[Greg McKaskle]

If you want to measure this directly, there are a couple approaches. NI IMAQ has a calibration operation that uses a page of polka dots held in front of the camera to characterize the camera/lens distortions, field of view, etc.

A low-tech approach is to use a yard stick and a tape measure. Hold the yardstick in front of the camera, parallel to the camera sensor/lens. Move it back and forth until it goes from edge to edge. Use a tape measure to get the distance from the camera focal point to the yardstick. Some cameras have a small mark where the focal point is inside the camera, but you can use the distance to the lens or perhaps the center of the camera.

Now draw out a picture showing how the triangle 18" wide and distance away will give you the half-angle of your FOV.

Greg McKaskle