Archived posting to the Leica Users Group, 2000/08/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Dan I guess it is white because white has a very high reflectance of light (about 95%) and so provides the meter with a good amont of light to work with, and less denegrated light as the white does not absorb too much of that which is reflected from the subject. It is a dot so that the light is concentrated in a small area rather than dispersed. As for 13%, I too have seen this figure mentioned but, as I would presume with most people who use an M6, once I had done some grey card tests I only use my meter as a guide and often adjust the exposure to suit my needs. Simon Dan Honemann wrote: > Ok, here's a dumb question (so those of you who have low tolerance for dumb > questions can skip to the next msg now). The M6 TTL meters off of a white > dot on the shutter curtain. Why isn't the dot 18% grey? Does the meter > test light reflected off both the white dot and some of the black curtain so > that the composite represents grey? > > I'm assuming the meter works by comparing the reflected light through the > lens to the light reflected off the white dot. > > And why do we use 18% grey cards anyway when "scientific studies now > indicate that an average scene actually reflects 13% (not 18%) of the light > that falls on it" (Peter Burian, _National Geographic Photography Field > Guide_, p.137)? > > Curious Dan > >