- =ATAN(Length Of Image/2/Focal length)*180/PI()*2
Clearly the dimensions need to be in mm. Of course the angle of view of the height can also be calculated by using the same equation but replacing the length measurement for the height measurement.
With the range of crop factors currently in use it can be quite disorientating trying to get a grip on just what a lens can achieve and so this will assist.
Cheers,