And how different is 18% gray from 18% red?
I was thinking about the properties of light and spectrum to better understand the camera metering mode. 18% means approx 1 out of 5 photons will be reflected. If 5 photons of Red Green and Blue colours are incident on 18% gray and 18% red than gray will reflect 1 photon of each colour, so total 3 photons. At the same time red will reflect 1 red photon only or 3 red photons ? If it reflects only 1 photon than 18% gray might equals the 54% red properties. Please guide me so that I can better understand the metering. Metering modes , zones etc are clear so please dont bother about that. I tried my best to explain, hope you understand my question.