I recently took a couple of shots of the same scene, altering only the shutter speed. First one is 99 sec and the second is 15 sec. WHy does the 15 sec exposure have a lot more noise than the 99 sec one? I thought that longer exposures are more prone to noise so I had thought that the 99 sec exposure would have more noise. Other than that settings were the same. Exif data intact.
What gives? And how can I avoid noise like this?
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