Excepting hand-held, available-light aficionados, under-exposure is something we tend to avoid like the plague. But overexposure? No problem. All black-and-white camera films handle overexposure with ease. Or do they? It depends on the shape of a film’s characteristic curve.
Many photographers, especially fine-art photographers, routinely overexpose film relative to its ISO speed rating. Typically, this is done to capture additional shadow detail in the negative, affording the opportunity to include it in the final print, or not, once it is time to make that print. Two films may furnish rather similar tone reproduction when both are exposed “normally,” based on their ISO speeds. But overexpose both, and even with careful attention to processing, tonal differences can become profound.
Our March/April 2005 column discussed differences in negative appearance that result from two different film-curve shapes when both are “normally” exposed at the standard ISO speed. Here we will overexpose both films by two stops.