This is my Canon 6D ISO test, this shows how the image looks like at the following ISOs: 100 160 320 640 1250 2500 5000 1000 12800 25600.

To my eye, it seems like the highlights are holding out quite well all the way up to 10k ISO, while the shadows are holding out perfectly until 2500 ISO, and very decently at 5k and 10k. At it’s highest ISO setting of 25’600, though, the image does seem to fall apart quite a bit, but I could see it having some uses.

If you would like to see such a test for photographer where I could go up to the H2 setting of 100K ISO, let me know, but 25,600 is the highest the camera can go in video mode.