More megapixels, better photos: Fact or fiction?

Started Feb 7, 2008 | Discussions thread
John Sheehy Forum Pro • Posts: 21,549
Re: I agree it depends

Ehrik wrote:

So a "clean" photon counter is not possible?

It seems to be very difficult for large photosites. A sensor that could just count photons with high quantum efficiency would be miraculous, at least as far as shadows are concerned. The cleanest "counters" are "photo avalanche diodes", AFAIK, as they have normal read noise in electrons, but each photon causes multiple electron charges, so they have low read noise in photons.

and a factor of 5x in full well

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?

Since this is the most obvious solution (but only for having lower ISOs, of course), and it hasn't had much improvement, I would assume that there are obstacles in this approach.

Or if the well is emptied and
refilled
several times during exposure and a counter keeps track. Of course in
this
case there is a full well conceptually even if it's not limiting.

Refilling might cause glitches in counting, make more noise in the sensor, require too much processing, etc. It is an easy concept, but the implementation may be difficult.
--
John

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