[user]shiben[/user] and I are saying the same thing. The difference is he is willing to compromise (lower) the angle of elevation to accommodate the photometrics of the frontlight (only) fixtures. Without a careful study and more information, I'm not sure I'd do that. But maybe I would. Lighting is all about knowing when/where to compromise and when/where to stand one's ground. ("No, Mr. Artist's Representative, I WILL NOT randomly fire all the strobes during the ballad." "Oh, you're threatening my paycheck? Well then, here you go! <strobe> <flash> <bang> <bang>. What do I care?--I'm only the lighting guy." )
You are correct. In a perfect world with perfect lights, beam angle and field angle would be exactly the same. But since it's not, using the calculations for the smaller of the two, beam angle, gives you some wiggle room, and ERS have shutters don't they? Easier to make the pool smaller than larger, exactly what [USER]misterd[/USER] is currently confronted with....To get a beam size, do the same thing, but make a cone with the pointy bit the angle of the instrument (beam angle is the one you want, I believe, correct if wrong), and line the axis of the cone on the throw distance. ...
[USER]misterd[/USER], tell us the model number of your fixtures, and I'll post the cut sheet which contains all this information....Often, manufacturers will give data on the photometrics of their instruments either on the Web or in print form somewhere. ...
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