10 Useful Tips for Photographing Beautiful Star Trails
- By: Luis Argerich
Star Trails are created because of Earth’s rotation during a long exposure photo. The stars fixed (almost) in the sky show trails along with the rotation of our planet. Here are some useful tips to create beautiful star-trails photos.
1. Focal Length Matters
This is simple: The longer the focal length the longer the trails. With a wide angle lens you need really long exposures in the order of minutes for the trails to be noticed, with a telephoto lens the trails appear in a few seconds but composition becomes more difficult.
2. The Area of the Sky Matters
The length of the trails also depends on the area of the sky you are photographing, the closer you are to the celestial pole (see tip 7) the shorter the trails will be. The reason is very simple, all the stars travel in a complete circle around a fixed point of the sky every 24 hours. So as you get closer to the celestial pole the stars travel less distance per unit of time.
3. Expose for the Foreground
Exposure time can be difficult for star trails, my recommendation is to start finding a good exposure for the foreground with a very high ISO such as 6400, once you find that exposure then just compute the equivalent exposure for a lower ISO to get longer trails. For example if the foreground looks fine at 2” ISO 6400 then your choices are:
4” ISO 3200; 8” ISO 1600; 16” ISO 800, 32” ISO 400, 64” ISO 200, 128” ISO 100
4. Several Photos are Better than One
There are two ways to get star trails: A single photo with a very long exposure or several shorter exposures combined together. The second method is safer because if something goes wrong you lose only one frame and not the complete image. Several things can work against your work: Car lights, runing out of battery, somebody with a flashlight, clouds, etc. The final result can be composed with layers in a photo editor or using specialized software such as Startrails.exe (from startrails.de)
5. Composition is Everything
The key for star trails photography is to find a good composition, the trails are nice on their own but you need a landscape or a foreground object to make the photo interesting. A silhouetted object can frequently be interesting just make sure you have the complete scene in focus!
6. About Equipment
You need a solid tripod, if the tripod moves you are doomed. Make sure the tripod is stable and shielded from the wind. A remote intervalometer is also a great tool, you can program it to take the exposures for you while you take a Coffee. Don’t forget to use a fully charged battery.
7. How To Find the Celestial Pole
You can find the Celestial Pole using a compass and knowing your latitude, with the compass aim north if you live in the north hemisphere or south if you live in the south hemisphere. Then the pole is at the same height as your latitude. So if you live at 35 degrees north the celestial pole is 35 degrees high in the sky pointing north. If you live in the north hemisphere and you know how to find Polaris that works perfectly too.
8. In Camera Noise Reduction
If you take several photos make sure you have in-camera noise reduction off to avoid gaps in your trails. If you go for the single exposure approach then you can turn it on but the photo will take twice as long as planned. Make sure you have good batteries for it!
9. Minimize Gaps
To minimize gaps in your trails try to use the shortest possible interval between photos if you take several exposures. You win nothing waiting a few seconds and the trails will look like dashed lines.
10. Post-Processing Tips
When post-processing star-trails start with noise reduction, then adjust contrast and saturation and finally sharpen to taste. Removing noise is the most important step, then its just about your taste.