From: Bates on
On Jul 17, 12:08 am, John Sheehy <J...(a)no.komm> wrote:
> Bates <nw1...(a)gmail.com> wrote innews:2917f6ca-48e7-4c2e-a8d2-b0906a2dcfdb(a)l42g2000hsc.googlegroups.com:
>
>
>
> > On Jul 15, 9:22 am, John P Sheehy <j...(a)no.kom> wrote:
> >> I've made a direct comparison of RAW data per unit of area in the
> >> deep shadows of ISO 100 between the FZ50 (1.97 micron) and the 400D
> >> (5.7 micron). Exposure is the same, same Av (f/4.5), same Tv
> >> (1/100), same real focal length (22mm), both shot at "ISO 100" pushed
> >> to ISO 13,500. Large crop is 100% for FZ50 (0.4MP), and small crop
> >> is 100% for 400D (0.05MP), and the other two are the other camera
> >> scaled to the 100% crop of each. As I already knew, the bigger
> >> pixels of the DSLR are inferior compared to the higher pixel density
> >> of the small sensor camera:
>
> >>http://www.pbase.com/jps_photo/image/100092629
>
> >> --
> >> John Sheehy
>
> > It's an interesting test but it there are too many other variables
> > involved here which are causing problems. For one (and I'm not saying
> > you have the equipment, resources or money to do this test), if you
> > want to really only compare the effect of pixel density which is what
> > your subject line states, then I would think the better test is to
> > line up a 350D and 400D and a 450D - all of which have the exact same
> > sensor size, but differ in pixel density only
> > (http://www.dpreview.com/
> > reviews/compare_post.asp?method=sidebyside&cameras=canon_eos400d
> > %2Ccanon_eos450d
> > %2Ccanon_eos350d&camuser=canon_eos400d&camuser=canon_eos450d&camuser=ca
> > non_eos350d&show=all). Then you can use the exact same lens
> > etc....compare the exact same sensor size, and only worry about pixel
> > density.
>
> The pixel pitch difference between them is too small to make any
> meaningful comparison, in light of the other variables. The 450D would
> do best, and the 350D, a little worse than the 400D. Whoopedy do dah
> ding! You could write that off as incremental increases in microlens
> efficiency, minor read noise improvements, etc, as far as noise goes, and
> pixel pitch and the lack of a strong AA filter in the 450D as far as
> resolution goes. The doomsday forecast for pixel pitch, however,
> suggests that going beyond a certain point in pixel density will cause an
> increase in noise and loss of DR, but it is not happening, nowhere even
> close to current pixel densities (if ever), and that is the point of my
> demsonstration.
>
> Anyone with any amount of experience in these matters would recognize
> that even a magic lens with no softness of any kind
>
> --
>
> <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
> John P Sheehy <J...(a)no.komm>
> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><

You're saying that you could not compare the 350D to the 450D because
you might attribute the differences to things such as minor
improvements in read noise and microlens efficiencies but you CAN
compare two completely different cameras with completely different
size sensors with completely different lenses and attribute ALL of the
differences to the difference in pixel density. I was on your side
for the most part originally but sorry to say you've lost me. I just
hope you are not in science because this is NO way to run an
experiment.
From: notvalid on
On Thu, 17 Jul 2008 03:36:20 GMT, John Sheehy <JPS(a)no.komm> wrote:

>John O'Flaherty <quiasmox(a)yeeha.com> wrote in
>news:g5bs7490188ng5i849tmko3ma6aat0sh19(a)4ax.com:
>
>>>Of course, such a test would give a result already expected by almost
>>>anyone who knows anything at all about digital imaging, but would tell
>>>us absolutely nothing about the effects of pixel *density*; only about
>>>sensor size.
>
>> That clarifies it. In your post, you said that "the bigger pixels of
>> the DSLR are inferior compared to the higher pixel density of the
>> small sensor camera"; apples and orange juice.
>
>What I am demonstrating needs to be demonstrated. There is too much
>nonsense out there circulating as fact, suggesting that the more pixels
>you "stuff" into a given sensor size, the noisier the images get, the
>less DR they have, etc, etc. This clearly shows that this is not true,
>that pixels covering less of the focal plane each can currently do much
>better than big pixels, at representing the area that they are
>responsible for.
>
>This test, however, is not about DR, per se, as the 400D still has some
>more headroom than the FZ50 here. It is more about absolute sensitivity
>in this case, although the usable DR should still be better with the
>smaller pixels.

Unfortunately, there are far too many variables that have been changed
in your two test subjects to make any real conclusions about the
pixels. There is no such thing as "all things being equal" in your
tests, because virtually nothing is equal.

You have compared two test *systems* and that's all that can really be
claimed with any validity. But with that premise, I don't think that
the conclusion you're trying to form is valid. You may be able to
make quality comparisons of final printed output.... depending on how
you conduct that test (and your current testing method doesn't lend
itself to making a valid comparison of final printed output).

Data collection is a crucial part to any mathematical/statistical
analysis. And the data collection performed for this test are far too
restrictive for any statistical significance; and cannot really be
used to draw any general conclusions.

