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Old Jun 12, 2006, 8:49 PM   #1
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Hi Guys

Was after your thoughts of the amount of noise shown in this 100% crop from my 5D. I have also attached the overall pic too. I am concerned there maybe something wrong with my camera. Any thoughts ???

5D

sigma 10-20 lens

ISO 200

F22

6 Sec exposure

using ND9 filter and ND9 grad also cokin type

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Chris







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Old Jun 12, 2006, 11:00 PM   #2
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Looks like a ton of jpg artifacts... hard to see through that?
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Old Jun 12, 2006, 11:07 PM   #3
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I also shot in raw and converted using adobe raw converter through photoshop cs



cheers

chris
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Old Jun 14, 2006, 5:03 PM   #4
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anyone have nay thoughts ?? I dont want to go sending off for repairs if this is believed to be normal amount of noise.

cheers

chris
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Old Jun 14, 2006, 5:13 PM   #5
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Again, I dont think there is any way to answer that with these web images. I dont see noise, I see artifacts.
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Old Jun 14, 2006, 5:19 PM   #6
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Was your exposure off (using Exposure Compensation in ACR to get it where you wanted it)?

It's tough to tell from your example what the problem is.

But, if you underexpose a shot and brighten it, it's just like shooting at higher ISO speeds, and you can get lots of noise and artifacts if you push a shot too much.

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Old Jun 14, 2006, 5:23 PM   #7
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Ok then.

Could you please xplain a bit further the artefacts issue which i could be having and how i rectify this when shooting ?

for example when shooting the scene that i have and require the longer shutter speed to blur the water ??



thanx for all advice given



cheers

chris
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Old Jun 14, 2006, 5:31 PM   #8
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Did you push the shot any (brighten it using Adobe Camera Raw using Exposure Compensation or other sliders from where you exposed it at)?

If so, that's probably the source of your problems. Just expose it brighter.

If you really want the 6 seconds, open up the aperture a little and expose for the same length of time to give a brighter exposure to begin with that you don't need to push any using software. It's not like you need f/22 with a lens that wide anyway for DOF purposes. ;-)

If you underexpose a shot, it's going to have more noise and artifacts when you brighten it later (if that's what you did).

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Old Jun 14, 2006, 5:59 PM   #9
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Ok



The ACR settings were as follows (all auto checked)

As shot white balance

exposure+0.85

Shadows 12

Brightness 92

Contrast +50

Saturation 0



Would that sound like it is pushed too far ??



thanx again for the help

cheers

chris
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Old Jun 14, 2006, 6:18 PM   #10
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It shouldn't be for ISO 200, unless you were messing around with curves, too.

It's hard to judge from your crop what may have been happening.

I'd try exposing it a tad brighter and see if that makes any difference. You may also want to try it with noise reduction both on and off (by default, it's probably kicking in on exposures of 1 second or longer).

I'm also wondering if we could be seeing light reflecting off of the ocean foam as it's moving around (with something similar happening with the clouds in the sky), giving the appearance of noise and artifacts (when it could just be theresult of movement over 6 seconds).

I haven't done any long exposures with a KM DSLR to better understand it's behavior for that purpose. 6 seconds is much longer than I'd normally expose an image.
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