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Milky Way Exposure Calculator (v1.0)

This tool for photographing the Milky Way will give you the estimated shutter speed required based on your ISO, aperture and focal length settings. There are a few things that guide most astrophotographers when deciding which exposure settings to use for photographing the Milky Way. Astrophotography has a lot of variables that will affect what determine the best exposure. Some of them are from the environment (light pollution, moonlight, clouds, etc) and some are in the hands of the photographer (lens focal length, sensor size, f/number, etc).

Similar tools are available for the Moon and lunar eclipses.

Camera Settings
Sensor Size :  Maximum desired ISO : 
Lens Focal Length :  Lens aperture (f/Number) : 
Suggested shutter speed : 


The calculator tries to determine the best settings to produce a neutral exposure, so you may need to adjust based on your results. It outputs an exposure target of -8 EV which is what one would recommend starting with for most astrophotography in dark sky locations with a regular camera/tripod setup and no fancy tracking equipment.

  • To display the suggested time exposure, select the camera sensor size, the maximum ISO, the lens aperture (f/number) and its focal length. The time exposure will then be displayed and computed every time you modify one of those parameters.
  • The time exposures are only given as a guide. You should bracket your exposures one or more stops to take into account the actual sky conditions and the variable nature of these phenomena.

Tips on taking successful Milky Way pictures

  • Use a sturdy tripod.
  • Get a good lens with the lowest possible aperture, preferably 2.8 or less.
  • Enable mirror lockup to minimize vibrations and use a cable release.
  • Shoot in RAW.
  • Set the white balance setting to either Daylight or Tungsten.
  • Set your lens on Manual Focus and focus for infinity.
  • Bracket your shots 1 or 2 stops on each sides.

We usually cannot rely on what the photo looks like on the back of the LCD. Enabling the histogram view on your camera will let you adjust properly the exposure. Typically we will desire a histogram that shows peaks toward the center of the graph from left to right.

Last page update on May 3, 2004.
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