Grabbed this out of my files... http://homepage.mac.com/godders/AoV/
It doesn't show quite as dramatic a change in 'crop factor' as I alluded to, but then I'm not entirely sure what algorithm Rui is using to calculate field of view. Another calculator I've seen shows a larger discrepancy.
Godfrey On Jul 17, 2005, at 6:50 AM, Godfrey DiGiorgi wrote:
Perhaps you're seeing evidence of the fact that the "1.5x crop factor" is a simple *linear* approximation of the field of view difference. Field of View in fact does not change linearly with respect to focal length on a format, a true factor for an 18mm lens is probably a little closer to 1.4-1.3x to give a 100% accurate calculation. I'll make up a chart demonstrating this for you in a little bit.
