I recently purchased a Spy Gear Spy Trakr. $80 R/C Tank with video camera that displays on the remote. It's claim to fame is that it runs Linux and is user programmable. Hackaday.com did a few good write-ups on it //hackaday.com/2010/08/27/spy-video-trakr-first-impressions/
Unfortunately, Spy Gear has stopped supporting it and taking the source code with it. Darn.
In the meantime, it is still a fun little toy. I drove it around the apartment, tough to navigate on the small screen. Just for giggles, I thought I would swap out the lens with a wide angle lens. I had 3 other lenses from work: 3.6mm, 2.2mm, and 1.8mm. (The Spy Trakr lens looks to be 3.6mm).
These lenses are 12mmx0.5 thread, very common; the Spy Trakr lens is 9mmx0.5 thread, less common.
This is an image with the default lens
This is an image with the 1.8mm lens
A top view of the kitchen, er... test arena.
The green line is 1.8mm and red is the 3.6mm.
The wider view and increased "peripheral vision" make the Spy Trakr an order of magnitude easier to drive.
A couple of notes about the 1.8 mm lens. It was labeled as 180-degree field of view. Clearly not 180 degrees. The fine print is that on a 1/3" imager it yields a full 180-degrees, but on the Spy Trakr 1/4" imager, we get 90-degrees. Again, still better than the 45-degree Spy Trakr lens.
A problem though, the wider lens needs A LOT more light. Thus my images are bad outside of natural sunlight. D'oh. External LEDs will fix that.