Quote Originally Posted by wiltw View Post
That is a nice generalization. However, to illustrate the amount of error, I just measured at the back of my house in bright sunlight and while Sunny 16 held true (ISO 100, 1/100 f/16) in the sun; at the front of my house and in the shade shielded by the house, I measured between -4.4EV and -5.7EV difference in light depending upon exactly where I took the reading of the gray card...f/5.6 would have been wrong. Sunny 16 derivative says -4EV for open shade (f/4), but even that would be in error compared to what I measured.
So shooting trannies I might have a problem but my negatives are very reliable at those settings.

Actually the numbers I put up are typical of actual incident meter reading in those situations.

I actually go to f4 for fully back lit subjects.

There is also a fair dose of bias applied in any exposure decision.

My big point is simply that with a bit of practice and judgement good exposures can be made quickly in full manual.