Alex Wuijts Posted October 19, 2007 Share Posted October 19, 2007 I can't quite seem to figure out how an incident light meter translates an amount of light to a suggested f-stop and how 18% reflection relates to this. Anyone here who can straighten this out for me? By the way, I don't mean 'how do you use an incident light meter?', I'm looking for a (simplistic) technical answer and can't find it anywhere on the internet. Very much appreciated, Alex Link to comment Share on other sites More sharing options...
Premium Member Kevin Zanit Posted October 19, 2007 Premium Member Share Posted October 19, 2007 It has nothing to do with reflected light. An incident reading simply tells you that to expose 'x' amount of light falling on the dome (incident light) at middle gray (18%), use 'y' f-stop. Link to comment Share on other sites More sharing options...
Alex Wuijts Posted October 19, 2007 Author Share Posted October 19, 2007 It has nothing to do with reflected light. An incident reading simply tells you that to expose 'x' amount of light falling on the dome (incident light) at middle gray (18%), use 'y' f-stop. Thanks for the quick answer, Kevin! Somehow the most simple things can be hard to grasp at times. Link to comment Share on other sites More sharing options...
Premium Member Walter Graff Posted October 20, 2007 Premium Member Share Posted October 20, 2007 Thanks for the quick answer, Kevin! Somehow the most simple things can be hard to grasp at times. Then of course there is the 18% grey myth. Link to comment Share on other sites More sharing options...
Premium Member Kevin Zanit Posted October 20, 2007 Premium Member Share Posted October 20, 2007 Ok, insert 12% gray where I said 18, but for the sake of not being confusing I am still going with what most of the world uses when referring to middle gray, 18% (in spite of the ANSI standard). If I remember correctly, gray cards are still printed in 18% gray. Link to comment Share on other sites More sharing options...
Premium Member Walter Graff Posted October 20, 2007 Premium Member Share Posted October 20, 2007 I've always enjoyed the real story that most are not familar with and thought I'd open the door to it. Here is an article I found that explains it well. http://www.bythom.com/graycards.htm Link to comment Share on other sites More sharing options...
Jonathan Bowerbank Posted October 20, 2007 Share Posted October 20, 2007 In that article, he said the issue was brought up in a Digital camera forum. Is it possible that DSLR meters and 35mm SLR meters are calibrated for different grey values? Could it be that DSLR's read 12% as middle grey to save you from overexposure, preserving more information in the digital image? Just puttin' these questions out there :) Link to comment Share on other sites More sharing options...
Alex Wuijts Posted October 27, 2007 Author Share Posted October 27, 2007 In that article, he said the issue was brought up in a Digital camera forum. Is it possible that DSLR meters and 35mm SLR meters are calibrated for different grey values? Could it be that DSLR's read 12% as middle grey to save you from overexposure, preserving more information in the digital image? Just puttin' these questions out there :) That would make sense, but my Sekonic 558 cine manual mentions a Calibration Constant (K) of 12.5 as well. My 18% world is collapsing before my eyes ;) Link to comment Share on other sites More sharing options...
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