sensors are near their theoretical limit for efficiency,
Would love to educate myself on this. Pls can you guide me where I can read up on this statement. Thx.
There have been a number of articles posted on the subject. ideally, a photosite that could read out the charge of one photon would be perfect, if it weren't for several other limits that also apply.
ISO is basically limited by sensor noise, and there is noise even in light itself.
Here is one article, its a bit involved, because its not a simple subject.
Here is a fairly technical paper about sensor noise, which is the limiting factor in high ISO low light photography.
As I said, there are technologies that sidestep the limits by combining multiple images and averaging out noise, but they do not increase the basic sensor limits.
Low light and low iso capabilities are sometimes mixed up in this forum. As far as low light is concerned, the paper mentioned above is a really complete and well founded explanation of whats possible and what not. the theoretical limit of information contained in a photo, is to count all photons and detect their color. This perfect image will be noisy as hell. This perfect image will be limeted by lenses, diffraction, sensor efficency, and by additional noise added anywhere between the incoming light and the photo arriving on the chip card (readout noise).
where sony/nikon are better than canon at the moment is low iso area, where canon is limited by readout or other noise. the way to better IQ would be to have lower native iso capabilities, but i dont know where the actual limitation near 100 is coming from.
maybe there will be more progress in postprozessing, to get the best out of an existing raw file, example here may be astronomics, where not only bigger instruments are build but also better results are obtained from existing instruments.
and the biggest limitation was forgottenuntil now.... most of my bad pictures are bad because of bad composition, to slow camera handling (missed opportunity), or just undone pics, because the camera was at home. But the existing equipment at least allows me to practise my skills, until the really good camera is out, which will compensate for my failures as far as possible....