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<blockquote data-quote="Bob Blaylock" data-source="post: 226007" data-attributes="member: 16749">Definitely sensor noise.&nbsp; Looking at the EXIF data in this picture, I see that it was an exposure of more than fifteen minutes.&nbsp; To have that long an exposure, and not completely wash out the picture, there had to be very, very little light actually reaching the sensor.&nbsp; There's always going to be at least a little bit of noise in the sensor, but under more normal exposure conditions, it will be insignificant compared to the actual light that is being recorded.&nbsp; But here, you've got very little light, so the noise is more significant.&nbsp; Think of it as being like trying to watch a distant, weak station on an analog television.&nbsp; You get a lot of “noise”—hiss and static and “snow”.&nbsp; The same amount of noise is always there, but the stronger the signal, the less significant the noise appears.&nbsp; Here, you're intentionally giving your camera's sensor a very weak signal, and then wondering why you see so much noise.&nbsp; See also:&nbsp; <a href="http://en.wikipedia.org/wiki/Signal-to-noise_ratio" target="_blank">Signal-to-noise ratio</a></blockquote>

[QUOTE="Bob Blaylock, post: 226007, member: 16749"] Definitely sensor noise. Looking at the EXIF data in this picture, I see that it was an exposure of more than fifteen minutes. To have that long an exposure, and not completely wash out the picture, there had to be very, very little light actually reaching the sensor. There's always going to be at least a little bit of noise in the sensor, but under more normal exposure conditions, it will be insignificant compared to the actual light that is being recorded. But here, you've got very little light, so the noise is more significant. Think of it as being like trying to watch a distant, weak station on an analog television. You get a lot of “noise”—hiss and static and “snow”. The same amount of noise is always there, but the stronger the signal, the less significant the noise appears. Here, you're intentionally giving your camera's sensor a very weak signal, and then wondering why you see so much noise. See also: [url=http://en.wikipedia.org/wiki/Signal-to-noise_ratio]Signal-to-noise ratio[/url] [/QUOTE]

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