There seems to be more fuel to this fire. More than 1 NL source telling them this... I really hope it's true.
I would have to think it is. Step back a moment and look at the big picture. 5D3 has 14 stops but only 11-12 usable by reasonable measure due to read noise. 5DS has "equivalent DR of 5D3" (14 stops). Brunhill adds to this "more ability to pull up shadows with lower noise floor" (paraphrasing). We know Canon "tuned this for Low ISO" which I'm not sure what else that could really mean other than lower noise and more DR along with this better CFA. In order to get usable images at higher ISO, I imagine you have to sacrifice SOME level of capability at the lower end, so now they have eliminated that trade off by foregoing higher ISOs for the intended audience of this camera. Here's what else makes sense. All this talk about Canon having to remake their fab lines or greatly alter the process to get the AD on the Sensor like Sony.... Canon (if this is all correct, which I have no reason to suspect not at this point) has found a way to keep making sensors just as they have been with separate AD blocks (minimizing new capital expenditures to re tool manufacturing) but making the sensor itself operate at much lower temps (as per Northlight sources) because it's not worried about 3200 and beyond sensitivity...thus creating far less potential for noise creation. This to me appears to be a perfect trade off between making a new product and keeping the company financials happy. I think my logic there is sound, but I'm happy to hear debate.
I still think people are mincing words here. The 5D III does not have 14 stops of DR. The 5D III has 11 stops of DR. You cannot ignore the read noise, and people seem to be trying to do that with these funky explanations of why the 5Ds "has the same DR as the 5D III, but also has more DR than the 5D III". None of it makes sense.
Dynamic range is a very simple concept. It is the ratio between the FWC and the noise floor. Many things can affect the noise floor...including shot noise in the signal itself. I haven't actually heard anyone from Canon officially state that this camera has more dynamic range...they just keep talking about the "noise floor". The 7D II, which nearly the same pixel size, has lower read noise. It has lower read noise because it has small pixels (something about how Canon designs sensors leads to this scaling of read noise with pixel size...not all sensors are that way). The 5Ds has the same small pixels...so, it stands to reason that the sensor will have lower read noise.
The KEY here is that...for the 5Ds to have more dynamic range, it MUST ALSO have a higher FWC than the 7D II does at ISO 100. If it has, say, 13e- RN per pixel at ISO 100, and still has a 29455e- FWC...well, it'll actually have slightly less DR than the 7D II (which has 12.9e- RN per pixel with ever so slightly smaller pixels.) The 5Ds, at 13e- RN, would certainly have less read noise than the 5D III, the 6D, the 1D X, etc. But with a 30ke- FWC, it's got less than half the FWC of a 6D!!! It wouldn't have more DR...it would have the same DR as all Canon cameras have...around 11 stops and change.
If the 5Ds has 13e- RN and say a 45ke- FWC, alright, now we're talking. That is 11.8 stops of DR...half a stop to a stop better DR than other Canon cameras. If it has a 60ke- FWC (double the 7D II...eh, I don't think that's possible with 4.14 micron pixels, especially not on a 500nm process, but let's go with it), then you have 12.2 stops of DR. Hmm...a solid stop better than any other Canon camera...but still not comparable to the 13.8 stops of a D810. So...let's just go all out and say the thing has 75ke- FWC (same as the 6D). It'll have 12.6 stops of DR...eh. For this camera to get 13.8 stops of DR at 13e- RN, it would need an FWC of 180ke-. Not gonna happen...not with 4.14 micron pixels and a 500nm process.
Let's go the other way here. Let's reduce read noise. Let's say it has 6e- RN and a 30ke- FWC. That's 12.3 stops right there. What about at 3e- RN? Bam, 13.3 stops of DR. Let's say it has a higher FWC than the 7D II...say 40ke-, and that same 3e- RN. Voila! 13.75 stops of DR.
Canon needs to reduce their read noise to Exmor levels. There is no way they are going to get enough well capacity in a 4.14 micron pixel to support more than MAYBE a stop more DR at similar RN levels to the 7D II. There are certainly things Canon could have done to reduce read noise to 3e- at ISO 100...however it would be THE unprecedented move they have needed to make for oh so, so long. To actually achieve it, Canon would have had to have moved to a newer, better process (180nm at least, smaller better), and moved all the core image processing logic (amp, CDS, ADC) onto the sensor die, and go CP-ADC (thus reducing ADC frequency considerably). Just doing that wasn't even enough for Sony to achieve the ultra low level of 3e- RN...they had to use additional innovations. They added a digital CDS stage to the readout pipeline. They also moved the clock generator to a special remote area of the sensor die to prevent it from adding uneven noise to whatever ADC units were closest to it. Finally, they designed ADC/DCDS units which adapt themselves to each pixel column, eliminating vertical banding.
I dunno. Maybe it's just me...but that sounds like much too big a leap. Especially given the rumors that the 5Ds is STILL manufactured on a 500nm process. Even more especially given that it's already been stated so many times that it has the DR of the 5D III. Yeah....just doesn't sound plausible to me. I don't think the 5Ds will have Exmor-level 13+ stops of DR. At best...I'd say 12.2 stops...with the faint hope that Canon will totally surprise me and prove me totally wrong with some truly amazing technology in the 5Ds.