From: John Sheehy on
"Pat" <groups(a)artisticphotography.us> wrote in
news:1173978631.076844.287690(a)e1g2000hsg.googlegroups.com:


> At the risk of pissing off all of the "purists" out there, you might
> want to consider the original Canon Digital Rebel (the good old 300).
> That would get you a useable body for not much money. Then add the
> Russian operating system to get to ISO of 3200. It's a bit grainy but
> sometimes grainy is better than nothing.

ISO 3200 on the 10D and the 300D with the hack is nothing but ISO 1600
metered for a stop of under-exposure.

The 10D and 300D are worse performers at high ISO than any of the APS-sized
Canon DSLRs to come after them. The 10D/300D have about 4x the read noise
in the deepest shadows as the 20D and 30D and more than 2x the XTi pushed
to 3200.

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John P Sheehy <JPS(a)no.komm>
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From: John Sheehy on
"acl" <achilleaslazarides(a)yahoo.co.uk> wrote in
news:1173975897.845961.131720(a)e65g2000hsc.googlegroups.com:

> On Mar 15, 2:31 pm, John Sheehy <J...(a)no.komm> wrote:
>> that standard deviation is only *one* factor in the noise equation;
>> magnification is another, and the low noise of big pixels is visually
>> magnified when the pixels are magnified along with the subject.
>
> Exactly, and if you don't need the extra pixels you can bin.

Yes, but I think it is very important to stress that there is no need to
bin to get the benefit. Often, the situation is described in such a way
that binning or downsampling are *necessary* to get the benefit. There
is a cult of pixel-for-pixel's sake that misses the forest (image or
subject) for the trees (pixels), IMO. To me, the most important quality
factors in descending importance are:

1) SQ (subject quality)

2) IQ (image quality)

3) PQ (pixel quality)

If #3 doesn't also help #1, it is in vein.

>> 2) slight benefit in photons collection rate per unit of sensor area
>> due
>> to less wasted space on the sensor (not always realized, however; my
>> 1.97u FZ50, for example, collects about the same number of photons per
>> unit of area as the 1DmkII, at RAW saturation for the same ISO).

> Well, as long as there are no constant noise sources (eg 10 electrons/
> pixel independent of the area). I have no idea if there are or not.

Blackframe read noise on my FZ50 is about 3.34 electrons at ISO 100 (4800
electrons at saturation), and about 2.71 electrons at ISO 1600 (about 300
electrons at saturation). Binned down 3x3 (to DSLR size), that's about
0.9 and 1.11 electrons (43,200 and 2700 max), respectively.

These values are derived from multiplying the standard deviation of FZ50
blackframes by 1.66, since the Panasonic RAW files, unfortunately, are
clipped at the blackpoint, a very bad idea that most camera manufacturers
engage in. Canon is one of the few that leave a bias in the RAW data
with a full symmetrical noise histogram with positive and negative noise.
Clipping at black means bright, noise-clouded blacks with minute signals
clipped. Blackpoint clipping should not occur, IMO, until your RAW
conversion needs to enter a gamma-adjusted state (where negative signal
or noise are meaningless). All white-balancing, resampling, and
demosaicing should be done before the clipping, to maintain black blacks,
and a minimum of noise. I would guess that most converters don't
maintain this state, but clip Canons at black immediately upon loading
RAW data to get it in the same state as most other cameras. In my own
hand-conversions in IRIS and in PS with filtermeister and RAW linear
greyscale sources, I have made conversions with much less color tint and
bright haze in the deepest shadows. In fact, I have even promoted images
to a higher bit-depth before any interpolative actions, for more
precision. RAW converters, generally, are taking a lot of short-cuts,
IMO, and are not delivering what they can in these areas. They seem
focused mainly on the post-processing values like skin color and tonal
curves in the highlight areas, etc.

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John P Sheehy <JPS(a)no.komm>
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From: acl on
On Mar 16, 3:55 pm, "David J. Littleboy" <davi...(a)gol.com> wrote:
> "acl" <achilleaslazari...(a)yahoo.co.uk> wrote:
> > On Mar 16, 6:29 am, "David J. Littleboy" <davi...(a)gol.com> wrote:
>
> >> I think you guys are talking past each other here.
>
> >> I think John is arguing that _for a sensor of a given size_, larger
> >> pixels
> >> aren't any better.
>
> > But doesn't this make him a "crop fan" for you?
>
> 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.

Well Roger's argument is that read noise is independent of pixel size,
in which case there is a pixel size that optimizes the resolution/
noise tradeoff (it depends on where you set your threshold for noise
tolerance and on the noise properties of the sensor and electronics).

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. But it
seems that now, for some reason, you decided to think before
ridiculing, and I was forced to conclude that it has to do with the
messenger rather than the message.

From: Pat on
On Mar 16, 12:15 pm, John Sheehy <J...(a)no.komm> wrote:
> "Pat" <gro...(a)artisticphotography.us> wrote innews:1173978631.076844.287690(a)e1g2000hsg.googlegroups.com:
>
> > At the risk of pissing off all of the "purists" out there, you might
> > want to consider the original Canon Digital Rebel (the good old 300).
> > That would get you a useable body for not much money. Then add the
> > Russian operating system to get to ISO of 3200. It's a bit grainy but
> > sometimes grainy is better than nothing.
>
> ISO 3200 on the 10D and the 300D with the hack is nothing but ISO 1600
> metered for a stop of under-exposure.
>
> The 10D and 300D are worse performers at high ISO than any of the APS-sized
> Canon DSLRs to come after them. The 10D/300D have about 4x the read noise
> in the deepest shadows as the 20D and 30D and more than 2x the XTi pushed
> to 3200.
>
> --
>
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> John P Sheehy <J...(a)no.komm>
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Yeah, and .....

The OP's best bet would be a Hasselblad, a few banks of soft boxes,
and a crew of gaffers. But, like your ideas, it doesn't take into
account the OP's budget. You want to start with a $1200 camera when
the persons budget is $1000. Ain't going to happen.

So if you don't like my idea -- which I'm not sure I even like my idea
-- what dSLR would you suggest for the OP with a $1000 budget (don't
forget sales tax and shipping)?

From: John Sheehy on
"Pat" <groups(a)artisticphotography.us> wrote in
news:1174068774.683691.273470(a)n59g2000hsh.googlegroups.com:

> So if you don't like my idea -- which I'm not sure I even like my idea
> -- what dSLR would you suggest for the OP with a $1000 budget (don't
> forget sales tax and shipping)?

A used 20D or a used Rebel XT.

With lenses, might run a little bit more than a used 300D, but will be far
faster in operation, and better in low light. Sometimes it's worth going a
little over budget to get something a notch or two better.

--

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