Conventional wisdom is that for digital cameras it is best to expose so that the right side of the histogram is as far to the right as possible without blowing the highlights.
However; the raw converter I use allows exposure compensation of +/- 2 stops.
If I under expose does this mean I can bring out detail in the shadow areas or is this a false move. Having preached the conventional wisdom I was asked this question during a talk and I could not answer. Can anyone help.
Back to the beginning .
I think you're asking whether shadow detail can be brought out, in an underexposed image, by using the +/- exposure sliders in ACR.
I think the answer is both yes and no. The appearance
of the shadows can be lightened and more detail made visible by using the Exposure Compensation slider during conversion, just as it can with many other techniques in Photoshop, such as use of curves.
But as far as I know, there is no recovery
of shadow detail in the way that a minus adjustment of the EC slider can bring out highlight detail.
In order to get the most shadow detail in the RAW conversion it's necessary to have the 'shadows' and 'contrast' sliders at zero in order to minimise shadow clipping, and of course convert into 16 bit. Having done that, it doesn't make much difference if the EC slider is at +1 or -4. All the shadow detail that's there will be converted in both cases, but the conversion with a -4 setting will need to be lightened by other methods, such as use of curves or the shadow/highlight tool.
(Notice I wrote it doesn't make much
difference. It probably makes some
difference as a result of quantization issues, but nothing outside the realm of extreme pixel peeping, that I can see.)
Exposing to the right is basically just a technique of making the most of the dynamic range of your camera. If the scene you are shooting is of low contrast, it's not such a big deal. If the scene has a greater dynamic range than that of your camera, then it's very important to correctly expose to the right in order to minimise shadow noise. The alternatives would be exposure bracketing on a tripod and digitally blending the different exposures.