I was checking multiple reflections using a test scene of two mirrored
planes, one behind the camera and one in front. Put some spheres between
them, 100% red, green, blue, white and black. The planes are rotated
around the y to offset the reflections as seen from the camera viewpoint
so there are multiple reflections of this one group. A max_trace_level
of 15 used so there would be plenty enough to see.
Aside from the fact that the mirror pigments used (I made renders using
rgb 1, rgb 0.5, rgb 0, red, green, blue, yellow, magenta pigmented
mirrors) contribute to the mirrors colors even at reflection 1, which is
to be expected, an odd thing occurs concerning the black (pigment {rgb
0}) sphere. It only shows up in the first reflection, the mirror behind
it in this case. The other spheres remain as expected unless of course
they blend in with the equivalent colors of the 2 planes. The black
sphere is fine if the mirrors are white or gray (maybe black too but
then they aren't visible anyway) but they disappear if red, green, blue,
yellow or magenta pigment is used. I hadn't tried other shades of color
yet to check further since I just did a routine set of renders.
There seems no doubt this must be wrong. Since if the rgb 0 is showing
in one reflection yet none of the other multiples, and you would expect
it to not show at all if it is a case of "non-contributable color" or
some such.
I can't see how this effect has been overlooked before so it's probably
been encountered before and maybe ignored.
Using the Windows version 3.1 r1

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.htm
=Bob

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