ETTR — just crank up the ISO? Part 2

SNR graphs are fine, but what does the preceding post mean with respect to image quality if I don’t push up the ISO to keep the histogram to the right? I wondered the same thing, so I did some testing. I took my usual noise test scene:

And I made a series of exposures with the D800E. The first one was with the ISO set to 3200, and the exposure set using ETTR, rendered in Lightroom, with no noise reduction and no sharpening. I cropped to the part of the scene I focused on, and made a 2x (nearest neighbor, no interpolation smoothing) copy:

Here is what you get if you use the same exposure at ISO 1600 and apply a +1EV exposure boost in Lightroom:

Same exposure at ISO 800 and apply a +2EV exposure boost in Lightroom:

Same exposure at ISO 400 and apply a +3EV exposure boost in Lightroom:

Same exposure at ISO 200 and apply a +4EV exposure boost in Lightroom:

Same exposure at ISO 100 and apply a +5EV exposure (all you can get) boost in Lightroom:

Not much to choose among these…