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Canon S70: aggressive noise reduction?

 
 
Iris Nadine Kartasasmita
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      03-22-2005
Hi folks,

I'm trying to figure out when really the Canon S70 noise reduction starts to
reduce the quality of the photo. I've taken 2 similar pictures, one with (a)
f2.8 - 1/60s and the other one with (b) f8 - 1/6s. The quality of picture
(b) is noticeably less than (a); and I believe this is due to the noise
reduction (see http://home.unet.nl/irisnadine/s70.jpg - taken with tripod!).

Has anybody similar experience with this....?

iris


 
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David J Taylor
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      03-22-2005
Iris Nadine Kartasasmita wrote:
> Hi folks,
>
> I'm trying to figure out when really the Canon S70 noise reduction
> starts to reduce the quality of the photo. I've taken 2 similar
> pictures, one with (a) f2.8 - 1/60s and the other one with (b) f8 -
> 1/6s. The quality of picture (b) is noticeably less than (a); and I
> believe this is due to the noise reduction (see
> http://home.unet.nl/irisnadine/s70.jpg - taken with tripod!).
>
> Has anybody similar experience with this....?
>
> iris


To me, the 1/6s image looks as if either it is out of focus, or your are
seeing the diffraction effects due to the very small aperture. By noise
reduction, do you mean some filtering of the image, or dark frame
subtraction?

David


 
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C J Campbell
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      03-23-2005

"Iris Nadine Kartasasmita" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi folks,
>
> I'm trying to figure out when really the Canon S70 noise reduction starts

to
> reduce the quality of the photo.


Noise reduction always reduces the quality of the photo. Shoot in raw if you
can and control the amount of noise reduction in post processing.


 
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Iris Nadine Kartasasmita
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      03-23-2005

"David J Taylor" <(E-Mail Removed)-this-bit.nor-this-part.uk>
schreef in bericht news:TVY%d.3342$(E-Mail Removed). ..
> Iris Nadine Kartasasmita wrote:
> > Hi folks,
> >
> > I'm trying to figure out when really the Canon S70 noise reduction
> > starts to reduce the quality of the photo. I've taken 2 similar
> > pictures, one with (a) f2.8 - 1/60s and the other one with (b) f8 -
> > 1/6s. The quality of picture (b) is noticeably less than (a); and I
> > believe this is due to the noise reduction (see
> > http://home.unet.nl/irisnadine/s70.jpg - taken with tripod!).
> >
> > Has anybody similar experience with this....?
> >
> > iris

>
> To me, the 1/6s image looks as if either it is out of focus, or your are
> seeing the diffraction effects due to the very small aperture. By noise
> reduction, do you mean some filtering of the image, or dark frame
> subtraction?
>
> David
>


David, I think it is not due to out of focus (at least I left it on "auto"
mode
for focusing). And I got a similar "softness" effect when I took landscape
photo at dawn (with tripod, slow shutter speed). I saw in one of the
review on http://www.imaging-resource.com/PRODS/CS70/S70P.HTM
".... Namely, the impact that anti-noise processing has on subtle subject
detail. The G6 and S70 both use the same CCD chip (and I believe the Sony
P150 does as well), so the slightly lower noise levels shown in the chart
above for the S70 have to come from more aggressive anti-noise processing.
This in fact appears to be the case, as I found that the S70 had a slightly
greater tendency to flatten-out subject detail in areas of subtle contrast
than did the G6......"

What I see with many of the photos taken with slow shutter speed
(and small aperture) are not as sharp as photos taken with
large aperture (hence fast shutter speed).

iris


 
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Iris Nadine Kartasasmita
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      03-23-2005

"C J Campbell" <(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed)...
>
> "Iris Nadine Kartasasmita" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > Hi folks,
> >
> > I'm trying to figure out when really the Canon S70 noise reduction

starts
> to
> > reduce the quality of the photo.

>
> Noise reduction always reduces the quality of the photo. Shoot in raw if

you
> can and control the amount of noise reduction in post processing.
>
>


I thought so too.... That is what I took test photos in raw mode... Still
the
result is the same (see mail original post). Could it be due to the lens?


 
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T.N.T.
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      03-24-2005
On Tue, 22 Mar 2005 17:37:45 GMT, "Iris Nadine Kartasasmita"
<(E-Mail Removed)>, wrote in news:(E-Mail Removed):

> Hi folks,
>
> I'm trying to figure out when really the Canon S70 noise reduction
> starts to reduce the quality of the photo. I've taken 2 similar
> pictures, one with (a) f2.8 - 1/60s and the other one with (b) f8 -
> 1/6s. The quality of picture (b) is noticeably less than (a); and I
> believe this is due to the noise reduction (see
> http://home.unet.nl/irisnadine/s70.jpg - taken with tripod!).
>


It's diffraction effect. f/8 is too small for lenses designed to cover
1/1.8" or 2/3". All small size sensor digicams has this problem.

As to the S70 specifically, I believe it has 2 types of noise reduction.
One is the dark frame NR, usually applied when the shutter speed is 1
second or slower on Canon cameras. This one only served to remove the hot
pixel effects and I believe it would not remove small details on the
image.

The second one is software/firmware NR, usualy used to reduce high noise
in dark area or in high ISO images. This one will affect image quality.
But if you shoot RAW, depending on software, you can freely choose to
apply NR or not. You can test this NR effect by shooting two dark
pictures or use high ISO, one shot in JPG, the other in RAW format then
compare the results.


--
T.N.T.

Lbh xabj jung gb qb vs lbh rire jnag gb rznvy zr.
 
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Iris Nadine Kartasasmita
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      03-24-2005

> It's diffraction effect. f/8 is too small for lenses designed to cover
> 1/1.8" or 2/3". All small size sensor digicams has this problem.


T.N.T., does it mean that I should better take picture with the largest
aperture for this kind of camera? Is there a "rule of thumb" for guessing
the smallest useful aperture (depth of field vs. diffraction)? Looking with
the test I've done, it seems f/5.6 is the limit...

iris.


 
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