Archived posting to the Leica Users Group, 1999/12/23
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 8:30 AM -0800 12/23/99, Eric Welch wrote: >sometime around 12/23/99 4:56 AM, Frank Dernie at FrankDernie@compuserve.com >was heard to write: > >> >> ALL exposure meters are incident meters. Reflected light meters are simply >> incident meters with optical and/or electronic compensation built in such >> that when light reflected from an 18% grey subject is reflected back at >> them they give a reading the same as a simple incident meter at the subject >> would have given. thats all. > >Frank, you are flat wrong. I know physics just fine. Incident meter means >the light falls on the sensor directly from the light source. That IS THE >DEFINITION of incident meter. Reflective meter measures the light reflecting >off the subject, not just 18% grey subjects, as you inaccurately describe. > >The camera measures the light and reports back how to make that tone 18% >gray, it does not think that is 18 percent gray. It doesn't think at all! No >one, but someone who doesn't know what they are talking about, thinks a Zone >VIII tone is Zone V. > >etc. Eric, you're just going to have to go back and read Frank's post. I know you know how it's supposed to work, but Frank does too. Whether all meters are incident or reflective is a non-issue, as all meters do is measure and give readouts according to their calibrations. If you point them at the inside of a dome which transmits 18% of light and calibrate them accordingly, they are incident; if you point them at a subject and calibrate them as if they are pointing at an 18% (or whatever percentage seems reasonable), they are reflective. Past that, the photographer interprets, as he/she has experience, time, etc. * Henning J. Wulff /|\ Wulff Photography & Design /###\ mailto:henningw@archiphoto.com |[ ]| http://www.archiphoto.com