Q) Digital cameras have a linear response to light. Adobe, in its tutorials on Camera Raw, suggests “exposing to the right” in order to maximize the midtones and shadow information recorded by the camera. What's the best practice you suggest, and how does one go about determining the right “exposure” when using Raw capture?
A) Photographers have always been advised to expose for the shadows and process for the highlights, even back in the film days. Some of this holds true in digital capture as well—with some reservations. We now have information on the back of the camera, the histogram, that tells us where the tonal values fall relative to the exposure used.
Always be aware of the brightest and darkest tones. If they fall off the histogram (the extreme right and extreme left of the graph), they're “clipped” and become pure white and pure black. You won't be able to “process” them later in your image-editing program (such as Photoshop). To put it simply, if the histogram has tones cut off against the right side, there will be no detail in the bright areas, and tones clipped from the left side means there's no detail in the darks, whether you plan to print or to project the final image.
At the same time that you're exposing to move the tones in the histogram to the “right” as much as you dare, consider the tonal values of the subject and look for the histogram to reflect those values. To expose a black gorilla as far to the right on the histogram as possible will render it gray, and you'd have to modify the image file to bring it back to a normal rendition for a black gorilla. So take the advice of exposing to the “right,” but keep the tones in the scene in mind and watch those ends of the histogram at all times.