Quote Originally Posted by markbarendt View Post
... but still, one must take a reading ...
The Exposure Formula is associated with the quote "Chance favors the prepared mind," so I take it to mean that knowing the formula and using it can help in a pinch when a meter fails or is unavailable.

Quote Originally Posted by Steve Smith View Post
... light level reading for industrial/business use such as installing office lighting. This formula could be used with one of those meters ....
No because these meters return incident candlepower measurement units and the formula is tied to reflected candlepower measurement units.

I don't assert that the four stop difference is a constant. But can anybody say? Maybe it is just that.