Dark Frame Subtraction & Light Pollution


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


  • 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.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s