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dust motes

 
 
pshaw@emmet.com
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      04-03-2005
i tried finding dust motes on my 20d following the article in the
'photoshop user' mag and put the camera on a tripod, set my 100mm lens
to 3 foot manually, iso 100 and took some pix of a white wall inside
and a clear blue s. calif. sky outside. i then opened the raw file in
photoshop cs, clicked 'ok' and dragged the 'show as white' layer from
the 'dust catcher psd' (downloadable from their site) on top of the
white wall and then on top of the blue sky pix.

when i used the white wall pix i got a variety of colors showing and
at the bottom 3 faint round darker circles and one somewhat darker
circle to the right of this. when i used the blue sky and once again
dragged the 'show as white' layer on top, i got a overall greenish
image and once again the same faintly grey circles at the bottom and a
much more pronounced circle at the bottom right.

are these dust motes? bad pixels?

tia ... steve
 
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Joseph Meehan
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      04-03-2005
http://www.velocityreviews.com/forums/(E-Mail Removed) wrote:
> i tried finding dust motes on my 20d following the article in the
> 'photoshop user' mag and put the camera on a tripod, set my 100mm lens
> to 3 foot manually, iso 100 and took some pix of a white wall inside
> and a clear blue s. calif. sky outside. i then opened the raw file in
> photoshop cs, clicked 'ok' and dragged the 'show as white' layer from
> the 'dust catcher psd' (downloadable from their site) on top of the
> white wall and then on top of the blue sky pix.
>
> when i used the white wall pix i got a variety of colors showing and
> at the bottom 3 faint round darker circles and one somewhat darker
> circle to the right of this. when i used the blue sky and once again
> dragged the 'show as white' layer on top, i got a overall greenish
> image and once again the same faintly grey circles at the bottom and a
> much more pronounced circle at the bottom right.
>
> are these dust motes? bad pixels?
>
> tia ... steve


Question. Why are your worried?

It seems a lot of people spend a lot of time trying to hunt down
immaterial gremlins when the time could be better spend perfecting one's
art. In short, if you don't see a problem in the results you are getting,
you don't have a problem.

--
Joseph Meehan

Dia's Muire duit


 
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Chas
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      04-03-2005

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
|i tried finding dust motes on my 20d following the article in the
| 'photoshop user' mag and put the camera on a tripod, set my 100mm lens
| to 3 foot manually, iso 100 and took some pix of a white wall inside
| and a clear blue s. calif. sky outside. i then opened the raw file in
| photoshop cs, clicked 'ok' and dragged the 'show as white' layer from
| the 'dust catcher psd' (downloadable from their site) on top of the
| white wall and then on top of the blue sky pix.
|
| when i used the white wall pix i got a variety of colors showing and
| at the bottom 3 faint round darker circles and one somewhat darker
| circle to the right of this. when i used the blue sky and once again
| dragged the 'show as white' layer on top, i got a overall greenish
| image and once again the same faintly grey circles at the bottom and a
| much more pronounced circle at the bottom right.
|
| are these dust motes? bad pixels?
|
| tia ... steve

You got the darker circles AND greenish image along with faintly grey circles
and a
much more pronounced circle against a clear blue California sky? You're
screwed.


 
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Ed Ruf
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Posts: n/a
 
      04-03-2005
On Sun, 03 Apr 2005 20:45:01 GMT, in rec.photo.digital (E-Mail Removed)
wrote:

>i tried finding dust motes on my 20d following the article in the
>'photoshop user' mag and put the camera on a tripod, set my 100mm lens
>to 3 foot manually, iso 100 and took some pix of a white wall inside
>and a clear blue s. calif. sky outside.


Most important set small aperture, like f/22
----------
Ed Ruf Lifetime AMA# 344007 ((E-Mail Removed))
See images taken with my CP-990/5700 & D70 at
http://edwardgruf.com/Digital_Photog...ral/index.html
 
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Jim Townsend
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      04-03-2005
(E-Mail Removed) wrote:

> i tried finding dust motes on my 20d following the article in the
> 'photoshop user' mag and put the camera on a tripod, set my 100mm lens
> to 3 foot manually, iso 100 and took some pix of a white wall inside
> and a clear blue s. calif. sky outside. i then opened the raw file in
> photoshop cs, clicked 'ok' and dragged the 'show as white' layer from
> the 'dust catcher psd' (downloadable from their site) on top of the
> white wall and then on top of the blue sky pix.


I have no idea why they tell you to use a tripod or to focus
the lens to a certain distance. If you want to bring out
dust on the sensor, all you have to do is use a very narrow
aperture.

Put the lens in Av mode and make sure you narrow it down to
something like f/22. Then, shoot a clear or cloudy sky.

If there's dust on your sensor, you'll *certainly* see it then.

I have no idea why they tell you to use a tripod or to focus
the lens to a certain distance.

> when i used the white wall pix i got a variety of colors showing and
> at the bottom 3 faint round darker circles and one somewhat darker
> circle to the right of this. when i used the blue sky and once again
> dragged the 'show as white' layer on top, i got a overall greenish
> image and once again the same faintly grey circles at the bottom and a
> much more pronounced circle at the bottom right.
>
> are these dust motes? bad pixels?


Didn't the magazine add have any example shots of dust on
a sensor ?


 
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