I do lighting design for my school, and am working on recommendations for LED upgrades. I have been looking at the Fuze Par Z120 IP, and need to calculate the diameter of light one fixture would produce at a certain zoom level given its height off the ground (this way I know how many lights my school would need to wash the entire stage). I looked at the Photometric Data for that fixture, and would like some explanation as to what the values mean. More specifically, what do the values in the first section of the Min/Max Zoom Charts represent (with lengths as the column titles and beam diameter / field diameter as the row titles)? What are beam diameter and field diameter?
Thanks to anyone who can help explain this!