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06-22-2008, 01:29 PM   #1
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Shadows.....

Hi guys...

What is the usual culprate for noise in the shadows but in the light is good in the same photograph?
the picture below was taken at 1/2000 and F16 at ISO 3200 (my brother took the shot, I have the cam set to auto
because I rubbish at settings)

E.G.

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06-22-2008, 02:34 PM   #2
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Signal to noise ratio.

Highlights -- Strong signal.
Shadows -- Weak signal.

Noise is the same anywhere on the sensor.

So you see the noise more where the signal is lower. Not much you can do about that.


Same for people who underexpose a shot and then push it in post processing and go complaining about the "horrible noise" a camera has, it's a situation they created by reducing the signal, creating a unfavorable signal to noise ratio. When you push a shot later in post processing you boost anything that is there, image detail and already visible noise.
06-22-2008, 04:55 PM   #3
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The photo you posted could have easily been taken at 1/500th of a second and ISO 800 for the same exposure with a better signal to noise ratio, as Morfic discusses above.

The scene is also a natural candidate for use of a split ND filter to reduce the tonal range between the brightly lit ship and background boats and the shadowed foreground boats. The more balanced tonal range that would result would enable a bit more exposure for the foreground, again improving the signal to noise ratio in the shadows.
06-22-2008, 05:23 PM   #4
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QuoteOriginally posted by PentaxPZ Quote
Hi guys...

What is the usual culprate for noise in the shadows but in the light is good in the same photograph?
the picture below was taken at 1/2000 and F16 at ISO 3200 (my brother took the shot, I have the cam set to auto
because I rubbish at settings)

E.G.
The culprit is underexposure. In the example you've shown, you are starting with several stops of underexposure by using ISO 3200. If I am not mistaken, your camera has a native ISO of 200, so ISO3200 is 4 stops of underexposure right off the get go.
Normal exposure is calculated at 18% reflectance. Anything that reflects more than that falls into the overexposure range, anything under 18% falls into underexposure.
Shadows tend to be less than 18% reflectance, and so will be underexposure. Add a few stops more underexposure to your example, and you are in the 6-7 stop of underexposure for the shadows, with your highlights probably just reaching normal exposure
Noise is bound to happen in this condition.

06-22-2008, 11:06 PM   #5
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Your brother definatelly butchered what could have been a wonderful shot.

ISO400 with a slightly small DOF and even with a shutter speed of 1/125 would have given a great shot.
06-23-2008, 12:41 AM   #6
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penzance

Almost the same picture taken last year with the backup dl2,iso200 f13 1/500.I think the clouds helped.

Last edited by vespa; 10-08-2012 at 01:20 AM.
06-23-2008, 06:11 AM   #7
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Original Poster
Thanks guys

well Like I said I leave the cam set to auto due to the fact I have no idea what settings to use!

And now the 70-300 lens used in this shot has died!
No zoom! Nooooooooooooooo!

only a month old, time to take it back!
Got another coming from Ebay and a teleconverter too.....
So will not be without one for long....
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