High ISO = Low noise + Shadow detail

[dpjpandone]

I'm doing research on this topic, this first post is a temporary placeholder where I will link to relevant threads and articles on the subject. Once I have gathered as much data as possible I will replace with a properly formatted essay.

https://www.magiclantern.fm/forum/index.php?topic=24379.0

[dpjpandone]

Important quotes from alex from thread: https://www.magiclantern.fm/forum/index.php?topic=24379.0

-If highlight clipping is not an issue, and you have already maxed out aperture and exposure time, feel free to use ISO 6400. On 5D3's 1080p regular (non-crop) video mode, I'd expect it to be a bit cleaner than 3200 (by 0.5 stops) or 1600 (by 1.15 stops).

-all else being equal, higher ISO is going to give *lower* noise. That is, 1/30 f/1.4 ISO 1600 is going to be noisier than 1/30 f/1.4 ISO 3200 (by 0.65 stops). In the same way, 1/30 f/1.4 ISO 3200 is going to be noisier than 1/30 f/1.4 ISO 6400 (by 0.5 stops), assuming you will be normalizing the exposure in post to get comparable renderings.

So, as long as highlights are not clipped, increasing ISO from 1600 to 6400 is going to give lower noise in shadows - by 1.15 stops (yes, a little more than one full stop). Of course, this shadow improvement will cost you exactly 2 stops of highlights.

The above numbers apply to 5D3 in 1080p mode (3x3 binning). Things will be different in 1:1 crop mode (ISO 6400 no longer providing a noticeable benefit, but that's not applicable here), or on other cameras (where the DR figures may be slightly different).

Don't take my numbers from granted - feel free to do the following test, on the same static scene:
1) 1/30 f/1.4 ISO 1600 (this will be best in highlights)
2) 1/30 f/1.4 ISO 3200
3) 1/30 f/1.4 ISO 6400 (expecting to be best in shadows)
4) 1/15 f/1.4 ISO 1600 with FPS override (expecting shadows as good as #3 and highlights as good as #2)

Quotes from Danne: https://www.magiclantern.fm/forum/index.php?topic=23041.msg241276#new

-iso 100 on 5diii and without exposing to the right the shadows will crack sooner than iso 800.

- You can do a simple test by shooting two matched files with iso 100 and 800. Just change shutter speed to match exposure. Then lift shadows in post. Iso 100 works best when minimum shadowlifting is needed. Then you get noiseless iso 100. Otherwise iso 400 and higher will reduce shadow issues.