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inexplicable noise please help

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  #1  
Old 01-20-2009, 03:43 PM
DXM DXM is offline
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inexplicable noise please help

I don't understand this.

Tonight I took some shots in a studio, with lighting and flashes up the wazoo...
but I still got inexplicable noise in every shadow.

High amount of color noise and artefacts in the shadows. I'm using a Canon 30D with a Sigma 24/70 lens. I shot at iso100 1/160 f8.0-11.0 using either AWB or flash set WB.

anyone understand what went wrong.

Will be posting an unedited shot displaying what I mean as soon as I get home... still at work.

Please Help
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Old 01-20-2009, 04:48 PM
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Re: inexplicable noise please help

Did you shoot RAW or JPG? Yes, it would be best if you posted an image that we can examine.
Regards, Murray
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Old 01-20-2009, 05:27 PM
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Re: inexplicable noise please help

before commenting on the image - model - or composition itself, remember that this is a random image from the session, chosen for it's ability to display the problem I'm having rather than an example of my skills.

Comment: look at the edge of the softbox in the upper right corner, the fold of the skirt on the left side and in the shadows of the fold on her blouse (or whatever you'd call it)

My Level.
I am shooting at an intermediate level and photoshop at the same closing on semi pro

Image stats.
  • IMG_1616
  • canonEos 30d
  • RAW
  • 42mm
  • f/8,0
  • 1/125sec
  • ISO-100
  • Exposure manual
  • AWB
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File Type: jpg IMG_1616-01.jpg (51.3 KB, 103 views)
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Old 01-20-2009, 06:37 PM
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Re: inexplicable noise please help

The noise does not look like typical low light color noise. Its in other places other than the shadows. It is very possible that you have some chromatic aberation going on. If that is the case then the jpg compression would amplify the effect.
Can you post the RAW image somewhere with a link to it here. It would be more useful to examine the RAW file unprocessed in any way.
Regards, Murray
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Old 01-20-2009, 07:04 PM
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Re: inexplicable noise please help

Sorry Murray. I can't do that.
The model release I've got with this girl doesn't allow that, and I don't even give the RAW originals to my boss. When he needs shots that he can work with he get's hi-res TIFF's.

I work from the principle that if someone wants the raw files they have to buy the full rights to the image in which case I wash my hands of the pictures entirely.

What did you mean by chromatic aberation? Are you saying that the background is giving my camera the hiccups? Photographic terminologoy is one of my weaker sides and it is driving my friends nuts... especially when they need me to explain how I've done something. They're mostly schooled whilst I am selftaught
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Old 01-20-2009, 07:36 PM
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Re: inexplicable noise please help

OK, understood. Don't need the whole image. How about this piece below (arm, armpit, and bit of dress). When you open the image in ACR make sure it is set to open at 300 ppi and at orig camera size and in the color space that the image wass shot - see the area circled in red on the screenshot below.

Do not make any adjustments or move any sliders. Go to the sharpen tab and make sure that the Noise and Sharpen sliders are dragged to 0.

Open the image, crop the area shown in the 2nd sceenshot below and save as PSD - NOT jpg.

Chromatic Aberation is a function of the cameras lense whereby the channels are not exactly aligned. The effect is usually most notable on the edges and fringes of objects in an image. ACR has a tab that allows you to adjust / offset chromatic ab before opening the image.
Regards, Murray
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File Type: jpg DMX Partial.jpg (23.3 KB, 44 views)
File Type: jpg DMX Screenshot.jpg (189.6 KB, 22 views)
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Old 01-20-2009, 09:01 PM
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Re: inexplicable noise please help

>>I'm sorry... it's 4 am here and I keep loosing track.
just realized that I don't know anywhere to post such a large file (4,7mb when cropped)
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Old 01-20-2009, 09:22 PM
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Re: inexplicable noise please help

hmm just got told what was wrong and I feel like an omelet (having egg on my face).

Apparently my lens-hood is what's called a tulip cut. i.e it doesn't cover all of the circumference of the lens. and I was shooting against the light with the eval set to (o) if you understand what I mean by that...argh braaaiiins.

'parently this causes C/A quite often.
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File Type: jpg setup.jpg (45.8 KB, 10 views)

Last edited by DXM; 01-20-2009 at 09:31 PM.
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Old 01-20-2009, 09:26 PM
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Re: inexplicable noise please help

In Adobe Camera RAW, the lens correction filter is the 4th tab from the right. Try it on the image. It looks like the Green Magenta is the problem in your image but you can try both sliders. Be sure to zoom in to 100% view. Good Luck,
Regards, Murray
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Old 01-20-2009, 09:33 PM
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Re: inexplicable noise please help

mostly use Rawshooter 'cause adobe is a bitch that doesn't like me but i'll try it. thanks

apparently that's the one setting that acr won't let me fix. it's got the red/cyan and the blue/yellow but can't find any green/magenta

Last edited by DXM; 01-20-2009 at 09:40 PM. Reason: tried it
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