A smaller pixel (i.e. a 7D or G12) can theoretically attain similar or even better dynamic range if you keep electronic noise low. The story is certainly more complex than this when you factor in all the details that affect sensor efficiency and IQ, such as quantum efficiency, ADC gain, etc...but in rougher terms: pixel size and electronic noise both significantly affect the dynamic range you can get out of a sensor.
Thanks for your response. I guess no one else knows the answer
What I gather, then, is that it's all about read noise. Even without doing the math, it doesn't take a rocket scientist to figure out that when comparing an APS-C 7D with 18 megapixels to a full-frame 5DIII with 22 megapixels, each pixel on the 7D's sensor is much smaller. If I understand correctly, the reason it can match the 5DIII's DR is because it's read noise is lower? I'd imagine that the 7D's read noise must be substantially lower than the 5DIII's to make up for the difference in pixel size.
Aye, the 7D's read noise is quite a bit lower (although not nearly as low as an Exmor sensor, which ranks in at 2-4e-). I think the 7D has around 17-18e- read noise at ISO 100, which is roughly HALF that of the 5D III. I am honestly rather baffled by the read noise of the 5D III sensor. For all the progress that is apparently possible in the area of read noise, and how important it is to maximum DR, it really surprised me to see it JUMP from the 5D II's 27-28e- to over 33e-. Truly has me baffled. Either Canon is just simply not paying attention to the desire of so many of their brand-locked photographers for better DR, or they just don't care...either way, its a pretty major step back.
If so, the obvious question is why the read noise is so high on the 5DIII. In comparison, the read noise of a G12 must be insanely low to come so close to the 7D and 5DIII in DR. How's this possible?AYE! That would be the question indeed!
I don't have any details about the G12. Either Canon has found a way to greatly improve the SNR of the G12, or it must have pretty low read noise. It is a substantially different sensor than those found in Canon DSLR's, though...it may be backlit (which, much like microlensing, can greatly increase quantum efficiency), and if so, that would indeed help improve SNR. Unless Canon started work on the G12 sensor so late in the game that they couldn't migrate any of the read noise/QE improvements to the 5D III sensor, the ridiculously high read noise of the 5D III (which is the highest of any camera over the last several years, as far as I am aware) is completely unwarranted in my opinion. As such...the only logical conclusion I can really come to is that Canon simply does not care about low-ISO anymore. Their push for "improvements" would then seem to be driven by three large but very specific markets:
* Video (which is rather annoying for stills photographers, who used to be the primary drivers of DSLR use)
* Wedding photographers
* Sports/Photojournalist photographers
Canon seems to have entirely lost site of other forms of photography, such as:
* Landscapes (resolution and DR, DR, DR!! You can never have enough DR for landscapes.)
* Studio (resolution)
* Portraiture (DR)
* Wildlife (resolution, sometimes DR)
* Astrophotography (Noise floor!! Noise is a massive killer for astrophotography.)
* Macro (resolution and DR, but NOISE can be a big one.)
The really sad thing is, when I check local stores, and ask friends about local stores in their areas...the D800 is in HUGE demand (more requests than for the 5D III)...but the 5D III is what sells. The primary reason I get is that they have
5D III's...but they don't have
D800's. If Nikon could get their manufacturing and supply chain in order, they might actually sell enough D800's to really hurt Canon, which might force them to think about all the photographers they are leaving behind in their relentless quest to fill the HDSLR void and satisfy the evil hordes of wedding photogs, sports photogs and photojournalists.
Personally, I feel like I'm in a bit of a bind. Few Canon photogs I know have ever said anything bad about Canon support. I've had a few experiences with them myself, once for a body and twice for lenses. Their turnaround is pretty quick, their service is pretty excellent, and the quality of their work is stellar. I have not heard the same from Nikon users, even die hard Nikon fans...from the way it sounds, Nikon support is anywhere from lackluster to terrible. Canon also has support centers pretty much everywhere in the world, and turnaround is pretty quick wherever you are, but I've not heard the same about Nikon. There are also what seem to be ever-present supply problems for Nikon gear, particularly professional-grade gear, in general. I've never once had problems finding Canon gear, online or locally, for anything from a small replacement part to expensive L-series glass. I might even be a Nikon user right now if it wasn't for the fact that the local stores didn't have the entry-level DSLR and lenses I wanted way back years ago when I first got into photography...all they had was a display model with a different lens (well, and the Nikon menu system...never cared for it, nor their body ergonomics. I clicked pretty quickly with Canon's scroll-less and color-coded menu system, and I loved their pro-body ergonomics...which are some of the things that ultimately swayed me towards Canon, that and the fact that the local stores actually had the Canon gear I wanted.)
Anyway, back to the bind. My landscape, macro, and astrophotography could really benefit from lower noise and better shadow recovery. Particularly my landscape work, which I haven't done much of over the last 8 months, and none of whatsoever this year so far. I always find myself needing to push shadows around, and they have never really looked all that good, on any of the Canon cameras I've used (450D, 7D, 5D II). My options are either to add Nikon to my overall kit, deal with a menu system which irks me and body ergonomics that don't fit my hands right...deal with what I've got...or deal with what Canon has to offer. None of those options really solve my problem well, and the only one that solves it at all will also cost thousands of dollars for a new body (D800) and a couple lenses to cover the bases...such as a 14-24 and maybe a 24-70. Thats about $7000 worth of gear...something I can't afford at all right now (I can't even afford a 5D III, which I expected to list for around $3000, some $200 over budget already.)
All I can say is its rather frustrating
when your chosen brand just forgets
you and shows no interest in even demonstrating they actually have not forgotten you, or that they are working on the problem, or that they have even acknowledged a problem (or gap, or discrepancy) even exists between them and their customers. Quite frustrating. So yes...it blows my mind that the 5D III has such atrocious read noise, when Canon has certainly done better in the past.