I'm confused. In the DSLR Guide's chapter on ISO noise, I originally stated that it was optimal to shoot at ISOs divisible by 160, because the camera's noise levels were lowest. Then I was told that this came at the expense of highlight headroom, so I recanted a bit. Now, as part of the Technicolor CineStyle picture setting release, the user manual mentions that one should shoot at "multiples of 160." I assume Technicolor knows what they're talking about, but the question remains.
As a response to Technicolor's recommendation, Andrew Schär conducted this test:
The noise levels are appreciably lower at the corresponding ISOs: 160, 320, 640, 1250, 1600, etc. However, this test doesn't show latitude or any sort of highlights. How much highlight loss are we talking? Is it always a best practice to shoot at ISOs divisible by 160, or is it situation-dependent (e.g., don't worry about using 160 ISOs if you want to retain highlight details)? What's the wisdom of the crowd on this?