Hello Tony, I've always enjoyed your videos but this one got my head scratching.
At the 4 min mark of your video you showed some numbers.
Canon 5D Mk 3 $2,800 is 16% cheaper than Nikon D800 but is has 36% less MB than the Nikon
18MP = 75% sensor usage
18MP = 75%
20MP = 83%
Nikon D800 $3,300
21MP = 58% Sensor usage
23MP = 63%
24MP = 66%
Just by looking at the numbers, it looks like the Canon is more efficient at converting anologue to digital. Again only looking at the numbers.
Comparing the two for performance, the Canon 5D Mk III has an eight-channel readout and DIGIC 5 processing engine, which means it can shoot continuously at a maximum rate of up to 6fps, while the Nikon D800's Expeed 3 engine enables it to shoot full-resolution images at up to four frames per second (fps).
Given its higher pixel count, the Nikon D800's native sensitivity range (ISO 100-6400) is more restricted than the Canon 5D Mark III's, which runs from ISO 100-25600. Nicely, both cameras have expansion settings that enable the sensitivity to be reduced to the equivalent of ISO 50, and while the D800's maximum is ISO 25600, the 5D Mark III's is two stops higher, at ISO 102400. Remmeber at these higher settings you get some serious noise, but if you REALLY need that shot, the option is there for you.
The Canon 5D Mark III has a better signal to noise ratio across most of the sensitivity range, meaning images are cleaner at pixel level. Both cameras produce images with a lower signal to noise ratio when noise reduction is turned off. For much of the sensitivity range the 5D MK III's raw files (after conversion to TIFF) with noise reduction turned off are a close match for those from the Nikon D800 with noise reduction set to its default level.
Up to around ISO 400 the Nikon D800 leads the way for dynamic range indicating that it is capable of reproducing subtle tonal gradations in highlight and shadow areas. At mid to high sensitivity settings the Canon 5D Mark III's raw files (after conversion to TIFF) have a greater dynamic range than the D800's.
D800 tends to produce more noise in low light - especially when the light is unnatural - and the lower maximum continuous shooting rate mean that it is marginally less versatile than the 5D Mark III.
Canon has put a little more thought into how professional and enthusiast photographers use their cameras. The 5D Mark III's HDR mode, for example, is much more useful for serious photographers, and the video activation is more comfortably arranged.
The is no doubt both cameras are extremely good, and choosing between them isn't easy. It's a decision that is likely to come down to personal preferences for the control arrangements, existing allegiances and the intended use.
I am a Canon user and I have the 7D Mk I, which I am extremely happy with. My friends use Nikon and Canon, some 6D, 5D and 1Dx and some D800, 810 and D3x.
Photographers who shoot primarily in good light and who are interested in capturing the maximum amount of detail possible, perhaps specialising in landscape, still-life or macro photography, will find that the Nikon D800 is a better choice.
Thanks for a super video. Appreciate you have taken the time to do such a comparison.