"Did you have a look at the GoPro HD camera? Soo light if you remove the waterproof casing (and even the plastic case of the camera). I think that's what I'll use in my UAV from now on. For 3D, you could use 2 of them, but I think I'd rather use 2…"
"I used a CMUCam2 (http://www.cs.cmu.edu/~cmucam/) on a UAV project 3-4 years ago to do a similar task. It's relatively expensive (200-300$), but it's really fast and efficient to track color objects or movement and doesn't need to do the processing…"