Can you use the zoom function on a camera?
Using a fixed focal length throughout the acquisition process is recommended. To achieve a non-uniform projected pixel size, vary the distance to the subject. If you cannot avoid several focal length settings, e.g., if the distance to the subject is constrained, shoot several series of photographs, each with a fixed focal length. When using a zoom lens, make sure its position remains fixed over a series of photographs. You can use a piece of adhesive tape with a manual zoom lens to keep it in place. Wide-angle or fish-eye lens can be used if the suited camera model type is specified, ContextCapture can automatically estimate extreme lens distortion. Do not use digital zoom.