ISO 3200 is the limit for me when I'm shooting action shots in poor light on the 1DX.
Interesting, many people are regularly using much higher, I recall Andy Rouse, a very famous UK wildlife photographer, being happy at 10,000 even for printing and publication. What is your regular output size and medium?
I am still on 1Ds MkIII's and with the latest post processing noise software I am very happy at 800 and content most of the time at 1600, I'd have expected the 1Dx to be much better than 1-11/2 stops better than my old bodies. Just interested.
Private...it's probably a little bit of "to each their own", but I remember reading EML writing recently on this post that he doesn't like going above iso 1600 (if I remember right) and that surprised me a little bit because I regularly go to 3200 ISO.
Here's a 100% crop at 800x800 pixels, RAW, at ISO 4000. Nothing done but slight exposure bump and a pass through Nik sharpener pro and Nik define.
From the same game (later in the game when the sun was down) It's not terrible, but it's starting to go downhill.
I will go to 4000 on occasion, but I really prefer to stay at 3200 or lower if I think I might need a larger print of the shot.
The second is the same exact editing
but a much bigger crop. As you can see, it's certainly usable for a smaller print and online....I maybe should've clarified my first post in regards to image size as it relates to high ISO.