« on: August 22, 2012, 06:11:04 PM »
I have used both for about a month each. I can't tell a noticeable difference between the 1D X and the 5D3 in terms of image quality, particularly at lower ISOs. At higher ISOs there is slightly less noise with the 1D X. However, I've noticed I can bring the shadows a little bit better in post with 1D X files than the 5D3 ones.
In terms of shooting itself, the 1D X is a tank, and it felt that way in every way. It's noticeably more solid than the 5D3 with a battery grip. The shutter feels and sounds better on the 1D X. However, I do miss the silent shooting mode on the 5D3, because the silent mode on the 1D X is a joke. I could take the 1D X to an outdoor shoot in the pouring rain without worrying about it at all. The much faster frame rate allows you to take action photos with ease. If you have a clear view of the object, you can't miss it with the 1D X. It focuses fast, and keep the action sharp throughout the entire sequence. The AF is also noticeably improved on the 1D X, especially in lower light. Most of my lenses lock focus faster on the 1D X than on the 5D3. Overall, the 1D X feels much better in my hands than the 5D3, which in turn, felt better than the 5D2 I previously had.
Those are just my personal observations...