And a lot of very smart people worked really hard to make it that way. "You push the button..."
Originally Posted by Bill Burk
BTW, there's more of that excerpt from Connelly's paper.
"Equally it should be noted that the geographic mean is a convenient measure for the sensitometric determination of film speed of reversal color films as will be shown later, and as such is of considerable importance. The use of the cadmium sulphide photo-resistive cell has made available much more electrical power than formerly and this, of course, appears as an immediate advantage; but some caution is necessary. If the greater power availability is used to reduce to a small value the area of the scene from which light is received, the measurement made is no longer of the average scene luminance which it has been stated above is that on which the photographic constant P, as defined later, is based. In this case, it would be necessary to know which part of the scene to select to obtain a measurement equal to the average, or alternatively, a measurement of either the maximum or the minimum luminance could be made, but then a different value of the constant P would have to be determined and used."
That last part is a little unsettling.
Bill, instead of eventually retyping the whole article, I've decided to upload a pdf version of it. Now you don't have to read it in installments.