This topic keeps coming up, in various forums. I agree with Andy: the correct exposure is the best exposure.(posted 9497 days ago)For merely "ok" results, people talk about B&W negative latitude. If you meter a grey card, you will get good detail in shadows about 2 stops below that reading, and highlights about 6 stops above. (Speaking very loosely, the film has more latitude to overexposure than underexposure.) The exact numbers depend on the film and development. On that basis, if your subject has a contrast range of 8 stops, AND you meter shadows and highlights, AND you calculate the mid-point, AND you set your camera to that reading, you will capture all the tones. Depending on your meter, you *might* get the same result by setting the meter 1 or 2 stops slower than your film's ISO, and taking an average reading.