More megapixels, better photos: Fact or fiction?

Started Feb 7, 2008 | Discussions thread
Eric Fossum
Eric Fossum Senior Member • Posts: 1,376
Re: I agree it depends

Ehrik wrote:

Eric Fossum wrote:

There is still a factor of 2x in QE to be gained, at least,

With a Bayer sensor? Or by replacing the colour filters with something
that doesn't waste photons?

Well, between silicon device engineering, optics, and perhaps filter engineering. I am still thinking in the context of RGB CFAs.

and a factor of 5x in read noise,

So a "clean" photon counter is not possible?

Again, I am talking about incremental improvements. Buried channel source-follower or p-channel SF are possible ways to help.

and a factor of 5x in full well

Again, incremental improvements. Also, swing on the SF output and signal chain, and conversion gain are also related to full well. All 3 pieces have to match. No sense having a huge full well if it saturates the output amp, right? And conversion gain (uV/e-) needs to be high to reduce read noise.

I don't see why there is a theoretical limit. If the sensor is built
more in 3D
and the electrons are led deep down? Or if the well is emptied and
several times during exposure and a counter keeps track. Of course in
case there is a full well conceptually even if it's not limiting.

Well, 1.4 or less micron pixel pitch does not leave a lot of room for other stuff in the pixel. If you are asking about more dynamic range that is a different story and related to other factors besides pixel design.

Sorry for being so curious.

Hardly a problem!

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