I've already seen the answer about the crop factor.
I'm writing a small software for motion tracking (from two cameras, videos) in 3D space and research. To do that, I need some information about cameras. Sensor size and pixel size relationship is one of them.
For some things, I need the sensor size, for other, pixel size, elsewhere, focal length. I need to understand if and what is the relationship between the two, and is it possible to calculate one or another.
At the moment I have a plain Canon A720 IS. The listed focal length is 5800, sensor size is 1/2,5'' (5.744 x 4.308 mm) and the pixel size i 3,1µm² (~1,76µm). How are these numbers related (mathematically)? Is there a way to calculate pixel size from the sensor/resolution/focal length/whathaveyou?
PS: After calibrating my camera with OpenCV (inaccurately, but close enough for debugging), I got a focal value of 633. This has to be multiplied by sensor size, so I end up with a value of 253,2. How is this related? This is nowhere near 5800µm, Canon-listed focal length, and 4620µm, for which I am getting the most accurate 3D positions.