Archived posting to the Leica Users Group, 1997/07/14
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Date: Mon, 14 Jul 97 20:15:04 +0200 From: Erwin Puts <imxputs@knoware.nl> Now the assumtion behind the 18% is the idea that the average distribution of light and dark tones in a scene is equal to 18% reflectance of the incident light... In reality the distribution of light and dark scenes follows the standard statistical Bell curve. If you adopt this in the exposure calculations, then the average scene has a reflectance value of 13%, which is more realistic... Hello Erwin, I found these sentences hard to understand, and was wondering if you could explain this further. Are you saying that, while the ensemble average reflectance over all scenes that people might be expected to photograph is 18%, the mode (the reflectance value that the largest number of scenes has) is in fact 13%? But this is not characteristic of a "bell" curve, for which mode and mean are the same.