quick question, im want to make a beam spread chart of the instruments we have. is this the correct way to find it? tan([beam spread angle]) x [height/distance] = the beam pool??

I don't believe so. I think you need half the beam spread angle, so that it is a right angle for the beam... but let me check. The program I use to do this math for me (LD calculator lite, it was free from somewhere, maybe ask google) says that the equation for beam width is: X= D * (2 * Tan (F/2)) Where D is the distance the light travels and F is the beam angle.

You can get Lumie Light to run on a Palm device, the Photometrics Guidebook is $13 invested very well too.

LD Calculator Lite is available http://www.paul-pelletier.com/LDCalculator/LDCalculatorPage.htm along with some other tools. Not only does it provide beam spread, but also power consumption, dmx channels, weight, and even a utility for how much truck space your cases will consume.

i have the calculator thing on this comp. when iwas trying to figure it out i was at school. i was thinking using half angle is the instrument was perpendiclur to the object or fall. in this case it would be at 45 degrees.