Noise using a snoot for a dark image

I thought I would try out my snoot on one of our unlucky dogs and I noticed how much noise I get when shooting low light. I've noticed this in the past on outdoor images too at night. (exporting as a jpg and uploading it to my smugmug has only made it worse...)

I'm shooting ISO 100 and a quick shutter. What would cause this?

This is out of the camera (30D), F9, IS0100, 1/100

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This kind of noise is common.

The best way to prevent it in that kind of image is to expose to the right. That means you expose brighter (but not so bright that you begin to clip channels in the highlights), shoot RAW, then use your RAW conversion software to bring the exposure down.

There is also plenty of software that handles this kind of noise pretty well. I use Noise Ninja, but Adobe Lightroom's noise reduction sliders do a decent job.

Curtis N wrote in post #8544065
This kind of noise is common.

The best way to prevent it in that kind of image is to expose to the right. That means you expose brighter (but not so bright that you begin to clip channels in the highlights), shoot RAW, then use your RAW conversion software to bring the exposure down.

There is also plenty of software that handles this kind of noise pretty well. I use Noise Ninja, but Adobe Lightroom's noise reduction sliders do a decent job.

Thanks Curtis, I will try to expose brigther and take it down in lightroom.
I've never played too much the the LR noise reduction but i'll give it a go.

What is actually causing it? I thought noise basically came from either high ISO or long exposure. Is this a limitation of my camera/sensor?

It's about the signal/noise ratio. Photons hitting photocells in the sensor create voltage which is recorded. But voltage also comes from other sources, which produces noise. It appears worst in dark areas because there is less light to produce voltage (less signal).

It's worse at high ISO settings because the camera is amplifying the noise as well as the signal. Sort of like trying to listen to a distant, weak station on your radio. When you turn up the volume, you also turn up the static.

So when you expose brighter, you increase the signal (the voltage actually produced by photons), which increases the signal/noise ratio.

More info here:
http://www.luminous-landscape.com/tutorial​s/expose-right.shtml

Thanks Curtis. Interesting read.