It seems the thing people talk most about with cameras today is ISO performance. So here is some examples/tests of the D3s & 1D4 ISO performance.
By the looks of things, Nikon's D3s is definitely outperforming the Mark IV at high ISO.
See for yourself: http://www.neutralday.com/
I cannot vouch for the tester/reviewer here.
Yes, I have owned a Nikon D3s, and every single digit D-series body before it, as well as every single digit F-series bodies up to the F3, and have used them extensively under all extremes and conditions. As a photojournalist for the past 26 years, Nikon has been my choice. Until now.
Now I have begun to seriously contemplate a change-over to the Canon 1D line because of the exacting standards and demands in today’s print media.
As the bar is constantly set higher in terms of resolution and manageable noise for publication purposes, I have found the Nikon product lagging. Most photojournalists do not have time to play around with photoshop or other software to refine their shots, especially when they are shooting a few thousand at a time, and need to have them filed immediately thereafter. Very little today, (in print media), is shot over 6400 anyways, so super high ISO’s aren’t really that important at all. Besides, the photographer isn’t the one who decides which shots are to be used, that’s the job of the editor. Full Frame or 1.3 crop, isn’t really relevant, not by today’s digital print/publishing standards. Detail, and sharpness, as well as that “right moment” which comes with speed are the determining factors that count.
I came to this site looking for valid comparisons between the 1D MK IV & D3s, but found only squabbling amongst amateur users. I would appreciate it if there were any MK IV owners out there who could share their experiences and impressions.