You might have seen an image like this before, or maybe this is the first time you encounter those stripy stars… They are called “star trails”, an effect I simply love. Star trails literally show the paths (or trails) the stars travel through the night sky. It actually freezes about an hours worth of time, in one photo! In this tutorial I will teach all about photographing star trails and how you use post production methods for sensational results.
So, how do you shoot Star Trails?
Late November I travelled to Jordan and spent a few nights in the breathtaking desert of Wadi Rum. When driving around in a 4×4 I spotted a few rock formations that I really liked. After taking a few test shots to see how the image and framing would turn out, I settled for this location. Looking down onto the open desert plain through a gorge in the rocks gives a great depth to the picture.
It was actually a very bright night: the moon was out, almost full, which normally is not the best time for astro photography. Because of the bright ambient light of the moon the intensity of the stars is quite low. However, you can also use the moonlight to your advantge, and that’s what I’ve done for this particular image. The entire landscape you see is lit up by our friendly lunar neighbour! No photoshop or daytime photography was used to brighten the scenery… I positioned myself ensuring the moon was on my righthand side, rising towards my back, so it wouldn’t enter the frame.
The other advantage of using the moon this way is the colour of the sky. A beautiful blue-ish haze colours the otherwise black sky. Just on a sidenote: it will be impossible to capture the milkyway when the moon is out, since you need a pitchblack sky to be able to see all the stars of this galaxy! Maybe you should pick another night when the moon is awol!
Star trail camera settings:
Now you know why I took the image the way I did, I will explain how to capture those beautiful stripy stars. This technique, once you get the hang of it, is actually quite straight forward. It is a technique called image stacking. The photo you see here is a combination of 85 stacked photos, with the following camera settings:
- Exposure time of 30 seconds per photo
- Aperture f4
- Iso 400
- Focal length 16mm
- Taken over a timeframe of about 45 minutes.
Set your camera to Continuous Shooting Mode
On a sidenote: if you shoot star trails during a pitch-black night as you normally would (when there is no moon), you will have to increase your iso setting to about 1600-3200 iso for a f4 lens, or about 800-1600 iso for a f2.8 lens.
To start, you need a very sturdy tripod, since your camera cannot move throughout the photographing process of about an hour. I use the Rollei C6i carbon, which works a treat! To take 85 photos without touching the camera, I use the interval timer and continous shooting mode on my Canon 5D mark IV, but you can also use a remote trigger. If you don’t have any of these options, use a piece of rubber (like a piece of erasor) and ducktape this over the shutter button of your camera to keep the button pushed down: it does the trick as well!
So, because of the rotation of the earth, stars will move through the sky. If you take photos of 30 seconds each, the stars actually start to show up as short lines on your image: the start of our star trail. If you combine 85 photos (or more) and put them on top of each other (stacking), you will end up with the beautiful star trails as you see them in this picture. You can do this with software like Photoshop or Lightroom, but I prefer to use StarStaX. This free software is specially designed to stack images like this and creates a perfect result. Download the software here…
Post-processing workflow from A to Z – Lightroom:
Once imported in Lightoom, I corrected only 1 of the 85 images: I corrected the colour tone to give the sky a bit more blue, lowered the brightness, increased the contrast, highlights and whites (to let the stars stand out a bit more), and darkened the shadows and blacks (to ensure a correctly exposed & dark sky). A little bit of vibrance gives the photo a more natural and warm colour effect. Once you’re happy with the result of the adjustments of your first photo, you select all the photos you want to adjust and hit the “synchronise settings” button. This ensures the same settings will be applied to all of your selected images.
Lightroom before adjustments:
Lightroom after adjustments:
Once finished in Lightroom, export the images and open them in StarStax. StarStaX will combine all 85 images into one single image. Under the header “blending mode” you will select the Gap Filling mode, to ensure smooth blening and trails. In this case I also selected the Comet mode, which allows the startrails to soften off towards the end. The “subtract black images” option will reduce the noise of the image, if you have taken a completely black image with the exact same settings as you used for the startrail photos.
Hit the start button and sit back watch your startrails come to life: StarStaX will do the rest..
After StarStaX has worked its magic, import the final image to Photoshop to finish off the colours and possible noise. In this particular case, the foreground brightened up completely. This is because the StarStaX software looks for the brightest pixels in your pictures (the stars), and only shows these bright areas in the final image. However, because the foreground was lit up by the moon, all single images had quite a bit of brightness in them. All these bright images stacked together will create an over-exposed foreground.
In Photoshop I simply opened 1 of the pictures I took (I looked at the shadows and picked the nicest foreground), added a black mask and brushed in the parts of the foreground I wanted to use. In this way I also brushed out the light-trail of a car driving past… A last colour & contrast correction, a bit of sharpening, a bit of cropping, adding a vignet and done!
Photoshop before adjustments:
Photoshop after adjustments: