I spent this afternoon reviewing some of the problem that people are having with the 1DX. These problems mostly centered around auto-focus. I through on my most challenging auto-focus lens, the EF 400mm diffraction optics (DO) image stabilization (IS) lens. I have admittedly had some trouble getting focus lock, but only in situations where I would expect even more difficulty with a less advanced camera. Ultimately, there are three factors that you need to weigh before purchasing this camera.
1: do you really need 12 fps, and the ability to retain focus throughout continuous shooting? On the 1D X, with a fast enough CF card (1000X), you can get almost 35 frames – continuous – in RAW mode before the buffer to disk ratio collapses your frame rate. With its second Digic dedicated to metering and AF, you can shoot and maintain focus continuously. In JPG, you can get a lot, lot more (I don’t know how many before it slows down or even if it does ever slow down). I am reluctant to push this to its upper limit – if you need to shoot more than 100 low quality jpgs in a row, then you should be shooting in video.
2: Do you need the better weather seal? If you have to shoot the bride and groom running through the rain to the limo, and your 5D gets soaked and you can’t shoot the reception with your best tool … uh oh, sux to be you, right? Or maybe you just stay out of the weather, and you miss what could have been some great, fun shots, you’ll wish you had the 1D X.
3: The 1D is sturdy,and handles great, but does require some strength to sling with precision. I handhold with the 2X and 400 DO, and have been sore the next day after a 6 hour shoot.
If these three requirements are not important to you, then don’t buy this camera. It’s not for you.