There are a few ways of getting into astrophotography that are as easy yet at the same time as rewarding as composing stunning star trail images.
Star trail photography might sound like an exotic niche to delve into, and it certainly doesn’t come without a certain learning curve. As long as you start off on the right foot, there’s no need for it to be deeply frustrating either!
That’s what today’s guide is going to be all about! Let’s take a look at everything you need to know when shooting star trails, from basic techniques to more advanced tips and tricks for every kind of astrophotographer!
Basic Prerequisites for Great Star Trail Photography
First, let’s assess the most essential things to take into account when heading out to capture star trail pictures. While it’s definitely possible to get good results following a different method, the following represents the foundation of techniques that most professional astrophotographers use.
Because of that, I highly recommend internalizing these tips and applying them if you haven’t already!
Pick a Suitable Location
To photograph star trails with success, you’ll want to maximize the amount of starlight entering your lens. A big part of that involves choosing the right night sky to point your camera at. Not every night is cut from the same cloth in astrophotography. You’ll definitely want to hunt for a quiet spot with very little light pollution.
The clearer and less obstructed or hazy the sky looks to your naked eye, the better it will look on camera, too!
Also, note the presence of the moon. Depending on the moon phase, it might significantly contribute to ambient light in your frame. A full moon especially can seriously affect the optimal exposure time and clarity of your star trail photography.
Hence, if you can at all afford to, consider heading out during a new moon or shortly after sunset to avoid stray moonlight.
Look for Polaris or the South Celestial Pole
If you wish to shoot photos with well-defined circular star trails the way you might have seen them in other people’s work, you need to get your bearings straight.
I mean that literally! In order to create a star trail image where the trails appear to rotate around the viewer, you need to trim your camera lens onto the celestial poles with precision.
Celestial poles are the “poles” of the celestial sphere. You can imagine the celestial sphere as a ball-shaped background of outer space on which, we can picture, all the night’s stars are projected onto.
Just like Earth, the celestial sphere also has its own celestial equator, and hence two poles, one in the north and one in the southern hemisphere.
If you yourself are based in the northern hemisphere of the Earth, you should look for the north celestial pole. That’s the North star, Polaris, visible just at the tip of the “handle” of the Small Dipper.
If you live in the southern hemisphere, look for the Southern Cross star formation. Draw a mental line going where the row of stars inside the Southern Cross is pointing.
Try to find the intersection between that line and another imaginary line emanating from Alpha and Beta Centauri, “the Pointers” (which should be visible just next to the Southern Cross in the night sky), parallel to the horizon.
That intersection is (roughly) where the South Celestial Pole is located.
Bring a Tripod
This one should be a no-brainer, but just in case: don’t even try shooting star trails without the help of a tripod! Camera shake can easily kill even the most promising shot when dealing with the long exposures that star trail images require.
If you want special effects like circular trails, you need to position your camera with a certain level of precision and leave it there. To do so in this way is basically impossible to do hand-held.
Equipment and Camera Settings for Star Trail Images
Star trail photography isn’t strictly limited by gear. Even a basic low-end kit can be used to great effect with the right technique! However, by carefully utilizing your camera settings and equipment to their fullest, you can achieve something truly stunning!
Let’s find out which kinds of cameras, lenses, and camera settings are best-suited to star trail photography.
Make Sure to Select a Low to Moderate Focal Length
While your lens focal length doesn’t play a crucial role in rendering star trails by itself, I would recommend avoiding anything near the telephoto range. This is simply because a longer lens means a smaller angle of view and fewer stars in your frame.
Instead, I suggest you pack a wide angle lens or a standard fast 50mm. Anything that would perform well in other genres of nighttime and landscape photography will likely do well for star trails, too.
Avoid High ISOs
It makes sense to jack up your ISO setting for rendering star trails more brightly and allowing them to “pop”. However, I urge you to resist this temptation. While high ISOs make perfect sense for regular nighttime photography at faster exposure times, a star trail image has to be photographed over the course of at least a few minutes. The stars simply don’t move that fast, meaning you won’t get any trails at fast shutter speeds! And if you drive up your film speed, know that you might also severely overexpose.
Apart from that, you’ll also want to avoid high ISO numbers due to noise. Severe sensor noise can actually render some of the weaker stars in the night sky hard to see. This compounds when using a wide-angle lens, of course. The low magnification of such a lens makes many stars appear as only tiny individual dots, meaning they can easily be obscured by heavy noise.
