Dark Frame Subtraction & Light Pollution

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This is not an article explaining what a dark frame is or how to take one or how to subtract it from an image. It is only to share with you a few test images I made lately (my first actually); I am not relating the two topics (i.e; dark frame subtraction with light pollution!):

No dark frame subtraction

With dark frame subtraction

Notes:

  • In the first image, the purple color is mostly from the cam’s screen & lights; my cam is not designed to take exposures longer than 15 seconds (more on this & how to do it in a later post!)
  • In the images above, you can see vertical lines (most notable under Polaris) under stars; this is just the vibrations; I didn’t use a timer!

Effect of light pollution

You can clearly notice the glow above the mountain due to man-made lights. Also note that the image was taken around midnight when the sky appears (to our eyes) to be dark! To get a better picture of how much man-made light affects the night sky, here’s a close up image of them:

Hope these images give you a better picture of how dark frames & light pollution affect astrophotography & the night sky!

Thanks for reading šŸ™‚ and clear skies!

This post was originally published at theĀ Lebanese Astrophotographers blog.

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