An interesting article indeed, Mark,addressing one form of metering, but I have a question:
How and why is incident metering a precedent over more precise methods such as spot metering (including, but not limited to, duplex/averaged spot metering)?
Yes, it's the cut and thrust of the discussion, but incident should not be seen as the be-all and end-all of precision in metering. Because it is not. Many beginners are likely to be easily befuddled by contrasty scenes incident metered; I was one of them many years ago. For portraiture, incident is quick and fuss free, but in landscape, a much more critical and deliberated approach must be taken.
Incident metering, like reflective, assumes the scene (and its many luminance values) are average — which in a myriad cases it is not. True, it has a proven role in controlled studio-flash/strobe use where the precision of spot metering would add complexity and deliberation (something studios don't have now with digital, nor need nor can afford).
This is potentially haphazard with slide film where latitude does not allow grace for error and metering should be more critically employed. In high contrast scenes all critical luminance values from dark to light must be analysed individually because the scene is not average. This is the crux of the limitation. Even Uncle Adams would point this out.For slide film typically the readings would be taken, one pointed at the light source (to protect the highlights) and the other pointed at the camera (to protect the mid tones). This technique works in all situations but is most useful in high contrast situations where the subject is backlit significantly.
Visualisation of the tones of the overall scene is essential before relying on what a meter suggests. This is particulary critical using transparency film where detail is required in highlights and shadows, with the requisite midtone providing the balancing point. If you cannot get detail in highlight and shadow areas on transparency film, then you are working outside the parameters of the film, not the meter. Not all films are suitable for all conditions, and transparency film is a solid example.
I would strongly recommend people actively diversify with metering besides incident.