You can try to fix these kinds of flaws with noise correction in post-processing. Still, it pays off and is much less of a hassle to dial in a lower ISO, to begin with.
Take Your Fastest Lens
This might seem counter-intuitive, but star trail images actually benefit a ton from having a fast lens. Even in optimal conditions under a clear night sky, most stars are going to appear fairly dim.
Jacking up your ISO to expose more under low light conditions is not a viable idea, as we just went over. And you need your very slow shutter speed in order to display those stunning trails in the sky, so that’s off-limits, too!
The only major exposure setting that allows you to selectively dial in the relative brightness of your star trails is your lens aperture. At diaphragms smaller than f/3.5, star trail photography can get really challenging. Depending on light pollution levels and other environmental factors, you might have trouble getting clear trails at all.
I would suggest taking the fastest wide-angle or normal lens you have available to you. There’s generally no point in diminishing returns here as you can stop down anyway to create a more toned-down effect if you so wish, so just make sure to go for the widest light-catcher you have in your camera bag.
Make Sure to Set Your Camera to Manual Mode
With this, you’re out of options. The whole concept behind photographing star trails requires you to shoot longer exposures than what is normally used in conventional daytime photography.
Only that way can the movement of the stars emerge as exaggerated, surrealist trails in the night sky.
Because your camera will not be capable of automatically calculating exposure for you at these very long shutter speed settings, you’ll need to do it yourself. So, set your camera to manual mode and keep a low ISO to shoot star trails effectively!
Set Your White Balance
Most likely, color rendition factors into your vision for your star trail image a great deal. Some people might prefer to shoot star trails in monochrome. But for many, the brilliant colorful glow of their night sky images remains an essential aspect of the composition.
In general, you should use cooler temperatures for white balance when shooting star trail photographs. This does depend on the time of year, the hemisphere you’re in, the phase of the moon, and plenty of other factors. However, cooler-than-daylight is usually a safe bet.
Feel free to also use your camera’s auto white balance setting. Do a few test shots at faster exposure times to check whether this generates usable results.
Shoot RAW Files For Better Editing Headroom
I suggest you shoot star trail photos in RAW format. That’s much better than leaving it all to chance and having a small detail like white balance or ISO ruin your image.
This way, you have much more significant leeway over editing and processing. Preserving image quality, for example, in the case of high-ISO noise, is much easier to do in RAW format, as are correcting color balance and tons of other common enhancements.
Quick Tips for Avoiding Mishaps in Shooting Star Trails
While the above are definitely more essential techniques to take into account, you will also not want to miss the following quick tips.
These can help you avoid seriously frustrating flaws that have tripped up many an experienced astrophotographer, including yours truly!
1. Use Manual Focus
Since you’re shooting against the sky in a star trail session, you would be forgiven for thinking that your focus mode hardly plays a big role. However, that’s not quite the case.
In fact, manual focus presents a distinct advantage compared to any kind of auto-focus when dealing with these kinds of extremely long nighttime exposures. That advantage? Consistency.
Even if you mean to only photograph short star trails – say, not more than 15 minutes of exposure time – autofocus runs the risk of ruining your shot as the slow, gradual movement of the night sky (not to mention intruding foreground elements, clouds, et cetera) throws off your focus lock.
When this happens, your camera will hunt for a suitable point to re-acquire proper focus, but this can take time. And during that time, you will be collecting starlight that’s out of focus, potentially resulting in poorly-defined star trails!
To prevent that, I highly recommend either using single-shot autofocus (AF-S mode) or pre-setting your focus manually. Either way, this guarantees no interruptions and no irregular losses of focus during the exposure.
2. If Shooting with Foreground Elements in View, Go for Your Hyperfocal Distance
Sometimes, you might want to shoot star trail images with part of the foreground in view. Whether that’s to showcase the local landscape, to give a glimpse of civilization by allowing some city lights to enter the frame, or as a matter of pragmatism because your shooting angles are limited by the celestial poles, this presents an obvious problem.
How do you get both the distant star trails as well as your foreground image in perfect focus?
While difficult, there is one technique that greatly simplifies this challenge. It’s called focusing by hyperfocal distances, and it’s a trick that can help you in a wide variety of cases. These are not limited to astrophotography by any means, making it a really neat skill to know!
