What Does an Exposure change equal to in a camera f/stop

Bob Somrak wrote: A one stop exposure change in Lightroom Process Version 2012 is different than a one stop exposure change in Lightroom Process Version 2010. PV 2010 seems to move the WHOLE histogram but PV 2012 acts more like a midtone/exposure adaptive adjustment.

That is correct and due to PV2012's image adaptive controls. Highlight recovery is applied to the raw image file and Black point set even with all of the PV2012 Tone controls set to 0. Because of this raising (or lowering) the Exposure affects the midtones more than the Highlights and Shadows. However, raising or lowering the Exposure by a specific amount such as1.0 EV is the equivalent of raising the camera exposure by 1.0 EV (i.e. 1 F stop).

You can try this for yourself by shooting an image with correct exposure and a 2nd with -1.0 EV exposure compensation. Open them both in LR and apply a Basic panel +1.0 Exposure setting to the under-exposed image file. They should now look identical as long as there is no in-camera highlight clipping in the image.