Hi,
its possible to turn off applyAtmospherics on light objects? because when you have light in front of matte object with applyAtmospherics = false the light itself receive atmospherics and its visible even if its invisible in its properties.
This is a common issue but I was not able to find any solution except matte object in front of light with applyAtmospherics = false
See attachment and max file.
That’s caused by the VRayEnvironmentFog’s effect on the image’s alpha. Disabling the Matte plane’s “Apply Atmospherics” simply leaves out the portion, which overlaps the VRayLight (since lights don’t have such an option). We do have an improvement request logged for an “affect alpha” (internal bug-tracker id: VMAX-9793), however, it’s not on top of our to-do lists. I think it would be easier to use a Render Mask with the “Selected” mode, otherwise, you would have to remove the light in post (possibly with two renders).
Thanks Ill give it a try, but it looks promissing.
So I did a quick test and it doesnt work with vray scene objects so we cant use it 
any advice?
Well, that makes things a bit complicated since there are known issues with VRayScene and masking. What seems to work (it’s quite a sidewalk, I know) is separately rendering a mask (should be fast) by overriding the VRayScene’s shaders through the Override Snippet with a white Self-Illuminating material. A VRayMtlSelect for that shader should yield a b/w mask for the VRayScene node. The Snippet should look like this:
Node <*>{
material=whiteShader;
}
Create a new VRayMtl, set the Self Illumination to white and diffuse to black. Name it “whiteShader” and apply it to the VRayScene node. Use the VRayMtlSelect (with the shader chosen) as a mask in post.
Hmm this will make it too complicated. We have hunderts of renders and adding another layer its not good We stick with lights visible in fog and try to fix it in post