In this tutorial, we are going to take a look at how to shoot and process a time lapse video of the stars. As the earth rotates, the stars appear to move across the sky during the night, but they move so slowly that the only way to really appreciate this phenomenon is through time lapse footage. We'll cover finding a location, choosing your gear, setting up your camera and doing the post-production.
The Final Result
Location
Shooting starlight time lapse video is really exciting and interesting, but unfortunately you can't shoot it everywhere. If you live in a big city, you'll have to leave it and go at least 40-50 km away because the city produce light pollution. If you try to capture the stars around all that light your images will be blow out because the sky is too bright.
I recommend going and shooting the sky from a mountain far away from big cities. You will have the best chance to capture a nice, clean starlapse sequence. When you choose your location make sure to go there before sunset so you will have enough time to scout the place and choose the best spot for shooting the stars.
Make sure that you have something in the foreground when you frame your shot. Having an object in the foreground helps to give more depth in the photo. It also makes the movement of the stars more obvious. So look for a tree, a rock, an old house or anything that can help improve your shot when you put it in the foreground.
Another thing worth mentioning is that you need to check the weather forecast to ensure that the night sky will be clear without any clouds. Obviously, if you can't see the stars, your time lapse won't turn out very well.
Equipment
You can use a variety of gear for this shoot. I personally shot with my old Canon 550D using a Sigma 10-20mm f/4-5.6, but I regret it now. I strongly recommend using a full frame camera body with fast wide angle lens. Full frame cameras handle high ISO settings much better than crop sensor cameras. In my example, I used ISO 6400 and the resulting noise is terrible. If you don't mind having some noise, or you have one of the latest generation of crop sensor camera, you'll be in better shape than I was.
A fast wide angle lens is also important. For example, the Tokina 11-16mm f/2.8 will be perfect for a crop sensor camera. The difference between f/2.8 and f/4, which is the widest aperture of my Sigma lens, is one full stop which is a lot when it comes to shooting stars. If you are using a full frame body, a 16-35mm f/2.8 will do the job for you. The wide angle lens lets the stars stay in the frame longer allowing the viewer to really follow them.
Once you have your camera and lens, you need an intervalometer to automatically trigger your camera at specific intervals. Some cameras have these built in, but you can find many for around $30 online. Just make sure to get one that works with your camera.
Use a big memory card as well. The card capacity depends of how long you plan to shoot and what format JPG or RAW. I strongly suggest shooting in RAW for maximum quality and post processing options.
Last but not least, you need a nice stable tripod. Keep in mind that it might can be windy. You need to ensure your tripod is as low and stable as possible.
Camera Settings
When it comes to choosing settings for you camera, you need to balance a few things. First, you want to let as much light into your camera as possible to get a good exposure for the stars. You do this with a wide open aperture, a slow shutter speed an a high ISO. Two of these things are easier to determine that the last.
Set your aperture as wide as it will go. We're using a wide angle lens focused at infinity, so your depth of field will be deep regardless of what aperture setting you choose. Next, set your ISO as high as possible without introducing an unacceptable amount of noise. This will vary from camera to camera.
Setting your shutter speed is the most tricky because you need to let in enough light, but you also need to keep your exposures short enough to eliminate the appears of star trails. If you leave your shutter open too long, the stars will appear to be lines instead of dots, and we don't want that.
There is a formula known as "the 500 rule" to calculate how long you can expose without getting star trails. The formula is 500/the focal length of your lens = amount of seconds you can expose without getting star trails. For example a full frame camera using a 16mm lens, the formula is 500/16, which equals 31 seconds of exposure time. Exposing for this amount of time or less will keep the stars looking sharp and round.
If you're using a crop sensor camera, then you need to convert your lens focal length a 35mm/full frame equivalent before doing the calculation. In my case, I was using a 10mm lens, which is equivalent to a 15mm lens on a full frame camera. Using the formula, I could expose the image for 33 seconds without getting trails.
Once you have this number, you have a place to start your exposure. Take a test shot and see where you're at. If you image is overexposed, adjust your ISO lower or make your shutter speed faster. If your image is underexposed, you'll have to sacrifice image quality and bump up your ISO.
The next thing you need to set is the interval on your intervalometer, essentially the time between photos you're making. Keep in mind that you already have a built-in gap due to your shutter speed, in my case almost 30 seconds. So, I would suggest keep your the gap very short, maybe one or two seconds just to give your camera time to process and save your image to your card.
Your final concern should be your white balance. Shooting against a dark background in a situation without many white tones will cause your auto white balance setting to fluctuate. You'll want to use a manual Kelvin white balance setting. I would choose something around 5500K. You'll be able to adjust your white balance more precisely during post-production, but the goal while shooting is consistency so you can process your first image and apply those settings to all your other photos.
Post-Processing
Once we are ready with our time lapse, we are going to download all the files to a computer and jump into Adobe Lightroom to process the sequence.
Once you have the processing for your first image done, click the Copy button on the left side of the screen. Make sure you have all the areas you made edits in checked off, then click Copy at the bottom of the dialog box. Next, select all the images in your film strip except the first one you made edit to. Then, click the Paste button on the left side of the screen to apply your edits to all the images in your sequence.
Finally, switch back to the Library module and export your series of processed images.
Creating the Video
There are dozens of ways to turn sequence of images into a time lapse video. You can use Photoshop, Final Cut Pro, Avid, After Effects, Quicktime, iMovie and many other programs to get the job done. Essentially, you're turning each image into one frame of video.
For example, in iMovie, you just follow these steps.
Create a new project
Click the Camera Button on the right side of the window
Find your folder of images, and drag it to the timeline in the upper left area of the screen
Click the clip to bring up the inspector window
Change the clip speed to anywhere from 200 to 2000 percent. You may have to manually type in percents over 800.
View the video and adjust the clip speed until your video the right length and looks smooth.
Export the video.
Even in iMovie there are many different ways to make a make a time lapse. Just decide what program will work best for you and do a little homework.
The Finished Video
I'd love to see your starlight time lapse videos. If you have a chance to make one, please leave a link to it in the comments!