It is full frame and utilizes the same sensor as the Canon Mark iii. The 6D is comfortable to handle, the body is thinner and lighter than the 5D, which in comparison feels like carrying a brick around. It’s well balanced with a variety of different lenses, the Canon L Series 24m-105mm or 50mm f1.2 are both superb.
Where the 5D Mark II & III pip the 6D is in point focus. The 5D has a whooping 61 whereas the 6D only has 11, although personally I only ever use the diamond of 9. Also you can go one step further with shutter speed on the 5D, 1/8000 instead of 1/4000…
The 6D uses SDHC cards (rather than CF) which have become the standard, so much so all MacBook Pros and iMacs have an onboard SD slot.
The LCD screen resolution on the 6D is better, it has less noise in low light, it has an ISO boost, greater dynamic range, shoots more images per second in continuous shooting, does HDR photography and is so quiet you barely hear the shutter cock.
On top of that the 6D has GPS and WiFi which means you can use your phone/tablet or laptop as a remote for your camera, but not just for taking photos, you can control all the menu/setup options through WiFi too.
The 6D is a great addition to our equipment cabinet at DAS and for only £60 (members) or £75 (non members) for a day it is dirt cheap. Coupled with the Canon L Series 50mm f1.2 or the L Series 24mm-105mm the real challenge is trying to take a bad photo!