This is either a bug or I am completely misunderstanding the opacity option in the light material.
I would expect the opacity to determine which part of the emission texture is visible and illuminating, but obviously it does not work that way.
My original plan was to use a flame texture für lighting a portion of the scene and having an alpha texture cut out the black part.
It works with a standard material and self-illumination, but it is pretty noisy, of course, so I'd prefer the Light material.
Any ideas?
CU
Michael