#### propmonkey

##### Well-Known Member
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??

#### zac850

##### Well-Known Member
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.

#### BNBSound

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

#### propmonkey

##### Well-Known Member
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.