5) 6 fps....not the 6.9fps/7fps we saw in the earlier specs. That one item is a near deal breaker for me and why I'm strongly leaning towards the 1Dx. I have a 5Dmk2 and a 7D, I shoot work across the spectrum....kids...high school...weddings...studio...sports. I need the higher frame rate and 8fps does that for me. I'm not looking to have "a camera for X and a camera for Y and a camera for Z". I just want one and a backup body. The 5D3 does not go far enough for me to do that if I sell the 5D2 and replace it with the 5D3. It comes close, but I'd still be shooting the 7D for the frame rate.
What could make the difference is if the AF/Metering in the 5D3 is improved enough over the 7D to compensate for a lower frame rate....in other words, I might get fewer shots in the burst, but the AF improvements result in more of them in solid focus. In addition, if the 5D3 shares the 1Dx's ability to shoot RAW's of 50-60 frames with a decent CF card before the buffer starts to complain, that could, with improved AF, offset the 6fps vs. the 7D's 8fps vs. the 1Dx's 12fps. I'd be happy if I can shoot 6fps and get 30 RAWs before the buffer causes the frame rate to stutter.
So, if the 5D3 can shoot 6fps sustained for 30 RAW shots, with AF and metering resulting in a higher number of in-focus and well exposed images, I'd give it serious consideration over a 1Dx. If it's ISO noise at at 6400 is improved by 1 to 2 stops, that will be a bonus. If it cannot perform at these levels, I'm going 1Dx to get to where I need to be.
I'd much rather spend $3500 on a 5D3 than $6800 on a 1Dx if I can get 90% of what I need and no deal breakers. My gut tells me the 5D3 will not do this, but I'll wait until it's out and in some folks hands before deciding. I have time, not like I need to buy a body today or in the next 3 months.
Thanks for your thoughts.
How many frames can you get with your 7D before buffer stutters? It seems to me that fps is not the best metric; maybe number of sustained frames before buffer fills is better performance measure. That, in turn, is clearly a function of shutter speed being used and file size (RAW vs JPG) - and that changes for every shooting situation. The fastest shutter speed is limited by the available light and lens being used.
With my 7D, I shoot my dog chasing other dogs in dog park. On a sunny day, I typically shoot in AI Servo mode at ISO 400 at about 1/250 sec shutter speed and f/8 with 70-300 zoom, which results in less than 30 sustained RAW frames (25 MB/frame) before buffer fills. I'm very happy with this.
I could use even higher ISO with faster shutter speed, and get more sustained frames, but this would reduce IQ. Some performance trades need to be made.
The 7D rating of 8 fps must be quoted for some shooting condition, but I honestly do not know what that is. I could not find any such spec in the 7D user's guide.
Obviously, the maximum number of sustained frames is achievable in lots of light with the fastest shutter speed available.
In the end, I think the performance difference between 6 fps and 6.9 fps quoted for the 5D3 would be very hard to measure. And not that relevant.