What compact digicam has the biggest CCD pixels?

[A complimentary Cc of this posting was sent to
Roger N. Clark (change username to rnclark)
], who wrote in article :

So how in quantum mechanics does one photon create 0.1 electron?

Do you want me to give a lecture on quantum mechanics? Wrong forum.

It only matters what photons get converted to
electrons, and it takes precisely one photon to create that electron
in the CCD or CMOS pixel.

I see, you have a very naive understanding of quantum mechanics...
Anyway, it does not matter much: the issue of QE can be addressed very
well in classical terms.

Put a neutral density 3 filter over your camera so the throughput is
0.001 or whatever factor you want to use.

Use the same exposure, and the S/N value you measure after this is
decreased 30 times. So you see that the amount of photons which
generate 1 electron matters.

By your idea, the signal-to-noise ratio is magically dependent on the
original photons incident on the camera.

Put a 0.001 density filter over your sensor. Use 1000 times larger
exposition. You get 1000 times more photons in your sample. So the
photon count S/N is 30 times lower. But the electron count S/N
remains the same.

Puff! There goes your theory that photon noise is the same as
electron noise.

Thanks. BTW, do you have a clear opinion on what full well is enough
to provide "satisfying" images *if one does no postprocessing* (view
things "as is")?

This is a subjective call.

Absolutely. I'm asking for your subjective opinion, based on your
personal experience. And everybody else is, of course, very welcome
to add their opinions.

Film is pretty noisy but produces great images.

As you demonstrate it many times, in this decade it does not make
sense to use film as the gold standard of quality w.r.t. noise. But
the human eye does not change this quick, so it makes some sense to
use the eye response as a gold standard.

But as signal-to-noise drops, how much you can enlarge the image
becomes less. I would consider film's noise the minimum.

If Velvia 50 gives S/N=20 for luminance of 18% gray, it looks like I
cannot reliably distinguish it from 0... This is for pixel size 6.3
microns, while the dot pitch on my monitor is 260 microns; quite a lot
of magnification. Maybe my eyes are not good enough...

Thanks,
Ilya

Ilya Zakharevich wrote:

Put a 0.001 density filter over your sensor. Use 1000 times larger
exposition. You get 1000 times more photons in your sample. So the
photon count S/N is 30 times lower. But the electron count S/N
remains the same.

Puff! There goes your theory that photon noise is the same as
electron noise.

Ilya,
You compare photon numbers in front of the 0.001 transmittance filter
to photons converted to electrons in the sensor's pixel.
This is completely absurd and is totally irrelevant to
the signal-to-noise that the sensor is capable of achieving.
An electronic sensor converts 1 photon into one electron
in the potential well. It only matters what photons are converted,
not what gets absorbed/lost external to the photosensitive area.

Roger

[A complimentary Cc of this posting was sent to
Roger N. Clark (change username to rnclark)
], who wrote in article :

You compare photon numbers in front of the 0.001 transmittance filter
to photons converted to electrons in the sensor's pixel.

Yes, I followed the model you proposed to show that QE does not
matter. Your model shows that it *does* matter, and the photon
Poisson noise is not equal to the electron Poisson noise. Thus using
these terms *interchangeably* is not suitable; it leads to *confusion*.

This is completely absurd and is totally irrelevant to
the signal-to-noise that the sensor is capable of achieving.

In your settings I agree that a S/N ratio *the sensor* is able to
achieve is determined by the amount of electrons generated in a cell.
However, as I said it many times, if you replace "the sensor" by "a
sensor", this statement becomes wrong as far as *photographer's* point
of view is taken:

take two sensors with different QE; make two shots with the same exposure.

You get different noise. So, from photographer's point of view
("artistic value" being the main issue), these sensors have different
S/N ratio at the same exposure.

If the full well capacities of these two sensors are the same, then,
as you say, the noise can be made equal by compensating the exposure.
From the photographer's point of view, this means that these sensors
may be used to provide the same "artistic value" with different ISO
equivalent.

An electronic sensor converts 1 photon into one electron
in the potential well.

I repeat it again: most photons are converted to 0 electrons. This
makes the electron Poisson_noise/signal much larger than photon
Poisson_noise/signal. [This discussion goes in circles, so feel free
to cut it off.]

Hope this helps,
Ilya

Ilya Zakharevich wrote:

[A complimentary Cc of this posting was sent to
Roger N. Clark (change username to rnclark)
], who wrote in article :

You compare photon numbers in front of the 0.001 transmittance filter
to photons converted to electrons in the sensor's pixel.


Yes, I followed the model you proposed to show that QE does not
matter. Your model shows that it *does* matter, and the photon
Poisson noise is not equal to the electron Poisson noise. Thus using
these terms *interchangeably* is not suitable; it leads to *confusion*.

You are not using "my model." See below.

In your settings I agree that a S/N ratio *the sensor* is able to
achieve is determined by the amount of electrons generated in a cell.
However, as I said it many times, if you replace "the sensor" by "a
sensor", this statement becomes wrong...

A sensor can be a one element sensor, same as "the sensor." I still
work with 1-pixel systems. It has 1 sensor. The sensor is one pixel.

In your settings I agree that a S/N ratio *the sensor* is able to
achieve is determined by the amount of electrons generated in a cell.

Hallelujah!!!! We've finally made progress. This is what I have been
trying to tell you for a long time.

take two sensors with different QE; make two shots with the same exposure.

You get different noise. So, from photographer's point of view
("artistic value" being the main issue), these sensors have different
S/N ratio at the same exposure.

I agree.

If the full well capacities of these two sensors are the same, then,
as you say, the noise can be made equal by compensating the exposure.
From the photographer's point of view, this means that these sensors
may be used to provide the same "artistic value" with different ISO
equivalent.

I agree.


An electronic sensor converts 1 photon into one electron
in the potential well.

I repeat it again: most photons are converted to 0 electrons.

Yes, I agree, but when a photon IS converted, it generates one electron
in CCDs and CMOS sensors.

This
makes the electron Poisson_noise/signal much larger than photon
Poisson_noise/signal. [This discussion goes in circles, so feel free
to cut it off.]

This is where the confusion is. When I say photon noise I mean those
photons that are converted to electrons. In the electronics
industry, in astronomy, and I'm sure other industries, photon
counting devices are commonly referred to as, well, photon counting
devices. By your nomenclature, they are not counting photons, but
electrons, and you would say most photons are not counted (most
devices have low QE, and even lower optical transmission * device QE).
But the electronics/astronomy fields do not use your nomenclature.
I know who you mean, and while a legitimate point of view, it is not
the standard nomenclature in use. When I say photon counting, it
refers to the photons that get converted to the electronic signal.
And it is that generated signal we measure and which ultimately
influences the signal-to-noise ratio that can be gotten from that system.
Agreed?

Roger