How to shoot star trails
Top tips that will get your world spinning
What kind of mad man hikes up into the mountains in the deepening twilight, only to sit for an hour half way up a mountain, shivering with the cold as the temperatures plummet under the clear skies above?
The kind of mad man who gets likes to take time out from the manic busyness of life just to lie back and stare up at the stars above for an hour, watching our planet spin its way through the cosmos, that's who. Oh, and to shoot a set of shots to make a star trails photo in the process!
After spending an hour the other night perched on the flanks of Slieve Binnian, I thought I'd share with you how you could capture a shot like this for yourself.
If you'd like to take time out to star at the stars - and to get a cool star trails shot in the process - read on!
1. The gear you will need
A camera that allows manual control e.g. DLSR or a mirrorless camera (although many smart phones have a star trails function these days too).
A sturdy tripod - you'll be taking shots for about an hour, and any movement in your tripod over that time will ruin your final photo.
A wide angle lens - to get as much of the sky in as possible and to get as big a spin of trails, you'll need to go as wide as you can - preferably at least 12mm on a crop sensor camera or 16mm on a full frame.
Intervelometer - this will allow you to take shot after shot without having to touch your camera (again important for maintaining the camera position, as well as allowing you to lie back and look at the stars!). Your camera may have this built in; if not, you can buy a cable release that will allow you to do this too.
Well charged batteries
Warm clothes - you'll get cold sitting around for an hour!
2. Setting up your camera
i. Put your camera on full manual mode
ii. Focus on a bright light source far away and turn your camera on to manual focus
iii. Shoot in RAW
iv. Set the aperture first
If it's a Moonless night, it'd be best if you had a lens with a wide aperture - at least f/2.8 is preferable - to allow yourself to capture lots of light.
If the Moon is out, a narrower aperture would do, but don't go much above f/4 as you don't want your image to be too dark.
v. Set the shutter speed to 30 seconds.
You are shooting for more than 30 seconds, so why 30 seconds? Because if you shoot for much longer than that, your sensor will heat up and you will start to get spots of white on your image which are caused by the overheating of the sensor. Lots of 30 second exposures are better than one exposure of 15 minutes. Additionally, 30 seconds is the maximum your camera can shoot before going on to bulb mode, so 30 seconds will allow you to sit back and enjoy the view whilst your camera does all the work!
vi. Set the ISO after this and test your exposure
Start around ISO 2000 or so and see how the photo comes out (different cameras handle higher ISO settings differently, so you'll have to experiment and see what's best for you).
vii. Check your histogram to make sure the exposure is okay
Don't rely on your eyesight and the image on the back of the screen. Your eyes will dark adjust and the backlit screen may mislead you into thinking that your exposure is okay. But, when you load it into your computer when you get home, you may well find out that it's too dark. Make sure the histogram isn't too bunched in to the left (too dark) and watch out for highlghts that may be blown.
3. Taking the shots
Framing the composition is vital in star trails shots. Because, once you've started, you cannot move your camera for the next hour! So it's worth experimenting with a series of test shots to make sure you've got it right.
i. Get your foreground set up pleasingly, with the elements composed as you would with any photo.
ii. Then think about how you want the stars to be placed. In the Northern Hemisphere, the stars spin around Polaris (the North Star). You can find it by locating The Plough and following a line up from the two stars on its rght. Move up along this line, and the next bright star you come to (just slightly off this line) is Polaris. If you include it in your shot, it will remained fixed, and the rest of the stars with spin around this like a celestial vortex.
This is where the wider angle lenses come in handy - getting the ground and Polaris in the shot can be tricky without them. If you don't have a wider angle lens, think about doing a portrait oriented shot.
iii. Once you're happy with your composition, set your intervelmeter up to take about 120 shots. At 30 second exposures, that's an hour's worth of shooting, long enough to make for decent length star trails.
iv. Then, let your camera do all the work for the next hour. Your job now is to lie back in the darkness and gaze up into the skies above, and let your imagination run riot as you think about the 100 billion stars in our galaxy alone, never mind all the other billions of galaxies out there. Moments like this are good for the soul, I can tell you...
4. Post production
When you finally get home and warmed up, the next stage is putting the fruit of your labours all together.
i. Batch process your shots in Lightroom (or some equivalent software). Work on a single shot to address things like:
Bringing up shadows on the foreground
Perhaps adding a darkening gradient to the sky to bright out the contrasts so that the stars pop a bit more (this will depened on your overall exposure, and will probably be more necessary if you shoot on a night with lots of moonlight).
ii. Once you've exported them as jpgs, then you can use a program to make the star trails for you. the one I use is Starstax - it's free, easy to use, and it does that one job very well. Simply drag the images in and watch the stat trails appear before your every eyes. Hey presto, and your work is done!
5. Time lapse video
Or, maybe not quite! One of the added benefits of shooting 120 images is that you;ve got a bunch of images that you can put into the likes of Moviemaker and produce a time lapse video, showing the stars spin. In fact, you can get Starstax to output a photo each time it adds a new shot you've taken (rather than just one single image at the end). So not only can you have a time lapse video of the stars spinning, but you can get the trails to appear before you too. All you need is some suitably epic music as a backing track, and you're ready to be the next Steven Spielberg!
So there you have it. Now you're all set to join this mad club with us astro photographers. To get cold, to be out late - and to have the chance to lie back and gaze off into the eternal wonders of the night sky for an hour. Who needs feeling in your toes anyway...?!?