Is time to draw some conclusions and share some of my my personal thoughts about those cameras.
Output – prints: I also printed out the comparison images with typical 300 dpi resolution that gives you approximately A3 size prints. Printing those images clearly reduces perceptible noise and adds value by making those moments more tangible. The differences between the D4 and 1D X become even smaller.
On the second print I resized files to A4 format and slightly increased the print resolution to 360 dpi (Epson Stylus Pro 7900 and Premium Luster Photo Paper). As could be expected, the differences between the two cameras increased and higher resolution 1D X will give you slightly better image quality.
Autofocus performance: Nikon D4 AF sensitivity has been increased to -2 EV, which is around the physical limit of human visibility through an optical viewfinder. When shooting night time (using only city glow light) the Nikon D4 autofocus still works and Canon is out of the game. In poor lighting conditions (our athletics action shots) 1D X shows its immense processing power and autofocus is quicker.
White balance: 1D X offers more pleasing colors when shooting in AWB. D4 offers more convenient and exact settings for white balance.
Buffer memory: Nikon D4 buffer memory is over two times larger than 1D X.
Battery performance: Started the athletics day with both cameras charged up batteries and ended the day with 1D X at 39% remaining (2425 images) and D4 at 14% remaining (2457 images).
The D4 has backlit buttons. This is a really great feature, but it would be even better if there was an option to leave the lights on for the time I need them on. Backlit buttons helped me a lot then I was testing autofocus. I also liked the more peaceful blue color of D4′s display.
Nikon D4 has elegant and playfully curvy design. Nice to see that D600 and D5200 share some of that sexy curvature design. When working with that camera I felt that it is a beautifully designed and precise piece of equipment. One could even say that D4 cuts images like surgical scalpel.
Canon 1D X design is somewhat cold, functionalist and technical. Nevertheless, in landscape position the camera sits in the hands better than a Nikon D4. When working with that camera I felt I was operating with powerful chainsaw instead of scalpel. High performance and operating speed of the camera will get you the shots you need. The robust 1D X is slightly bigger and heavier than the D4.
In portrait position both cameras positioned their AF-ON buttons in illogical locations compared to landscape mode. Dear Nikon, please use shorter XQD or SD cards to shorten the card door and to put the buttons at the right locations:
One more observation on D4 – the upper part of D4 grip is too edged against the middle finger. The same problem with the D600. To my surprise D600 battery grip had this place designed perfectly!
My last observation is related to how the ISO values are displayed within menus and displays. It would be very nice if Nikon showed numeric values of ISO next to Hi 0,3 – Hi 4 names.
I hope my feedback was helpful. Dōmo arigatō.
Both cameras are professional tools – D4 is a small step for Nikon users and 1D X is a big step for Canon users.
It is difficult to find major differences in the most important characteristics of these cameras – image quality and autofocus performance. The Canon has a minor resolution advantage, but 18Mp vs 16Mp is not that big of a difference, as you can see from the print sizes above. It may also perform better when shooting JPGs with auto white balance, but we don’t really do that :)
It is very difficult to provide exact comparisons on autofocus performance, as repeatable situations and totally consistent photographers are hard to find in real life. Even more variables are introduced by the growing number of AF settings these cameras have – we can’t claim to have tested these thoroughly.
It would have been nice to test different settings, including automatic AF point selection, as the 1D X is Canon’s first camera to have a high-resolution color sensitive metering sensor providing input to the AF system to improve focus tracking and automatic AF point selection. This should provide an advantage over the 5D Mark III, which has a similar AF system, but a simpler metering sensor. Nikon full-frames have taken advantage of color information provided by the metering sensor for a while already.
In the all-important issue of body design, my vote goes to Canon – it has smooth curves, as if carved out by forces of nature from a solid block of magnesium over eons of time; the Nikon looks really lumpy in comparison :) It is actually quite easy to switch between the cameras without any great discomfort. Still, I agree with Tom that the vertical orientation AF-on button is lower on the D4 than one would expect.
As for why these pro bodies should be preferred over their lesser brethren, I ended up finding far fewer reasons than I expected at the start of the test. In image quality for example, Nikon’s other full frame bodies are better than the D4 (at least at ISOs they are capable of); on the Canon side, the 5D3 and probably the 6D are quite close the 1D X as well. There used to be a significant difference between AF capabilities of pro and non-pro bodies, particularly with the Canons, but at least with the 5D3, the difference has become rather small. Nikon has been putting quite capable AF systems into all of its full-frame bodies, going back to the D700.
That leaves speed and weatherproofing as the main arguments for using the 1D X and D4. Maybe durability as well, if we look at the rated shutter life that is 2-3 times that of the lesser bodies. The price of these advantages, however, is at least twice the cost and also a lot more weight constantly hanging from your neck/shoulder. Of all the cameras that we tried during this test, my choice would be the 5D Mark III, as it can handle almost any photographic scenario at least reasonably well, or maybe even the D600, which has very few compromises squeezed into its small body and reasonable price tag, least of all in the area of image quality, where it was one of the top contenders.