I have a scene that involves a lot of smoke (burning oil well style) and several lights, including mesh and sky. The smoke is extremely noisy, even at 4,000+ samples. I can remove a fair amount in post processing with the compositor and photoshop, but the more I can remove in the initial render, the less i have to damage the sharpness of the image with post processing removal.
So, what can I do to get the noise down in the initial render? Do any settings other than samples have a good effect? Keep in mind that having the light properly glow through the smoke is an important part of the scene, so I don’t want to hammer the quality too badly.
I’m not great with smoke but here’s a few things that helped clean it up some in cycles.
In render settings, volume sampling, try reducing max steps from 1024 to 64, 32, 16 untill you can actually see a degradtion in quality.
Increase step size, until noticable issues.
That will drastically decrease sample times allowing for much faster and higher samples.
Filter glossy to 1-2
clamp indirect 1
A few other things, post if any of that helped. Good luck.
Make sure your number of smoke bounces isn’t higher than 1 or 2. You may even be able to get an acceptable result with 0. Any higher and you’ll be waiting hours or days for your render to clear up.