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New Canon 350D/Rebel XT Noise Tests

 
 
wayne
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      05-11-2006
Hi All,

I've placed two articles looking at 350D/Rebel XT image noise in
daytime and nighttime shooting up on DIMi
<http://www.dimagemaker.com/article.php?articleID=531> and placed all
the RAW files for people to download and examine themselves if they are
interested <http://www.dimagemaker.com/specials/cameras/camtests.php>

Cheers,

Wayne

Wayne J. Cosshall
Publisher, The Digital ImageMaker, http://www.dimagemaker.com/
Blog and Podcast http://www.digitalimagemakerworld.com/
Personal art site http://www.artinyourface.com/

 
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Kevin McMurtrie
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      05-11-2006
In article <(E-Mail Removed) .com>,
"wayne" <(E-Mail Removed)> wrote:

> Hi All,
>
> I've placed two articles looking at 350D/Rebel XT image noise in
> daytime and nighttime shooting up on DIMi
> <http://www.dimagemaker.com/article.php?articleID=531> and placed all
> the RAW files for people to download and examine themselves if they are
> interested <http://www.dimagemaker.com/specials/cameras/camtests.php>
>
> Cheers,
>
> Wayne
>
> Wayne J. Cosshall
> Publisher, The Digital ImageMaker, http://www.dimagemaker.com/
> Blog and Podcast http://www.digitalimagemakerworld.com/
> Personal art site http://www.artinyourface.com/


The noise reduction option is for hot pixels only. It's useful for very
long exposures, say over 10 minutes.

The Canon DSLRs have noise reduction built into the sensor that
compensates for stray charge offsets in each pixel. You can't turn it
off. There's also some software noise reduction if you use Canon's
software to convert the RAW file.
 
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alex
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Posts: n/a
 
      05-11-2006

"Kevin McMurtrie" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)-sjc.supernews.net...
> In article <(E-Mail Removed) .com>,
> "wayne" <(E-Mail Removed)> wrote:
>
>> Hi All,
>>
>> I've placed two articles looking at 350D/Rebel XT image noise in
>> daytime and nighttime shooting up on DIMi
>> <http://www.dimagemaker.com/article.php?articleID=531> and placed all
>> the RAW files for people to download and examine themselves if they are
>> interested <http://www.dimagemaker.com/specials/cameras/camtests.php>
>>
>> Cheers,
>>
>> Wayne
>>
>> Wayne J. Cosshall
>> Publisher, The Digital ImageMaker, http://www.dimagemaker.com/
>> Blog and Podcast http://www.digitalimagemakerworld.com/
>> Personal art site http://www.artinyourface.com/

>
> The noise reduction option is for hot pixels only. It's useful for very
> long exposures, say over 10 minutes.
>
> The Canon DSLRs have noise reduction built into the sensor that
> compensates for stray charge offsets in each pixel. You can't turn it
> off. There's also some software noise reduction if you use Canon's
> software to convert the RAW file.


My 350D has a long exposure noice reduction - Custom Function 2 in the menu
on P A S / M modes.

Alex


 
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Kevin McMurtrie
Guest
Posts: n/a
 
      05-11-2006
In article <(E-Mail Removed)>,
"alex" <(E-Mail Removed)> wrote:

> "Kevin McMurtrie" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)-sjc.supernews.net...
> > In article <(E-Mail Removed) .com>,
> > "wayne" <(E-Mail Removed)> wrote:
> >
> >> Hi All,
> >>
> >> I've placed two articles looking at 350D/Rebel XT image noise in
> >> daytime and nighttime shooting up on DIMi
> >> <http://www.dimagemaker.com/article.php?articleID=531> and placed all
> >> the RAW files for people to download and examine themselves if they are
> >> interested <http://www.dimagemaker.com/specials/cameras/camtests.php>
> >>
> >> Cheers,
> >>
> >> Wayne
> >>
> >> Wayne J. Cosshall
> >> Publisher, The Digital ImageMaker, http://www.dimagemaker.com/
> >> Blog and Podcast http://www.digitalimagemakerworld.com/
> >> Personal art site http://www.artinyourface.com/

> >
> > The noise reduction option is for hot pixels only. It's useful for very
> > long exposures, say over 10 minutes.
> >
> > The Canon DSLRs have noise reduction built into the sensor that
> > compensates for stray charge offsets in each pixel. You can't turn it
> > off. There's also some software noise reduction if you use Canon's
> > software to convert the RAW file.

>
> My 350D has a long exposure noice reduction - Custom Function 2 in the menu
> on P A S / M modes.
>
> Alex


Yes, that's dark frame subtraction. It activates when the exposure is
>=30 seconds at ISO 100-800 or >=1 second at ISO 1600. A second photo

will be taken with the shutter closed.

NR is best left turned off until your exposures are long enough to
develop hot pixel problems. That can be over 10 minutes for some
Canons. The dark frame subtraction process can slightly damage a photo
by subtracting dynamic noise that doesn't correlate to noise in the
photo taken.
 