---
jls
From: Scott W on
On Jul 16, 7:20 pm, John Sheehy <J...(a)no.komm> wrote:
> Scott W <biph...(a)hotmail.com> wrote innews:381a062a-105d-4b40-92e7-08c023b59bf2(a)r66g2000hsg.googlegroups.com:
>
> > John, you should really redo the test with the ISO set higher on the
> > 400D, clearly you can also set it higher on the FZ50 as well.
>
> No, I shouldn't, because that would be a different issue altogether.  
> I've already said, many times, that the highest ISOs in some models of
> DSLRs have area-based read noise as good or slightly better than clusters
> of current P&S pixels in aggregate.  It's a given that the 400D would
> give less noise if it were set to ISO 1600.

It seems to me if you are shooting in low light conditions you would
want to have both cameras at their best setting for that. You test is
kind of like racing two cars but limited them both to third gear, even
though one car has a forth gear. If you keep the gain turn down so
low, i.e. ISO 100, you are not seeing the read noise in the 400D, you
will only see the read noise at higher ISO settings.

Scott

From: ASAAR on
On Thu, 17 Jul 2008 05:39:52 -0700 (PDT), Bates wrote:

>> <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
>> John P Sheehy <J...(a)no.komm>
>> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
>
> You're saying that you could not compare the 350D to the 450D because
> you might attribute the differences to things such as minor
> improvements in read noise and microlens efficiencies but you CAN
> compare two completely different cameras with completely different
> size sensors with completely different lenses and attribute ALL of the
> differences to the difference in pixel density. I was on your side
> for the most part originally but sorry to say you've lost me. I just
> hope you are not in science because this is NO way to run an
> experiment.

The best thing I can say for John is that he might actually believe
his own nonsense. It's ironic that he has accused others of
"cognitive dissonance" because he seems to be the one suffering most
from that affliction.

> From: John Sheehy <JPS(a)no.komm>
> Date: Thu, 17 Jul 2008 05:20:11 GMT
> Message-ID: <Xns9ADED9CD25DDjpsnokomm(a)199.45.49.11>
>
> I was one of the first people to ever notice this, and I popularized it
> here and elsewhere a few years back. That is old hat. What I am
> demonstrating here is a more advanced topic, one that causes a lot of
> cognitive dissonance in people with pixel-centric imaging philosophies.

When people here recently saw DPReview's article demonstrating
sensor noise and detail at high ISOs, only one person disagreed with
the obvious demonstration that the best performer by a wide margin
(after Canon's DSLR ringer) was Fuji's F30. Panasonic's FZ-50 was
included in the comparison and it didn't do well at all. This
shouldn't have been surprising given that it stuffed nearly twice as
many pixels into a sensor smaller than the one used by Fuji's F30.
Sheehy insisted that the FZ-50 produced more detail even though it
the F30 produced clearly legible text in its images where the FZ-50
rendered the text as totally unreadable fuzzy blobs, and resorted to
a grossly unscientific description of the F30's images as (IIRC)
plastic and cartoonish.

If the FZ-50 really has some kind of noise advantage at ISO 100
over Canon's DLSR it would be useful if he could demonstrate it
using real images, and to the extent possible, with both cameras
filling their sensors with the same image. You might want to take
portraits where a person's face fills the frame and then compare
greatly enlarged crops.

What Sheehy has done instead is to compare portions of each sensor
having the same actual area. The 5D stores 12.8mp in a sensor that
is 22.4 times larger than the FZ-50's 10.1mp sensor. So the largest
part of the 5D's sensor that could be compared would contain only
0.571mp (if compared against the FZ-50's entire sensor). It really
is ludicrous to design a test where more than 95% of the light
reaching the DSLR's sensor is discarded, while proclaiming that this
is a fair test designed to keep things equal. But then, Sheehy owns
an FZ-50 which is known to have very poor high ISO performance. And
despite his claim that implies otherwise :

> People actually believe that the noise of a pixel is the noise of an
> image; that the DR of a pixel is the DR of an image.

he seems to want to show that his FZ-50 is desirable by examining
the noise and DR of a pixel, while the rest of the world judges the
worth of their cameras by the noise and DR of the images they
produce.


> rfischer(a)sonic.net (Ray Fischer) wrote in news:487d881a$0$17222
> $742ec2ed(a)news.sonic.net:
>
>> John P Sheehy <jps(a)no.kom> wrote:
>> . . .
>> In other words, if you know what results you want to get then you can
>> adjust your measurement to get those results.
> . . .
> If you think that this is some juvenile praise of the FZ50, you are a blunt
> idiot, on a witch hunt for fanboys.

Extra! Extra! Blunt idiot makes a fool of flaming fanboy!

:)

From: Paul Furman on
John Sheehy wrote:
>
> What I am demonstrating needs to be demonstrated. There is too much
> nonsense out there circulating as fact, suggesting that the more pixels
> you "stuff" into a given sensor size, the noisier the images get, the
> less DR they have, etc, etc. This clearly shows that this is not true,
> that pixels covering less of the focal plane each can currently do much
> better than big pixels, at representing the area that they are
> responsible for.
>
> This test, however, is not about DR, per se, as the 400D still has some
> more headroom than the FZ50 here. It is more about absolute sensitivity
> in this case, although the usable DR should still be better with the
> smaller pixels.

'Usable DR'?

--
Paul Furman
www.edgehill.net
www.baynatives.com

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