Re: Dinosaurs

cjcampbell wrote:

Roger N. Clark (change username to rnclark) wrote:

cjcampbell wrote:

A little honesty would be greatly appreciated here. If you really have
data that shows the quantum limit has been reached, lets see it.

All of the above links were referenced from my pages, and prove
the point.

How about a reference that shows real data that supports
your contention?

What contention? I am asking how the manufacturers are producing
cameras with more pixels with less noise without increasing the size of
the sensor, despite your saying that they cannot.

See:
http://www.clarkvision.com/imagedetail/digital.signal.to.noise
See figures 1, 2, tables 1, 2, 3, 4, 5. The square root
dependence of the plot proves photon noise (Poisson statistics)
limit has been reached. There are many other references at the end
of the page that show the same results.

Then see:
http://www.astrosurf.org/buil/20d/20dvs10d.htm
The plots at the end of the page prove the D70, 10D and 20D
are photon noise limited (the straight line proves that).

But then, you say
later on:

I think what you and Stacey are seeing is that manufactures have
improved their electronics over the last 5 or so years to get
their cameras up to the photon limits the CCDs and CMOS sensors
had all along. They added microlenses to make the fill factors
100%. The sensors were always capable of producing at the
photon noise limit, and have been so for years before consumer
digital cameras came out.

You also seem to ignore the fact that I said that quantum efficiencies
of the sensors in consumer cameras could be improved by 3 to 5x,
so there is room for improvement.


So you say that there is room for improvement. Perhaps I misunderstood
you when you said that the large sensors of today are necessarily
better than the small ones because the limit of quantum efficiency had
been reached.

My first post in this thread read:
"The problem with this whole thread is that physics is being ignored.
Sensor noise in better digital cameras, both DSLRs and P&S, are already
photon noise limited at their quantum efficiency (QE). QE's run
>20%, typically 30%. So there is only a factor of 3 to 5 improvement
that is possible. Basically noise in digital cameras are limited
by photon statistics, and the number of photons incident on the
Earth from the sun is finite."

I hope you will understand that when someone starts
throwing around the equations of light fall-off from Arcturus in order
to prove something about photons striking pixels that my baloney meter
is likely to peg.

It was Alpha Lyra, and it is the reference standard used in Astronomy.
It ia a super calibrated light source that is free for all to
use.

You have made the assertion:
"And yet, the manufacturers continue to produce cameras
where each generation has lower noise than the previous
one, despite the fact that they have the same size sensor."

What data proves this? While manufacturers have improved read
noise, the high signal regime is controlled by how many photons
can be collected, and this is basically controlled by
pixel size and fill factor.

Roger
.

Relevant Pages

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