From: David Dyer-Bennet on
Ilya Zakharevich wrote:
> [A complimentary Cc of this posting was sent to
> David Dyer-Bennet
> <dd-b(a)dd-b.net>], who wrote in article <462456e1$0$272$8046368a(a)newsreader.iphouse.net>:
>>>> But removing the IR filters probably remains undesirable (for a
>>>> low-visible-light camera) because lenses don't focus IR and the visible
>>>> spectrum close enough together to really want both at once; you really
>>>> have to choose one or the other.
>>> Not necessarily: For low-light work under incandescent or candlelight or the
>>> like, the incident spectrum will be heavily tilted to red and IR, and I'd
>>> think that red and IR wouldn't be as bad for focus discrepancy as IR would
>>> be in landscape work. But even in landscape work, one is often stopped way
>>> down, so it might not be that much of a problem.
>> Hmmm, yes, true, red will predominate pretty heavily, and IR will very
>> likely focus closer to red than to blue with pretty much any lens.
>
> Irrelevant. With any half-decent lens, red and blue will focus at the
> same plane. :-( ;-)

Yeah, well, reasonably close, certainly.
From: Roger N. Clark (change username to rnclark) on
Ilya Zakharevich wrote:
> [A complimentary Cc of this posting was sent to
> Roger N. Clark (change username to rnclark)
> <username(a)qwest.net>], who wrote in article <46243DEE.1020803(a)qwest.net>:
>> So for current cameras, 8x or 3 stops is about what we can
>> hope for by removing the Bayer and IR filters in current
>> digital cameras, and another stop increase with higher QE
>> detectors.
>
> This is in accordance to what I was claiming about 2 years ago, when
> my calculations have shown that digital cameras (of that time) worked
> at about 5-10% "throughput QE". However, these calculations where
> based on (flawed) data Roger put on his website; my current estimates
> of the same number are closer to 14%.
>
> Which means that no amount of tinkering can bring a gain above about 3
> stops. (In particular, the Bayer filter itself eats about 1.5stops of
> the signal.)

Heees BAAAAACK!

As usual, you come in with sweeping conclusions and broad
accusations but supply zero evidence either for your case
or what you are accusing others of.

What flawed data?

Last I remember you were arguing for pixels way smaller than
a micron for which we calculated that a pixel would get
only a photon or so per pixel in an average exposure.

I also remember you being adamant about the QE of digital cameras
being extremely low, well below 1 percent. So now you are claiming
more reasonable levels. Why the change? I find it interesting
that you say flawed data but then cite similar numbers from
my studies.

Digital Cameras: Counting Photons, Photometry, and Quantum Efficiency
http://www.clarkvision.com/imagedetail/digital.photons.and.qe

You might also catch up on a lot of data since you last graced us
with your presence in this newsgroup; see:

http://www.clarkvision.com/imagedetail/index.html#sensor_analysis

Also see some of the references, including the more recent
Kodak sensors which show a wealth of information, and note that
the data from sensor manufacturers, like Kodak, the astrosurf
pages by Christian Buil, mine, and others are in agreement.
So again, what flawed data are you talking about?

Roger
From: Ilya Zakharevich on
[A complimentary Cc of this posting was sent to
Roger N. Clark (change username to rnclark)
<username(a)qwest.net>], who wrote in article <462C265A.5020101(a)qwest.net>:
> I also remember you being adamant about the QE of digital cameras
> being extremely low, well below 1 percent.

It would help if you the things you remember bear some relation to reality...

Hope this helps,
Ilya
From: Roger N. Clark (change username to rnclark) on
Ilya Zakharevich wrote:
> [A complimentary Cc of this posting was sent to
> Roger N. Clark (change username to rnclark)
> <username(a)qwest.net>], who wrote in article <462C265A.5020101(a)qwest.net>:
>> I also remember you being adamant about the QE of digital cameras
>> being extremely low, well below 1 percent.
>
> It would help if you the things you remember bear some relation to reality...
>
> Hope this helps,
> Ilya

for example:

Ilya Zakharevich wrote on Dec 20, 2005 in rec.photo.digital, in thread
Noise levels as a function of pixel size:

> One example: assume that we are in the settings of my old "physical
> limits of digicams" example; let me recall:
>
> the QE of digital sensor which produces noise similar to Velvia 50
> is about 0.004;
From: Ilya Zakharevich on
[A complimentary Cc of this posting was sent to
Roger N. Clark (change username to rnclark)
<username(a)qwest.net>], who wrote in article <462D60A1.8020107(a)qwest.net>:
> >> I also remember you being adamant about the QE of digital cameras
> >> being extremely low, well below 1 percent.

> > It would help if you the things you remember bear some relation to reality...

> for example:

> > One example: assume that we are in the settings of my old "physical
> > limits of digicams" example; let me recall:
> >
> > the QE of digital sensor which produces noise similar to Velvia 50
> > is about 0.004;

Anybody who can read would see that this is a discussion of the noise
of the film camera, not of a digital camera.

Hope this helps,
Ilya