From: David J. Littleboy on

"Jufi" <bowser(a)work.com> wrote:
> "John Sheehy" <JPS(a)no.komm> wrote in message
> news:Xns9ADCEBDB1EE43jpsnokomm(a)199.45.49.11...
>> Juf� <b0wser(a)h0me.c0m> wrote in news:Zhbfk.265$av4.11(a)trnddc04:
>>
>>> John, nothing you've posted here is correct. If you want, I'll shoot
>>> pix using my G9 and 5D at ISO 1600, and post the 100% crops.
>>> Resolution of the sensors is very close, only the size of the pixels
>>> is very different. It will shot that smaller pixels simply cannot
>>> compete with larger pixels. Unless I'm totally missing your point
>>> here...
>>
>> Yes, you are totally missing the point here. The demonstration is of
>> PIXEL
>> DENSITY; not SENSOR SIZE; not PIXEL SIZE.
>
> Uh, OK. So why not compare cameras with the same size sensors but
> different numbers of pixels?

That would make it too easy. Which would you rather have: a D70 or a D300?

--
David J. Littleboy
Tokyo, Japan


From: John O'Flaherty on
On Wed, 16 Jul 2008 03:00:50 GMT, John Sheehy <JPS(a)no.komm> wrote:

>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.

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.
--
John
From: Paul Furman on
Blinky the Shark wrote:
> John Sheehy wrote:
>
>> Scott W <biphoto(a)hotmail.com> wrote in
>> news:fbef99b9-2adc-429e-96bc-9f46ec665b7f(a)x41g2000hsb.googlegroups.com:
>>
>>> Do we really need more cross posting?
>> I generally don't mind relevant cross-posting, but that comes from using
>> Agent. I am using XNews now, and the method of cross-post management in
>> XNews seems a bit inferior and dangerous, so I wind up seeing a lot of
>> things twice.
>
> Then you don't know how to use Xnews.

With Thunderbird I save the thread in the first group in the list &
manually mark the rest as ignored.

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

all google groups messages filtered due to spam
From: Paul Furman on
Roger N. Clark (change username to rnclark) 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
>>
> Hello,
> Someone asked me to comment, so...
>
> John, here is why the test is not equal and biased in favor of the
> small pixel camera: the gain and noise in the electronics. The FZ50
> at ISO 100 is operating at about 2x unity gain. The 400D is operating
> so far below unity gain so that noise from the A/D converter is the
> limiting
> factor. Try your test again with the 400D at similar 2x unity gain
> (ISO 1600 should do). That way the noise in both images will be
> dominated by photon noise and sensor read noise, not post sensor
> electronics.
>
> <snipped>
>
> But John does have a point about more pixels can be better. As pixel
> size drops, so does dynamic range. You can't have more dynamic range than
> the total number of photons you collect per pixel. The FZ50, for example,
> collects a max between 1,000 and 2,000 photons, whereas the 400D
> over 40,000. That's 20 times the highlight room! (We do need better
> A/D converters in these cameras, as they currently are the limiting factor
> in dynamic range and low signals at low ISO).

Thanks Roger!

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

all google groups messages filtered due to spam
From: Scott W on
On Jul 15, 5:22 pm, "Roger N. Clark (change username to rnclark)"
<usern...(a)qwest.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
>
> Hello,
> Someone asked me to comment, so...
>
> John, here is why the test is not equal and biased in favor of the
> small pixel camera: the gain and noise in the electronics.  The FZ50
> at ISO 100 is operating at about 2x unity gain.  The 400D is operating
> so far below unity gain so that noise from the A/D converter is the limiting
> factor.  Try your test again with the 400D at similar 2x unity gain
> (ISO 1600 should do).  That way the noise in both images will be
> dominated by photon noise and sensor read noise, not post sensor electronics.

Good points Roger,

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.

I know in tests i have done shooting at higher iso, when using the
same shutter speed and f/stop, reduces the noise by a lot, you can see
the test images here
http://www.pbase.com/konascott/image/71375911
All 5 images were taken at f/11 and 1/30 sec.

It would also be interesting to see the image from the FZ50 reduced in
size to match the 400D, as well as the other way around.

Scott