some cross-hairs on the display.......!!
>
And what about stereoscopics?? I mean, maybe using two cameras, each one
rotating to center the subject, and mesuring the angular rotation of each
camera you could calculate the position of your moving subject.

Carlos Betancourt
CETI-UNET
Venezuela