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ISO ?? on a digital cam.

 
 
orion
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      05-21-2004
Many digitals have ISO selection. I obviously know from SLR's what to
expect, ie increase the ISO of a film generally equals more noise and
grain..

What's the effect of a decent digital of using a higher ISO? Does the
digital noise increase?, and to what extent, (more or less than film)?


 
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Lionel
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      05-21-2004
Kibo informs me that "orion" <(E-Mail Removed)> stated that:

> Many digitals have ISO selection. I obviously know from SLR's what to
>expect, ie increase the ISO of a film generally equals more noise and
>grain..
>
>What's the effect of a decent digital of using a higher ISO?


It's fairly similar to the same thing with film, although digital noise
doesn't look the same as heavy grain.

> Does the
>digital noise increase?,


Yes.

> and to what extent, (more or less than film)?


Depends on the camera. Digicams tend to be worse than film at higher
ISO's, & the nicer DSLRs tend to be better.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
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Banjopikr1
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      05-21-2004
>What's the effect of a decent digital of using a higher ISO? Does the
>digital noise increase?,


Depends on the sensor in the camera. CMOS sensors have less noise than the CCD
sensors. I use ISO 800 frequently on a digital rebel and the noise is almost
non existent. At ISO 1600, some noise shows, but generally acceptable. The
newer CCD cameras are much better now.
 
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DJ
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      05-21-2004
On Fri, 21 May 2004 08:06:19 GMT, "orion" <(E-Mail Removed)> wrote:

> Many digitals have ISO selection. I obviously know from SLR's what to
>expect, ie increase the ISO of a film generally equals more noise and
>grain..
>
>What's the effect of a decent digital of using a higher ISO? Does the
>digital noise increase?, and to what extent, (more or less than film)?
>


If you have broadband, here are some large sample files

ISO100 http://www.splatco.com/david/red_rose.jpg 500K

ISO1600 http://www.splatco.com/david/a_flower_for_george.jpg 2+MB


In each case, in IE they will display small and and need to be enlarged: hover
the mouse and click the button that appear in the lower RH corner.

Both taken with a Canon 300D.

The ISO 1600 pic was taken as a dare for the group's resident troll/fruitcake.
I'd not normally use 1600 ISO on such a subject, but it demonstrates that 1600
is emminently useable in these cameras.

Note you would not get anywhere near comparable results with one of the "lesser"
point and shoot digitals. They use tiny sensors and suffer horrific noise at
high sensitivities. Just look for some Sony F828 samples to see what I mean.


 
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Ken Anderson
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      05-21-2004
"DJ" <(E-Mail Removed)> wrote
>
> In each case, in IE they will display small and and need to be enlarged:

hover
> the mouse and click the button that appear in the lower RH corner.
>
>

You can fix that in Tools, Internet Options, Advanced. Scroll down to the
Multimedia section and uncheck "Enable Automatic Image Resizing."


 
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Alan Browne
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      05-21-2004
orion wrote:

> Many digitals have ISO selection. I obviously know from SLR's what to
> expect, ie increase the ISO of a film generally equals more noise and
> grain..
>
> What's the effect of a decent digital of using a higher ISO? Does the
> digital noise increase?, and to what extent, (more or less than film)?


You've got the right idea. When film spped increases, the grain size
increases (in x,y if you will). But for digital, the noise increases
(dynamic) without changing in x,y dimension. Good DSLR's look quite
noise free until high ISO / high reproduction sizes are made.


--
--e-meil: there's no such thing as a FreeLunch.--

 
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Don
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      05-21-2004
"orion" <(E-Mail Removed)> wrote in message
news:%Lirc.834$(E-Mail Removed)...
> Many digitals have ISO selection. I obviously know from SLR's what to
> expect, ie increase the ISO of a film generally equals more noise and
> grain..
>
> What's the effect of a decent digital of using a higher ISO? Does the
> digital noise increase?, and to what extent, (more or less than film)?
>
>

The ISO rating of film is a measure of the film's sensitivity to light. It
is not a measure of the granularity. The measurement technique takes into
account the "toe" characteristics of the film, a phenomenon that does not
exist in CCD or CMOS focal planes. The last I heard the ISO were attempting
to standardize on a rating for digital systems, but had not yet published a
draft.

We are used to relating the ISO rating of a film to its granularity because,
in fact, they are related through the detective quantum efficiency (DQE) of
the film, which is relatively stationary from film to film but has improved
over the years. It's difficult to measure, but in modern B&W films it's in
the region of 1%-2%, I believe. In color films it's even more difficult to
measure, and is different for each layer. It's usually taken to be in the
region of 0.8% to 1.5%, but I don't think anyone is very confident in that.

While the DQE of CCDs is much higher, as much as 90% in linear B&W arrays,
there are other noise sources that usually predominate over the photon
noise. These include leakage current, preamplifier noise, discharge current
noise, etc.

The ISO rating of films within a given family is controlled by the grain
size. For a constant DQE, the granularity goes up with the square root of
the ISO rating, more or less. The variablity of speed of a CCD is
controlled by the gain of the preamplifier and A-to-D converter. Because
the extraneous noise sources predominate over the photon noise, the noise
goes up more or less proportional to the speed. That's why most digital
cameras that look good at ISOs of 50-100 seem to fall behind their film
counterparts at the higher ISO ratings.

Don




 
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George Preddy
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      05-22-2004
Lionel <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>. ..

> It's fairly similar to the same thing with film, although digital noise
> doesn't look the same as heavy grain.


This depends on the design. Foveon noise at very high ISOs looks just
like high ISO film grain so their is basically no penalty from using
film. Bayer noise is comprised of brilliant multi-colored artifacts
than make for a real obviously-taken-with-digital mess, see...

http://www.dpreview.com/reviews/sigmasd10/page13.asp
 
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Lionel
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      05-22-2004
Kibo informs me that http://www.velocityreviews.com/forums/(E-Mail Removed) (George Preddy) stated
that:

>Lionel <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>. ..
>
>> It's fairly similar to the same thing with film, although digital noise
>> doesn't look the same as heavy grain.

>
>This depends on the design. Foveon noise at very high ISOs lo[*SLAP!*]


The SD9 doesn't even *have* high ISO settings.

We're still waiting to see those photos you lied about selling,
'George'.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
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Bart van der Wolf
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      05-23-2004

"George Preddy" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Lionel <(E-Mail Removed)> wrote in message

news:<(E-Mail Removed)>. ..
>
> > It's fairly similar to the same thing with film, although digital noise
> > doesn't look the same as heavy grain.

>
> This depends on the design. Foveon noise at very high ISOs looks just
> like high ISO film grain so their is basically no penalty from using
> film. Bayer noise is comprised of brilliant multi-colored artifacts
> than make for a real obviously-taken-with-digital mess, see...
>

Similar luminance noise:
<http://www.dpreview.com/reviews/SigmaSD10/Samples/ISO/lumi_graph.gif>

Bart

 
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