Quote Originally Posted by wiltw View Post
An incident meter tells us the exposure to use for an average scene's range of tones
Well there's an urban myth.

It takes two readings, to tell us the range regardless of meter type. A single reading from an incident meter tells us nothing more than a single reading of a spot meter, they both only measure single points, not a range. The only difference is that with a reflective meter we have to judge the reflectivity offset, say 1-Stop for Bill's hand.

Neither meter knows anything about the films range unless we tell it, and only a select few meters will take that input and spit out range info; most of us have do the math to find the SBR with either type of meter.

See post 4. My suggestion there is an adaptation of a technique called duplexing. (See Dunn & Wakefield's Exposure Manual) Duplexing was specifically designed for finding the best exposure compromise for slide film.

BTZS uses a variation of this duplexing technique with either incident meters or spot meters, at the users discretion, to accomplish what Adams did with with his Zone System and spot metering.