[Brooks]

Before we jump into real world exposure examples I think it might be useful to see exactly what the meter sees when we meter a tone and either accept the exposure given as a medium grey (N) or move that exposure up to a N+1 or N+2 etc. or down to an N-1, N-2, N-3, etc.

I've done a series of exposure samples this morning in the studio. Using a MF Digital Back, I photographed a white towel lit with a single hard continuous light so that the texture of the towel is easily seen.

I metered the towel with a spot meter and made exposures at N-4, N-3, N-2, N-1, N N+1, N+2, N+3 and N+4. The N exposure is the direct exposure indicated by the meter which produces a medium grey. Remember, THE TOWEL IS WHITE> The other exposures are either more or less exposure in increments of one stop.

The point of this exercise is to visualize the differences between these exposures and to find the correct exposure adjustment to render a textured highlight and shadow area. In the world of film a textured shadow would be usually be found at N-2 exposure and a textured highlight at N+2, possibly N+3. As it turns out this is also true with digital capture and this particular digital back at ISO 100. Your digital camera might be slightly different.

As you can see from these exposures highlight detail becomes blown out between N+2 and N+3 or about 2.5 stops over the meter reading. Shadow detail holds through N-2 and almost into N-3 which would be 2.5 stops below the meter reading.

The range of usable detail (Dynamic Range) for this chip is N-2, N-1, N, N+1, N+2 or 5 stops, perhaps just a bit more into the highlights at N+2.5

Here are the tonal patches for each of these values.....