Techniques to take pictures of star trails

Techniques to take pictures of star trails


Introduction :

I’ve always been amazed looking at night shots that show the movement of stars in the sky. No, it is not shooting stars, but star trails.
Cet été, j’étais dans les Alpes, à Puy Saint Vincent, avec le beau ciel clair et limpide que l’on peut imaginer en altitude. J’ai donc pu tester mon équipement sur ces techniques.
Last summer, I was in the Alps, at Puy Saint Vincent, with beautiful crystal clear sky that one can imagine in altitude. I was able to test my equipment on these techniques.


Equipments :

To take pictures of star trails, you must master your equipment but also it has to be manually settable.
You need a digital camera, if possible with a B mode, but this is not an obligation. However you must be able to adjust your aperture and exposure time, and even better your focus manually.
You also need a remote trigger with the option “button kept pressed” to prevent vibration and start the triggering without worry.
A good tripod to snap your camera, a solid surface, with minimal wind to avoid unwanted vibrations.


Technique 1 for star trails – Long exposure :

In this case, with the B mode, you start a long exposure using the option “button kept pressed” of your remote control button.
This will generate a single image file. However, the important point : at the end of the shooting, your camera will do a post-treatment that will last almost as long as the shooting itself. So do not neglect the battery!
In addition, your sensor will work without stopping for the duration of the acquisition which will create hot spots. They are overheat pixels that stop working (temporarily for most, alas definitely for some) and issue a white dot like a star. Except that this is of course fixed. It is better to be careful.
Here is the result :


Technique photo étoile filée - exposition longue



Exif : 45 minutes exposure / aperture 6.3 / iso 200 / photo taken between 23h and midnight with a beautiful dark night.

First observation, it looks like it is daylight! Blue sky, mountain clearly visible, there is only the overexposed tree in the first plan that looks abnormal.
We also see the passage of a plane and we can not do anything.
Even if the effect is nice, I was a little disappointed because the star trails are not very visible. So I tried a different technique.


Technique 2 for star trails – The burst:

In this case, the B mode is useless. You must set your camera in burst mode, fast mode if you have a choice. Choose a shutter speed of 2s, at least the recording time will be quick and will not create lag time between shots.
Start the burst with the remote control, always using the option “button kept pressed”. You will get several thousands of pictures by the time you leave your camera. Do not underestimate your memory card.

You will also use a very specific editing software. For my part I use Starmax. This software adds the bright areas of the pictures of your series.

Here is the result :


Technique photo étoile filée - rafale



Exif : exposure 26 minutes (780 x 2)/ aperture 2.8 / iso 800 / photo taken between midnight and 1AM in a moonless night.

Anyway, the curve of the stars is beautiful and shows that the universe revolves around the earth our earth is turning on itself around an axis.
Autant le dire, je préfère largement ce résultat même s’il demande plus de travaille en post-traitement. On conserve un ciel très noir et donc un contraste naturellement profond du coup les étoiles filées sont très visibles.
Much to say, I prefer this result even if it requires more work in post-processing. We keep the darkness of the sky and therefore a naturally deep contrast that make the star trails very visible.


My conclusion :

When I will have the opportunity to redo pictures of star trails, I’ll be more careful in my composition.
– Choosing a spot more photogenic than the sight of a balcony.
– Incorporate the polestar to properly highlight the effect of rotation around an axis.

But I definitely prefer the second version, which has a more natural and therefore more fantastic look.