bruno021, you said "I create alpha planes in PS and place them in my scene, so they look like patches of fog, like volumetric spheres, but the render time is a lot quicker. To creates the planes in Photoshop, use the free "cumulus" plug in from Flaming Pear." I would like to try this. Is it simply a matter of taking the airbrush and painting black clouds on a white background in Photoshop, then making an alpha mask of it ? Could you explain how one could go about making alpha planes in Photoshop for fog? I am interested in this so it might cut down on render times and I think it might look better than using a volumetric material and a sphere. Thanks