How to Calculate Arc Seconds Per Pixel

by Margaret Worthington

The measurement of arc seconds per pixel is used when taking pictures of the sky for astronomical purposes. An arc second is a unit of measurement of the sky, and is equal to 1/360th of 1 degree. To get accurate photographs that are of good quality, it's important to find out how many arc seconds per pixel your camera equipment can record in. This measurement is easy to figure out, thanks to a simple formula.

Step 1

Locate the pixel size and focal length of your camera in the required dimensions (microns and millimeters, respectively). This information should be in your camera's technical manual. If you don't have the manual, contact the camera's manufacturer for the information, since you will need to be exact in your calculations.

Step 2

Multiply the pixel size of your camera in microns by the focal length of your camera in millimeters.

Divide this number by 206.265 to calculate the arc seconds per pixel resolution of your camera.

Items you will need

  • Calculator
  • Pixel size of your camera (in microns)
  • Focal length of your camera (in millimeters)

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About the Author

Margaret Worthington has been writing and editing since 2001. Her work includes editorials and articles for a college newspaper, toy articles for Hasbro, copy-editing a romance novel and rewriting a publication for "GreenBlue." Worthington holds an Associate of Arts in English and journalism from Piedmont Virginia Community College and is pursuing a Bachelor of Arts in English and journalism from the University of Virginia.

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Photo Credits

  • refractor telescope image by Jim Mills from Fotolia.com