You have your scene done, and you work on your light setup.
- You want the light emiting objects to be reflected on your surface.
- And your composition looks at its best when the lamp is in camera view, but you dont want to show the light emittors themselves as white surfaces.
So you have this
but would like this
Then hide the lights by this
You could also play a bit with this, there is also an Invert node, which you could put in between the mix shader and one of the other lightpath info pins.Another tip I used a quick cycles render here, but if your object is reflecting like glossy or other ways, then on high res renders you might find back these squares as reflected objects, well in general if you see a square, you see a corner and will try to estimate shape size and distance; its a human thing we do that automatic But if you use a sphere instead we do this less, as a part of a round shape doesnt reveal that much (thats from my photography school) so square lights often reflect as unwanted squares on glossy surfaces, in general circles or ring lights look better.