You may have noticed many of my night sky images have been plagued by noise. By using ISO 800 - 6400, the exposure time can be shortened so that celestial objects do not blur from the rotation of the earth. You've seen those images where stars leave circular trails, right? Those look cool, but in order to see what is up there, you don't want that to happen, so I try to shoot with exposures of only a few seconds. Using high ISO sensitivities causes grain-like noise to become very apparent
Yesterday I bought Grain Surgery from Visual Infinity, a Photoshop plugin that reduces the effect of 'high ISO' noise. This should greatly improve my astronomical work.
Here's a before/after example.
