I keep reading a whole bunch of reasons why Canon "should" switch to a Sony sensor for more DR, but I have yet to read one response that needs to be brought up:
In-house engineering expertise.
Canon is substantially bigger than Nikon, and as such, has much deeper pockets for Engineering R&D. If you consider the sensor a key-component of your camera (and it is), why would you outsource it to a competitor? (Apple & Samsung parallel with this issue) Canon most definitely is working on a sensor with On-chip ADC- we just don't know about it. If Sony has a patent on it, Canon is doing their best to work around it (if possible).
What happens the day that the contract between Sony & Nikon ends, and Sony triples the price of their sensor? My guess would be that Nikon says NO, and then Nikon needs to then restart their stalled sensor R&D department, which by then has a years long handicap. Canon plays the long game. The 5D Mark III may not be the best camera in all situations, but then neither is Nikon 800 (now 810). In my experience, glass is limited by physics, and bodies limited by electronics- which is why some old lenses are still made (135 f/2 was released in 1996). What photographer wants a Canon body released in 1996? I fully expect to replace my bodies every few years, but I don't plan to replace lenses often, even if a newer revision appears.
Besides, most people would say that Canon has a much better lens lineup than Nikon, nevermind CPS vs NPS customer service (heck, it's hard to enroll in NPS!)
The more people keep talking up Sony sensors in Nikon cameras, the more people start thinking that the sensor is the one part that's keeping them from becoming the next Ansel Adams. The fact that we Canon-ites can entertain the idea of getting an A7 solidifes this fact. There's a reason Nikon doesn't advertise using Sony sensors- they know that it diminishes the apparent value of the rest of the camera.
Yes, dynamic range is important. More important is the photographer's skills, and it's quite easy to fall into the trap of 'better gear = better photographs".
Just my 2 cents!
This is an interesting couple of cents, but I think it's missing the real reason people want more DR. More DR means better IQ, sure...assuming you use it right.
But if you read my posts on the subject, I'm not just or even primarily concerned with the IQ. The frustrating thing about Canon's read noise is that it involves more work to deal with
. Better gear isn't just or even primarily about better photographs. Better gear can allow that...bit when it comes to dynamic range, particularly the dynamic range gained by reducing read noise...it's the reduction in post-processing workload that matters the most (at least, to me.)
I can spend a lot of time on each individual image cleaning up noise. At high ISO on a Canon CR2, it's no big deal. The noise takes on a clean, random characteristic, and it responds very well to NR. My workload has dropped with the 5D III relative to the 7D at high ISO, as I barely have to apply any NR to get my images looking nice, unless I'm printing huge. The 5D III, however, has proven to be a more fickle tool when it comes to cleaning up the noise at low ISO. It has a massive amount of read noise, at 33-35e-, and is even more difficult to clean up than my 7D (which only had 8e- read noise).
Because of the loss in overall DR, I more frequently have to resort to bracketed shooting, which in turn leads to more processing in post to blend the HDR then process it in ACR. HDR merging isn't a flawless process, artifacts can be a problem, and it is often not just as simple as picking a key frame and removing ghosts to fix those artifacts (if the sun is in the frame, removing ghosts can make things considerably worse in some cases.)
More DR is often about more than just better IQ. I definitely want a cleaner, smoother shadow falloff in my landscapes...but primarily, I don't want to have to hassle with each and every photo I'm trying to make. I spend far too much time as it is sitting in front of my computer, processing images. Most of that is astrophotography these days...but it's still a LOT of work. Countless hours of work. Now that I'm back into landscapes...that's just MORE hours of processing. I really want more DR so I don't have to resort to more complicated, meticulous means of reducing noise in my images.