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alex
Guest
Posts: n/a
 
      05-11-2006

"Kevin McMurtrie" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)-sjc.supernews.net...
> In article <(E-Mail Removed)>,
> "alex" <(E-Mail Removed)> wrote:
>
>> "Kevin McMurtrie" <(E-Mail Removed)> wrote in message
>> news:(E-Mail Removed)-sjc.supernews.net...
>> > In article <(E-Mail Removed) .com>,
>> > "wayne" <(E-Mail Removed)> wrote:
>> >
>> >> Hi All,
>> >>
>> >> I've placed two articles looking at 350D/Rebel XT image noise in
>> >> daytime and nighttime shooting up on DIMi
>> >> <http://www.dimagemaker.com/article.php?articleID=531> and placed all
>> >> the RAW files for people to download and examine themselves if they
>> >> are
>> >> interested <http://www.dimagemaker.com/specials/cameras/camtests.php>
>> >>
>> >> Cheers,
>> >>
>> >> Wayne
>> >>
>> >> Wayne J. Cosshall
>> >> Publisher, The Digital ImageMaker, http://www.dimagemaker.com/
>> >> Blog and Podcast http://www.digitalimagemakerworld.com/
>> >> Personal art site http://www.artinyourface.com/
>> >
>> > The noise reduction option is for hot pixels only. It's useful for
>> > very
>> > long exposures, say over 10 minutes.
>> >
>> > The Canon DSLRs have noise reduction built into the sensor that
>> > compensates for stray charge offsets in each pixel. You can't turn it
>> > off. There's also some software noise reduction if you use Canon's
>> > software to convert the RAW file.

>>
>> My 350D has a long exposure noice reduction - Custom Function 2 in the
>> menu
>> on P A S / M modes.
>>
>> Alex

>
> Yes, that's dark frame subtraction. It activates when the exposure is
>>=30 seconds at ISO 100-800 or >=1 second at ISO 1600. A second photo

> will be taken with the shutter closed.
>
> NR is best left turned off until your exposures are long enough to
> develop hot pixel problems. That can be over 10 minutes for some
> Canons. The dark frame subtraction process can slightly damage a photo
> by subtracting dynamic noise that doesn't correlate to noise in the
> photo taken.


Kevin,

If I switch it on, does is stay inactive as long as exposures are < 30secs?

Am I better off doing this in Paintshop/Photoshop? or is it worthwhile when
the circumstances call for it?

Cheers

Alex


 
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Kevin McMurtrie
Guest
Posts: n/a
 
      05-12-2006
In article <(E-Mail Removed)>,
"alex" <(E-Mail Removed)> wrote:

> "Kevin McMurtrie" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)-sjc.supernews.net...
> > In article <(E-Mail Removed)>,
> > "alex" <(E-Mail Removed)> wrote:
> >
> >> "Kevin McMurtrie" <(E-Mail Removed)> wrote in message
> >> news:(E-Mail Removed)-sjc.supernews.net...
> >> > In article <(E-Mail Removed) .com>,
> >> > "wayne" <(E-Mail Removed)> wrote:
> >> >
> >> >> Hi All,
> >> >>
> >> >> I've placed two articles looking at 350D/Rebel XT image noise in
> >> >> daytime and nighttime shooting up on DIMi
> >> >> <http://www.dimagemaker.com/article.php?articleID=531> and placed all
> >> >> the RAW files for people to download and examine themselves if they
> >> >> are
> >> >> interested <http://www.dimagemaker.com/specials/cameras/camtests.php>
> >> >>
> >> >> Cheers,
> >> >>
> >> >> Wayne
> >> >>
> >> >> Wayne J. Cosshall
> >> >> Publisher, The Digital ImageMaker, http://www.dimagemaker.com/
> >> >> Blog and Podcast http://www.digitalimagemakerworld.com/
> >> >> Personal art site http://www.artinyourface.com/
> >> >
> >> > The noise reduction option is for hot pixels only. It's useful for
> >> > very
> >> > long exposures, say over 10 minutes.
> >> >
> >> > The Canon DSLRs have noise reduction built into the sensor that
> >> > compensates for stray charge offsets in each pixel. You can't turn it
> >> > off. There's also some software noise reduction if you use Canon's
> >> > software to convert the RAW file.
> >>
> >> My 350D has a long exposure noice reduction - Custom Function 2 in the
> >> menu
> >> on P A S / M modes.
> >>
> >> Alex

> >
> > Yes, that's dark frame subtraction. It activates when the exposure is
> >>=30 seconds at ISO 100-800 or >=1 second at ISO 1600. A second photo

> > will be taken with the shutter closed.
> >
> > NR is best left turned off until your exposures are long enough to
> > develop hot pixel problems. That can be over 10 minutes for some
> > Canons. The dark frame subtraction process can slightly damage a photo
> > by subtracting dynamic noise that doesn't correlate to noise in the
> > photo taken.

>
> Kevin,
>
> If I switch it on, does is stay inactive as long as exposures are < 30secs?
>
> Am I better off doing this in Paintshop/Photoshop? or is it worthwhile when
> the circumstances call for it?
>
> Cheers
>
> Alex


Experiment with it. I find that it's best off except in rare
situations. If you take an hour long photo of stars sweeping through
the sky, you'll have a hard time getting a software noise filter to
remove hotpixels without damaging trails. On the other hand, dark frame
subtraction in the camera knows exactly what pixels to blur out. The
downside is that you can't take another photo for an hour.
 
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wayne
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      05-12-2006
My understanding is that even if on, NR is only active on exposures of
30 seconds and more (except at 1600ISO, where it is 1 second or more).

Cheers,

Wayne

Wayne J. Cosshall
Publisher, The Digital ImageMaker, http://www.dimagemaker.com/
Blog and Podcast http://www.digitalimagemakerworld.com/
Personal art site http://www.artinyourface.com/

 
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