From: Richard on
Since you didn't post this on the DSLR group, I've re-directed it there for
you. :)

"John P Sheehy" <jps(a)no.kom> wrote in message
news:Xns9ADC5F5E96172jpsnokom(a)199.45.49.11...
> 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


From: Scott W on
On Jul 15, 3:50 pm, "Richard" <rander3...(a)gmail.com> wrote:
> Since you didn't post this on the DSLR group, I've re-directed it there for
> you.  :)
>
> "John P Sheehy" <j...(a)no.kom> wrote in messagenews:Xns9ADC5F5E96172jpsnokom(a)199.45.49.11...
>
>
>
> > 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
>

Do we really need more cross posting?

Scott

From: Richard on
Notice that I can buy a lens from a scientific supplier that specifies
exactly what lp/mm (like 100 maybe?) I'll get with say 5um pixels, but NONE
of the consumer mfgs will provide that kind of data for their lenses? It
can only be derived by testing.
http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2688

"Scott W" <biphoto(a)hotmail.com> wrote in message
news:43151e3e-dc72-428a-aeea-636f091a3d0c(a)56g2000hsm.googlegroups.com...
On Jul 15, 8:45 am, Paul Furman <pa...@-edgehill.net> wrote:
> John P Sheehy 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
>
> Of course, the DSLR image is enlarged more than 3x!
>
> 7.18 x 5.32 mm
> 24 x 18 mm

The test is interesting but some thought is needed to interpret what
it means. If you had a really good lens on the DSLR and had 1.97
micron pixels across the same size sensor area then you might get
improved results over the larger pixels. This would require a pretty
good lens however, past what most lenses 35mm lenses will produce.

Given the limits of the current lenses we start to get to diminishing
returns for more pixels on the same size sensor. It seems that going
much below 4-5 microns for the current 35mm lenses does not make a lot
of sense.

Of course there is nothing to stop someone for designing a large
sensor with 2 micron pixels and designing a new set of lenses to go
with it, but the cost of a lens starts to go up fast as it is required
to resolve smaller pixels. IN the case of the FZ50, its lens covers
a much smaller image circle then the 400D, so you could not simple use
this lens on a larger sensor camera.

If we are just looking at whether small pixels or large pixels are
better, given a fixed number of them, then the test photos should
really cover the same field of view rather then having the same FL.

My conclusion is that there is a potential for improved images with
more pixels, but to realize this potential we need better lenses.

Scott


The test is interesting but some thought is needed to interpert what
it means.


From: John Sheehy on
"Richard" <rander3127(a)gmail.com> wrote in
news:udCdnfTLKrdVyuDVnZ2dnUVZ8tLinZ2d(a)giganews.com:

> Notice that I can buy a lens from a scientific supplier that specifies
> exactly what lp/mm (like 100 maybe?) I'll get with say 5um pixels, but
> NONE of the consumer mfgs will provide that kind of data for their
> lenses? It can only be derived by testing.

I've used lenses I own on 8 and 10 MP APS DSLRs with stacks of TCs of 2.8x,
and 4x, and gotten detail that was fragile enough to get lost downsampling
to 70%. This means that these lenses should enjoy 8x to 16x the pixel
density, without the TCs.

--

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John P Sheehy <JPS(a)no.komm>
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From: John Sheehy on
John O'Flaherty <quiasmox(a)yeeha.com> wrote in
news:gtfq745k791rftrgcudhrl64595vg99p99(a)4ax.com:

> What happens if you compare subimages using the same number of pixels
> to cover the same subject area, with, say, the same total illumination
> falling on that subject area?

Then the 400D would clearly be better, noise-wise, with about 60% the read
noise of the FZ50, and about 4x as many photons collected. Optically, the
comparison would depend on what lens was on the 400D.

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.

--

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John P Sheehy <JPS(a)no.komm>
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