I like the convenience of being able to tweak the renders with an exposure node without re-rendering. But obviously that's slow, so now I'm looking to find a way to roll those values back into the Maya V-Ray lights so I can do a multi-light draft in Nuke and then render one final in Maya with the tweaked values. The problem is that Exposure adjustments don't map directly to the linear V-Ray for Maya light values. If I find the zero light value in Nuke (lowering the exposure until the image is black) and map that to 0 value in Maya and finding the ratio of my adjustment, it still doesn't work since exposure stops or densities aren't producing linear increases/decreases like the V-Ray lights do.
Is there some simple math I can do to get the exposure value as a ratio (x:1)?