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The International Space Station is an inspiring sight. If you’ve never spotted it cruising across the night sky, have a look at 3 Easy Tools for Spotting the ISS to find out when it will be visible passing overhead. (If you live in the UK, follow @VirtualAstro on Twitter for regular updates on passes there.) If you want to go one step further, there are two different ways to photograph the ISS as it passes overhead.
I’ll talk about the easy star trail method first. The more difficult method, a close up of the space station, is a great challenge for anyone with a telescope and a prime focus camera. While I’m specifically talking about the ISS in this article, the same methods can also be applied to other sun-lit satellites.
The Easy Way
If you search Flickr or Google for ISS Photos, most of the results you see (aside from NASA images) will be of the star trail type. This is incredibly simple to get started with. But don’t think that every star trail, or station trail, looks alike. As you gain a bit of practice and experience, you can create some inspiring landmark images with the ISS passing overhead.
- A Camera with a variable shutter control. Most point and shoot cameras will work for this, but most smart phones won’t. (I used a Canon T3i for the shots here.)
- A tripod to hold the camera steady.
- I also recommend an intervalometer if you are using a DSLR.
First, figure out when the ISS will be passing overhead, and what path it will take through the sky. ISS Spotter on the iPhone is a great resource to figure out the times, how much of the pass will be sunlit, and how bright it will be. Websites to check can be found in 3 Easy Tools for Spotting the ISS.
Now that you know when you’ll be snapping your photo, you need to know exactly where in the sky. The free planetarium software Stellarium can be setup to show you the path the ISS will take. If you have an iPhone, Star Walk or Sky Safari will show the path of the station as well. Neither of these products will tell you when the station is sunlit (visible) vs. when it will be in shadow. That’s another reason to look at the ISS Spotter first.
In Stellarium or Star Walk, you can make note of which constellations or other objects the station will be passing close to. This will help you compose your photograph. Depending on the focal length of your lens, you might want to capture the station as it passes a particular constellation. You may also want to frame the station trail against a terrestrial landmark. That could be a stand of trees, the roof-top of a house, or even a cityscape. How you choose to frame your shot is what really makes it unique!
Note: The angle and details of each station pass are different, so you need to make sure to check separately for each pass you want to photograph.
Once you’ve composed your photo, you want to set your camera to take at least a 10 second picture. The settings you use will be different between cameras, and how much light pollution you have. You can do a single exposure (the ISS with the trees is a single 15 second exposure) or if you have bright objects, you can do a series of shorter exposures and stack them together later (as I did with the space needle shot).
IMPORTANT: Before the ISS passes over, test out your camera settings. Do some trial exposures to make sure the image isn’t getting blown out (from too much light), the ISO isn’t too low (stars are very dim and few) or any other little problems. If you do a series of exposures to stack, you also want to make sure you turn off Long Exposure Noise Reduction in the camera settings. Otherwise, you’ll have a gap between each image.
The Hard Way
Up for a challenge? The ISS moves across the sky in about 5 minutes, but many passes are only sunlit (visible) for 4 minutes or less. That’s from one horizon to the other in a matter of minutes! So, how do you get a close up of the space station? Well, luck does have something to do with it!
Equipment Needed: (See the Deals on Gear page for current bargains)
- A telescope with a long focal length (over 800mm, ideally much longer)
- A DSLR camera mounted prime focus to the telescope. (See The Best DSLR Cameras for Astrophotography)
- Ideally, a Barlow that can be mounted between the camera and telescope to further extend the focal length.
- An intervalometer.
Most telescope mounts can’t track the ISS – it just moves too fast. The way I was able to photograph it was manually moving the telescope following the ISS in the sky, and taking pictures like mad! To get the image below, I basically waited for the ISS to appear with the telescope pointed at that point, and the clutches on the mount loosened so I could maneuver the scope manually. The camera was set to ISO 1600, and just 1/1600th of a sec exposure time! It has to be a short exposure, because I’m manually guiding a 1500mm lens, and there is no image stabilization. Looking through the finder scope, I’ll follow the bright dot of the ISS as best I can manage, and just hold down the shutter button on the intervalometer to fire off as many pictures as I can get. Most of those were misses – no space station. Some of them were however hits! Some of those hits were a bit too blurry, but a couple came out clearly enough to start identifying parts of the ISS!
The slightly easier, less cumbersome method would be use one of the aforementioned astronomy apps to trace the path of the ISS in detail against the background stars such that you can find a point in the sky to point your telescope at, that you know the ISS will pass across. Then as it approaches, start firing off exposures!
If you really plan ahead, and depending on your location, you might be able to snap the ISS passing in front of the moon or even the sun (with an appropriate solar filter!). I have yet to be able to pull off that trick.
The brighter passes are best (usually about Magnitude -3). Given how short an exposure you need to be able to take, getting the station at it’s brightest if going to offer a better image.
How big is the ISS through a telescope?
The moon is about 30 arc minutes (about 1/2°) in diameter. The ISS is about 30 arc seconds (about 1/60th the diameter of the full moon). Of course, the ISS isn’t a nice round shape. In practice, it will appear a bit smaller – probably about the size of Saturn or Mars, depending on where they are in their orbits, and what inclination and orientation the ISS pass happens to be. The gist is, it’s a small, fast moving target.