I also tried to do gamma corrections, and the final render is aways darker than the exposure control preview, both are affected by the gamma, but the preview is brighter, and when a use the "no exposure control" the render and the preview is the same. But the problem is whith the vray exposure control, and its happens also in the default settings and to new files. I start to thing that is normal and nobody use the preview, Can anyone test this? Tell-me if it's happens whith you too. Do a new file, place a plan or any shape and choose vray adv 2.0 as the render, render this withought the exposure control, and after, choose the vray exposure control on the envirement tab, do a preview render. And render a production render again, see if the preview is more brighter. It's true or it's only happens to me?