The hyperfocal distance is, in plain English, the absolute closest you can get to a subject with your lens set to infinity whilst having both that (foreground) object and the background evenly sharp. In other words, it’s a measurement of the greatest possible extent of your depth of field.
Older lenses produced during the manual focus era might actually include engraved indicators to show you what settings to use to achieve hyperfocus. However, on more modern gear made since the 1990s, these markings will likely be absent. That leaves you to calculate the hyperfocal distance by yourself.
The formula for this is not too complicated. Just calculate your lens’ focal length squared, divided by your aperture setting times the so-called circle of confusion. That last figure may be a bit confusing to a beginner, but it can easily be derived from the dimensions of your camera sensor.
3. Level Your Camera
Especially if you are attempting to create circumpolar star trails yourself, it’s important to have your camera and tripod properly leveled against the horizon. Poor leveling can lead to issues with alignment and can make the night sky in your star trail photos look crooked or off-center.
Not to worry, you can correct this alignment in post-processing. Still, it is much more convenient to use a simple bubble level to make sure that your camera alignment is in order before shooting. Some tripods may include integrated bubble levels, which can make the process a bit more streamlined.
4. Consider the Limitations of Your Gear
While it is certainly possible to capture star trails with any setup that includes fully manual exposure, manual focus, and an intervalometer, this doesn’t mean that your choice of camera or lens can’t affect the outcome of your shots.
In fact, it’s imperative to adjust your working style depending on the gear you are limited by. For example, plenty of smaller, entry-level digital camera bodies will not be able to sustain ultra-long exposure times. The resulting hot pixels and overheated sensors don’t just stand to ruin your image quality but might even damage the camera!
In these kinds of cases, you might need to adjust your camera settings for star trails photography with a somewhat weaker sensor. Furthermore, consider power management.
Your camera might not be able to keep the shutter open for, say, 30 minutes or more on a battery that’s halfway discharged. On some compact mirrorless and DSLR cameras, even a full charge might not be good for more than one image or two!
To compensate for that, consider using a battery grip with fully-charged reserve batteries to prevent blackouts. If you’re feeling particularly adventurous, you might even try practicing star trails photography with an older analog camera: no sensor overheating or battery issues to worry about!
An Intro to Image Stacking for Star Trail Photos
For the bulk of this guide, I have been concentrating on the more traditional and straightforward manner of taking star trail images. Single exposure star trails, as beginner-friendly as they may be, do however suffer from a few downsides.
First of all, not all of us can afford to spend a few hours on as little as one very long exposure, which may or may not even turn out well! Particularly if you’re shooting at a crucial time of day (or night), such as just after sundown, shooting only one single image may soon lead to frustration. And then there are the aforementioned issues with overheating sensors and battery problems!
Thankfully, there is a practical alternative suitable for both advanced astrophotographers as well as curious beginners who are willing to step up in their technique.
Called the image stacking process, the principle revolves around composing the same kind of brilliant star trails as you would do in one long exposure but by means of a composite of multiple images taken at much faster shutter speed settings.
Imagine the image stack, if you will, as a sort of photographic time lapse. Taking a series of photos from the same location over the course of a certain time frame, you can superimpose them on top of each other to create a single image of beautiful, surrealist trails.
Stacked star trails look noticeably different from those captured in one exposure. Featuring gaps and unique patterns (formed by the selective nature of the individual shots), they can be even more impressive to look at than a regular star trail photograph.
An Intervalometer is Essential
If your camera does not have an intervalometer for stacked star trail exposures, you will need to use an external, wired solution.
With the help of this gadget, you can entirely automate the number of exposures that your camera will capture, in addition to the timing in between the exposures.
Of course, you may also try to approximate the same thing with a stopwatch and very careful use of a cable-guided bulb exposure, but for the vast majority of us, an intervalometer is the one stress-free option.
Getting Creative with Star Trails
As I said at the beginning of this guide, I think star trails are some of the most beautiful and beginner-friendly gateways into astrophotography.
Even if shooting stars in the night sky is not something you have dabbled in very much in the past, star trails can offer a novel challenge and very rewarding results!
I hope you learned something valuable today about how to approach this stunning photographic niche. Until next time, and have fun shooting!