Mist Pass differences between Render Layer and Viewer For some reason there's a difference between the render layer's Mist Pass itself and the pass seen through the Viewer Node at least in Cycles.



I need an explanation to this, because I've experienced this changing into an animation too.
Passing it through the viewer like that causes it to be treated an output color instead of a data pass, so Blender starts gamma correcting it. When you view a pass directly, it is not corrected and you just see the raw data. You can verify this by checking values in a particular region on the raw pass, and comparing them to linear values shown on the viewer (not the ones labeled "CM"). They'll be the same.