It's probably possible to a point, but I sure wouldn't rely on it. Light is very difficult to judge because our eyes are constantly adjusting to various lighting, whether we're aware of it or not. Much of this adjusting is not done at a conscious level. I can usually rely on my eyes to tell bad light from good light, but beyond that I like to use a meter, although as you said, you need to understand how to use the thing. As long as I'm not dealing w/ overly reflected light off something bright and shiny, I get good results from finding a middle value, metering that, and using that as my exposure. That's w/ a hand held meter or a basic center weighted in-camera meter.
With my Nikon N8008s, I set the thing to spot meter, lock the exposure on the point of interest, and shazam...."correct" exposure. That $20 camera taught me that Sunny 16 is merely a ball park thing, at least with 35mm film, where incorrect exposure can cause big grain problems. One day I set it to spot and pointed it up into the sky w/ the sun behind me, then slowly lowered it. That particular day it changed nearly 3 stops by the time I got to the horizon! With a hand held meter I would have just aimed the meter vaguely upwards, got my reading, and wondered later why the sky was not properly exposed. The question was, WHICH part of the sky was important? I'd never thought of that, as I figured that it was all pretty much the same. Sometimes it is far from the same, and when I really looked at the sky closely that day I saw that it was deep blue toward the "top", then slowly changed to a lighter and lighter blue as my eyes headed downwards. Once my eyes got near the horizon there was a thin area that was nearly colorless. All these graduations gave different meter readings.
According to Ansel Adams, Weston owned a handheld meter. Adams commented that while he would use very involved methods to obtain exposure, Weston would walk around w/ his meter, seemingly pointing it at various random areas (probably looking for a middle value), then come up w/ exactly the same reading that Adams had arrived at by his complicated formulas.
Last edited by momus; 12-27-2013 at 08:29 PM. Click to view previous post history.