From: John Sheehy on
"David J. Littleboy" <davidjl(a)gol.com> wrote in
news:etebdm$lv6$1(a)nnrp.gol.com:

> No. I think what John is saying is orthogonal to sensor size
> arguments. He's arguing that for a given sensor size, one wants as
> many pixels as one can get. Roger is arguing that for a given number
> of pixels, one wants the largest sensor you can get.
>
> I suspect that they're both right.

Yes, if that is what Roger is arguing. There are legions of people,
however, in other web forums that quote Roger as proof that bigger pixels
are always better, in all situations, and that the "megapixel race" is a
race to nowhere. He could be clearer if he means what you say, but I get
the impression that he does believe that subdividing a given pixel real-
estate into smaller pixels lowers the bottom line in image quality.

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John P Sheehy <JPS(a)no.komm>
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From: John Sheehy on
John Sheehy <JPS(a)no.komm> wrote in news:Xns98F5A1C552A9Fjpsnokomm@
130.81.64.196:

> There are basically three categories in the read noise vs ISO category;
> Cameras like Canon DSLRs that have less read noise at ISO 1600 than ISO
> 100, in electrons, cameras like the Pentax K10D which have the same read
> noise in electrons at all ISOs, and cameras like my FZ50, which does a
> very good job of readout at ISO 100, but gets more read noise in
> electrons at ISO 100.

That should have been "at ISO 1600" in the last line.

Does usenet have editing yet? :)

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John P Sheehy <JPS(a)no.komm>
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From: David J. Littleboy on

"acl" <achilleaslazarides(a)yahoo.co.uk> wrote:
>
> But anyway I was referring to the fact that, from reading your
> previous posts, I'd have expected you to make some derogatory remark.
> At least, that's what you seemed to do every time someone else
> mentioned higher pixel density as an advantage for a sensor.

That's because up to now, it has always been in the context of a smaller
sensor.

David J. Littleboy
Tokyo, Japan


From: David J. Littleboy on

"Doug McDonald" <mcdonald(a)SnPoAM_scs.uiuc.edu> wrote:
> David J. Littleboy wrote:
>
>> No. I think what John is saying is orthogonal to sensor size arguments.
>> He's arguing that for a given sensor size, one wants as many pixels as
>> one can get. Roger is arguing that for a given number of pixels, one
>> wants the largest sensor you can get.
>>
>> I suspect that they're both right.
>
>
> It is certainly not true that for a given sensor size, one wants
> as many pixels as possible. One does not want pixels so small that
> no or very very few lenses can make use of the resulting sensor
> resolution, because smaller pixels result in worse very low light
> noise.

The point/claim is that pixel binning (or noise reduction plus downsampling)
will result in the same image as the larger pixels would have in lower
light. One is collecting the same number of photons, so this should/might
work.

Meanwhile, system (lens + sensor) resolution (MTF) is always improved by
having more pixels, even if only marginally, in the situations where there's
enough light for the smaller pixels. And there are lenses that have lots of
resolution at (any prime 85mm or longer at any f stop or medium wide/normal
primes at f/5.6 to f/11, for example).

David J. Littleboy
Tokyo, Japan


From: acl on
On Mar 17, 2:37 am, "David J. Littleboy" <davi...(a)gol.com> wrote:

>
> Meanwhile, system (lens + sensor) resolution (MTF) is always improved by
> having more pixels, even if only marginally, in the situations where there's
> enough light for the smaller pixels. And there are lenses that have lots of
> resolution at (any prime 85mm or longer at any f stop or medium wide/normal
> primes at f/5.6 to f/11, for example).
>

Having more and therefore smaller pixels and binning also means we're
oversampling. So we can use an antialiasing filter that blurs less,
resulting in sharper downsampled images (in other words, the transfer
function of the AA filter can start curving downwards at higher
frequenciesthan it does now). Of course this has to be balanced
against fill factors, noise from electronics etc affecting the S/N
ratio.

Still, I have never had any doubt that eventually (and I don't mean in
20 years, but earlier than that) we'll end up with very high
resolution sensors and will simply downsample to whatever we want,
depending on output requirements and sensitivity demands. I cannot
believe that read noise etc cannot be overcome. For example, there
must be hardware binning techniques to reduce readout noise per binned
pixel to less than simply reading out at the max resolution and
downsampling (JPS I think meantioned something already).