Exposing to the right side of the Histogram...

In a recent workshop a question was asked regarding the best way expose in RAW format.  The question went something like this...   So, if I create two images, one shot at two stops over the metered value and one shot at two stops under the metered value the two stops under will be a better image?  The answer was "yes".  I don't entirely agree.  Ok, let me explain...


Over-exposing a digital file is one of the ten most deadly sins in digital photogrraphy.  Two stops over-exposure, even when in RAW format, is tricky to recover from (in jpeg, you very likely cooked the goose...nuked it.. like Linda Carter and LA in Termintaor II).  Highlight information will be all but gone and exposure and highlight recovery adjustments in post production will be a big waste of time...a kin to solving the national deficit...


While the image shot at two stops under-exposed likely gives the photography a better chance of recovering data in the shadows, and the highlights will have been preserved (sounds like a good deal), exposure adjustment to make the whites white again will most certainly be accompanied by a fair amount of digital noise as the shadows are pulled back up.

A properly balanced exposure will bring the highlight values towards the right side of the histogram without piling up and clipping on the right edge.  Once the whites hit the right side of the histogram detail information is lost.  (Turn on your Highlight indicator in the play back mode of your dSLR to show you if the whites are being clipped...the histogram can be deceiving.)  By pushing the exposure values as far as you can to the right without clipping, you give your self plenty of room to adjust both exposure and brightness, without concern about overdoing and exaggerating noise in the shadows. 

My answer to the original question..  Yes.. two stops under exposed is a better option, but neither extreme is a good choice.  Preserve the hightlights and gently pull out shadows in post...