I'm working on an animation where I want both mist and dof combined with a rather dark world background. The main problem is my mist pass washes out my background, and the only solution I found was rendering the background in a separate pass. What happens then is I get a white border around all objects against the alpha background (I presume the border was always there, but becomes visible in alpha because it doesn't have the washed out background there). It even occurs to objects in the foreground where the mist pass shouldn't be effective. I've looked at tons of tutorials and forums, but can't seem to find a solution for this. It only affects objects out of focus, so it seems like the mist and the dof-defocus somehow have a conflict, where the blurry border around objects out of focus become white in the mistpass.
Does anyone have any experience with this? I'm pretty noob-y at blender and 3d in general, and though I've tried fooling around with nodes and stuff I'm not experienced enough to actually know what I'm doing. Any advice would be much appreciated!!