There is an excellent discussion of this topic in _The Making of 40 Photographs_ by Ansel Adams. In the text accompanying "Moonrise, Hernandez, NM" he recounts how after setting up his camera to capture this remarkable scene he couldn't find his spot meter, so he computed the exposure in his head using the luminance of the moon and the exposure formula. (At a shutter speed equal to the reciprocal of the luminance of the subject - 250 candles per square foot in the case of the moon, the correct aperture is equal to the square root of the film speed.)

He also talks about this in the text accompanying "Moon and Half Dome". The problem for the photographer is that the moon is of constant luminance while the illumination of the sky and scenery around it varies all over the map. The foreground of the moonrise photo was grossly underexposed as a result.