Quote -  

The left render shows the setup: no lights, only the ambient on the ball. The middle render is with the ball invisible to the camera. Nice, soft light, ready for adding a hologram, or a fairy, or a magic energy sphere (either in post or directly in the render). The third render is exactly the same except I added a mirror behind the hand and oops, there's the ball. And there's no way to eliminate that ball showing up in reflections.

     Keith gives a clear and concise explanation of the problem.  Yes, that phenomenon doth vex me. :glare:  The tick box marked visible in camera can be unchecked, but what it actually means is not visible on the first passage of a ray, but visible in any and all subsequent ray passages. :tt2:

     If we could get an additional tick box which would make a mesh remain "not visible in camera" that would solve the problem.  But the mesh light designation with adjustable IDL gain would be a more elegant solution.

     Of course, adding both features would give flexibility.

     Moriador is also correct regarding there having been an issue with proper point light attenuation;  that in itself I can usually adjust for, but what about projects like Xanadu with wraparound neon tubing, or the big Lothlorien trees with a hundred lanterns?  For these situations, point lights become untenable, but mesh lights are an easy and natural solution.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5