ETTR — just crank up the ISO? Part 12

I went through yesterday’s D4 testing, this time with the D800E.

First, a check to make sure there are no serious self-heating problems. Exposure was 1/4 second at ISO 6400 at one frame per second. Subject was the back of the lens cap:

And the standard deviation (noise of the noise floor) looked like this:

It’s interesting that the red and blue channels bounce around so much more than the green channel.

I looked at the noise floor versus ISO setting:

And also the standard deviation of the noise floor:

And finally, the Zone IV (actually about Zone III.6 (or it it Zone III.IV?) for the green channel, and less for he red and blue) SNR versus ISO setting:

And the above curves with the half-stop/stop slope subtracted out:

My conclusions? If you’re shooting raw, and unless there are special circumstances (more on those in a future post), you’re probably OK putting gaffer tape over the ISO button on your D800E. If you do decide to crank up the ISO, stop at 3200.