Nikon D5 comparing ISO 800 to 66535

Nikon D5, AF-S NIKKOR 14-24mm f/2.8G ED, ISO 800, ƒ/11, 1/200–4 - Alienbees B1600 w/45º reflectors, PocketWizard Plus 

I shot this group photo of 400 musicians and to get the most even light I ended up bouncing 4–Alienbees B1600 strobes with 45º reflectors bouncing off the ceiling. I also used the ExpoDisc to get a custom white balance.

This is pretty heavy crop of the above photo.

Nikon D5, Sigma 35mm ƒ/1.4 DG Art, ISO 7200, ƒ/5, 1/200

Now this is a performance shot with available light. If you notice the light on the orchestra at the bottom wasn't very even and this is why I shot with strobes rather than using available light for the group photo.

Now just to give you an idea of how good ISO 7200 looks here is a enlargement of similar size to the first photo.

Pretty awesome if I say so myself.

Nikon D5, Sigma 120-300mm ƒ/2.8 DG OS HSM S, Sigma TC-2001 2x, ISO 66535, ƒ/5.6, 1/200

I was blown away with the ISO 66535 quality of the french horn player.