Thanks Gary, I did read Mr DiNatale's article but as best as I can tell from re-reading it briefly, he does not really answer the question of what to DO with this "optimally exposed" image, e.g. the best way to process it....
Initially it seemed to me that just moving the exposure slider in LR to the left, e.g. reducing the exposure of an "overexposed" image would be the same as making an exposure at the reduced amount but it appears that is not the case. Thanks for your comments, they are appreciated.
Hi Eric-
If, in fact, the exposure slider in your raw processing software operated in a strictly linear fashion, then this would indeed be the case. The advantage of the "overexposed" image (I dislike the term because it is only overexposed based on the camera meter's reading.) is that, after moving the exposure slider in LR to the left, one can then boost the shadows without accentuating noise.
However the exposure slider in Adobe, Process 2012 (ACR and LR) does not operate in a linear fashion. Thus reducing the exposure with this slider will result in compressing the tonal range of midtones and below while expanding the tonal range above the midtones. This means that you will have to apply some boost to the shadows
if you need to increase detail in that area. Other raw converter software may differ; I don't know.
The general message of Mr. DiNatali's article (and most other ETTR discussions) is that, if you rely on your camera's meter to set exposure, you have significantly more headroom to increase exposure before you risk blowing out the highlights. (A story so old it has grown whiskers while we wait for the camera makers to give us on-camera access to the raw data.) This leads to his concept of an "Optimum Exposure", which will be somewhere between +0.6 and 2.0 EV above the camera meter's recommendation.
If you are really interested in how this behavior relates to your own camera I strongly recommend the article:
http://www.rawdigger.com/howtouse/calibrate-exposure-meter-to-improve-dynamic-rangeand carry out the procedure described therein. It requires you purchase a copy of RawDigger software (very inexpensive). I have recently carried out this test with my D800; it is easy to do and to understand.
After examining my results of this test and later reading Mr. Dinatale's article, I believe this article contains at least one serious flaw. "
Method #2, Using in camera multizone metering". He recommends using the raw conversion software's (LR or ACR) highlight clipping indicator to determine the Optimum Exposure. This would be the highest exposure at which no (or very minor or specular) highlight clipping occurs. (Choosing from a series of 3 bracketed shots at 0.6 EV intervals.)
The highlight clipping indicator in LR & ACR will be very dependent on which Process is used. In my examination, using Process 2012, highlight clipping does not becomes apparent until one exceeds +3.7 EV (above camera meter). With Process 2010 highlight clipping becomes pronounced at +2.7 EV. Using other raw conversion software one might well expect still different values. Using the RawDigger analysis I find that (with my D800) there is a headroom of +3.0 EV above the (spotmetered) brightest highlight. YMMV.
Bottom line, to answer your question: " what to DO with this "optimally exposed" image, e.g. the best way to process it."
It's really simple: process it the same as you would any other image, by eye-ball!. Begin by backing off the exposure slider until it looks right, and go from there. Your only advantage is that, if you need to boost the shadows to extract more detail, you can do so without risking increased noise.