I was playing around with dispersion a little last night, great feature! I
especially like the sphere example posted on the MegaPov examples page, the
one where you can see some dispersion in the reflection of two box's with
high ambient:

http://users.skynet.be/smellenbergh/demopictures/disp2b.jpg

I got to wondering in what situations do you need to specify the spectrum of
a light source? In the above example no spectrum has been specified yet
dispersion can be clearly scene in the reflection of the two ambient boxes.
Is a spectrum only necessary if you want the caustics cast to contain
colours? I tried specifying a spectrum for the light in the sphere scene but
all I managed to do was wash out the scene or get a very harsh yellow tinted
light, it didn't seem to change the caustics or the dispersion. Do you need
objects with sharp corners to get good results from caustics and photons,
such as a diamond or prism? I also took a look at the macro in the prism
example for creating the spectrum. Now I'm not very good at writing, let
alone reading scripts, but from some of the experiments I did and from what
I can understand of the macro it seems to simply create a color_map which
with the specified number of entries that blends through the colors of the
rainbow, ROYGBIV. When I specified my own colour map using seven entries,
ROYGBIV, I got pretty much the same results as the macro. Is this really all
the macro does? The code makes it seem more complicated than that. Thanks
for listening to this babble:-)

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