My take, ETTR is more about trying to gather as much data without blowing out highlights. More commonly phrased maximizing signal to noise ratio.
You have more signal to the right. Each photosite is collecting more electrons.
Just making up numbers, but if your noise is 10 electrons and you collect 20 electrons, the noise will be more obvious than if you collected 200 electrons. 2:1 ratio vs 20:1 ratio.
Edit:
Here is a write up that may help. Adding on to what I wrote and staying with the hypothetical numbers (actual pixels hold 10's of thousands of electrons), if you clip whites (oversaturate pixels) at 240 electrons/pixels, you ETTR so the brightest part of your scene is 200 electrons/pixel, that also allows you to take advantage of the dynamic range of the camera and your midtones are ~100 electrons/pixel and your darkest parts are hopefully well above your noise floor.
Canon used to have a higher noise floor, so as you adjusted in post or increased ISO you would see noise in the dark areas sooner. Starting ~2016 Canon improved their sensors and lowered their noise floor. So ETTR was more important pre-2016, but it is still an important concept and lets you gather as much data as possible for you to adjust in post-process and also lets you more fully take advantage of your camera's dynamic range.
Last edited:
Upvote
0
