Carclo of course mentions
Originally Posted by rmteo
"It is important to note that it is
not possible to calculate
from the FWHM beam width how big the beam will look
to the human eye." (also from page 4 of the data sheet)
But, despite that, from experimenting I have decided to place the lights no more than 2 feet apart. Corresponds to the math pretty well.
Also, I did completely miss that the FWHM for the XR-E is 20 degrees! I looked only at the first LED listed, the White XR. I have seen reports that the XR-E has had a die change? From the EZ1000 die to the EZ900? ( http://www.candlepowerforums.com/vb/....php?p=2992875 )
How does that change things? I can see if you start with a slightly smaller point of light to begin with that your final beam of light would be slightly smaller, probably not very much at all. But it shouldn't change the angles used to figure the solution, should it?