That’s a really nice Carina Tony, very nice colour tone variation throughout the nebulosity
I cannot speak for Canons but the older Nikon’s has their best at ISO800/1600 like the D700; this I found out through my own testing.
The newer ones like the D7200 and D810 have their peak at ISO400 but are still exceptional at ISO100. I’ve tested both cameras and found that after ISO400 the dynamic range drops away faster than the read noise and after ISO800 the RN virtually stops dropping while the dynamic range plummets.
So for every day photography I rarely go past ISO800 in any light because the read noise doesn’t improve so the dark areas are no better.