|Salzburg - August 2011|
The craft of traditional black-and-white photography consists of three stages: exposure, development, and printing. Each has its niceties and techniques with which specific "looks" or other effects can be created. With digital black and white, the latter two phases, "developing the negative" and "printing" happen in post-processing. However, there is a digital analogy to this three-step process.
|Stachus, Munich - August 2011|
The objective of correct exposure in film black and white photography is to capture as much of the dynamic range of the scene as possible, with as much contrast in the critical midtones as feasible. The same applies for digital, only the rules are reversed.
|Reading experience under the open sky|
The big difference between digital and "silver" black and white is in dynamic range. Black and white film has so much latitude that it's not much of an exaggeration to say that no matter how you expose it, you'll get a usable picture. Moreover, black-and-white particularly likes overexposure: in fact, it's common practice to shoot B/W film at one stop below its rated sensitivity – ISO 400 film at ISO 200, and so on. With digital, it's the other way around: to get a good picture, you need to be pretty careful with the exposure, especially at higher sensitivities, and especially careful not to overexpose -- otherwise you'll lose the highlights.
|Salzburg Cathedral - August 2011|
Digital cameras are designed to mimic color slide in their response. In fact, blown highlights are less distracting in color photography, since the color adds another dimension to the picture: the blown-out bits aren't necessarily the ones that stick out. Black and white lives and dies on tonality, and blown-out bits are much nastier... unless you work them into the look of the picture, that is. Moreover, "digital highlights" even below the blow-out point are often flattish, lacking in tonal detail.
There is another important difference about black and white and color: grain or noise. Noise generally looks pretty bad in color photography, while in black and white it can actually add interest to it -- so much that at times it might even be advisable to add noise to the final product.
Be as it may, while with digital color photography blown highlights are an issue to be managed, with black and white, they must be fought. In fact, the main issue while behind the camera becomes to make the most of the dynamic range there is. There are a number of approaches to this.