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How to Maintain Star Colour in Your Star Trail Images

Colour in star trails

Shooting star trails is easily one of my favourite astrophotography subjects. Capturing the motion of the stars as they cross the night sky, combined with something interesting in the foreground makes for memorable photos.

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But something many people seem to miss is capturing the star colour.

the colour of starsNot all stars are created equal. They vary from blueish-green tones, to white, yellow, orange and red. The colour of a star indicates its surface temperature. Our own sun is yellow, which is the average mid range of star colour.

Stars with a blueish-green hues are much hotter than our sun, but have a shorter lifespan.
White to blue stars are also hotter than the sun, have a longer lifespan than blue stars, but not as long as our sun.
Yellow stars, like ours, are normally in the middle of their life expectancy.
Orange to red stars are approaching the end of their lives, they are bigger and cooler than our sun.
(Star colours explained)

Capturing these colours in star trail images can aid in adding a scientifically accurate and dramatic effect to your composition.

And the secret: Don’t blow out your stars!

Photographing star trails should not share the same settings as photographing the Milky Way.

  1. Lower your ISO. Yes, you need to amplify the light you collect, but you’re not shooting for tiny light sources in one frame. When you compile your star trail data, the multiplicative effect will highlight the stars sufficiently and bring out their colour.
  2. Stop your aperture down a full stop if you have fast glass (f/2.8 or faster should be dropped to around f/4 or so). This will also allow you to cut that tiny bit of “star bloat” around your stars to help give you clear defined streaks of light.
  3. Apply sufficient saturation to your image to enhance star colour in post production (something that would be difficult had they been blown out).
Star colour in star trails
316 x 30seconds exposure. Total 158min. ISO800. Shot in a dark location.

My go-to settings for shooting star trails:

In my backyard: (YES, in a very heavily light polluted area!)
Shutter speed: 30 sec, continuous shooting enabled.
ISO 200 or 400.
F/4 (my lens is capable of F/2.8)

In dark skies:
Shutter speed: 30 sec, continuous shooting enabled.
ISO 800-1600 at F/4

For foreground lighting you can use higher ISO settings or light painting techniques. It’s best to experiment with these prior to shooting your star trail sequence so that you’re assured of having lighter frames to blend in post-processing.

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About the author

Tanja Schmitz

Tanja is the co-founder of PhotographingSpace.com with her husband, Cory. She is also the co-owner of several telescopes and Celestron mounts, too many cameras, and not enough hard drive space.

An internationally commissioned and published astrophotographer, her work has been used in multiple online and print publications. Tanja was also shortlisted for the Astronomy Photographer of the Year award.

8 Comments

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  • Thanks for the pointers Tanja. I’ve been shooting at F/2.8 and intrested to see how my images turn out at f/4. I’ve recently upgraded to a Nikon D610 which has the continuous shooting mode but not used it, I assume i just turn it on and not put a delay between shots on the remote timer? Is there a danger of over cooking the sensor using continuous shooting mode?

    • Hi Gareth,

      You definitely don’t need to worry about using continuous shooting mode, it’s not like the video modes. And yes, you assume correctly — just enable it and use no delay in between shots!

      Cheers,
      Cory

    • When shooting in Raw format, you can adjust the white balance in post-production. But starting off on the right value always helps, and definitely required if you’re shooting to Jpeg. White balance settings can vary from 2,800 up to as high as 4,800. It is all dependent on the darkness of the night sky of your shoot location. You will find that in more light polluted areas a cooler colour temperature like 3,200 up to 3,800 will work well – and in darker skies 4,200 – 4,800 might be better. I suggest a few test shots before you start shooting to find a value that works with your location. But again – that’s why shooting Raw is always better. Also note that the star colour is also a result of not over-exposing the stars. So while in normal Milky Way photography you’d want to push your ISO to the maximum – dial it back slightly for star trails to retain better star colour. Good luck! Please share your results with us!

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