Photographing the International Space Station is no easy feat. It takes skill, a fair amount of planning, and a whole lot of patience. After years of planning, Aaron Harris has managed to perfect his method for capturing the ISS in transit. Aaron uses his Canon 7D with a Sigma 150-500mm, and of course his Triggertrap kit, to capture his stunning images. We got in touch with Aaron to find out how he captures his impressive ISS photos.

Step by step

1. Go CalSky’s ISS page, and enter your location and time in the upper right hand corner. After you’ve set your location, go back to the ISS page and change the “Duration” to 10 days. Anything longer than that is inaccurate for both time and location. Next change “Maximum distance to center line” to the distance you’re willing to travel. For me it’s 100km. Now click “Go.”

2. Once the page of ISS passes loads, search for a pass that says “Close to the Moon” or “Close to the Sun.” This is what you’re looking for. Find “Centerline” in underneath and click it.

3. This map shows a line which represents where the transit is visible. Find the most convenient location you can as close to the centreline as you can. Parks, parking lots, etc.

4. Click on the red square on the centreline and that will tell you the exact time that the transit will occur at that location. Take note of the “Path Width”, as that’s how far from the centreline the transit is visible.

5. The day before the transit, I’ll edit my script and the cron job and test everything out. If you aren’t comfortable using cron or command line utilities, I highly recommend bribing your local Linux geek with some craft beer for assistance. (Take a look here for Aaron’s script and cron job.)

6. The day of the transit I plan to arrive at the location at least one hour ahead of time. I do this mainly so that if the first location doesn’t work out, I can travel to the backup. I also pack all my gear:

• Milk Crate
• Manfrotto 055X PROB Tripod with 498 RC2 ballhead
• Pelican 1510
• MacBook Pro
• Canon 7D
• Sigma 150-500mm
• Kenko 1.4x teleconvertor
• Triggertrap Mobile Kit
• 6′ 3.5mm mini-jack extension
• USB cable
• Business cards
• DIY Solar filter (an astronomy professor made me a solar filter made from PVC pipe, duct tape, and Baader Solar Film)
• Clipboard with printout of CalSky page

7. Now it’s a matter of setting everything up. I focus manually and use Canon EOS Utility to achieve better focus. I set the camera to manual and use 1/1600s as a starting point for setting exposure. If the exposure is slower than 1/1600s the ISS will be blurry. These are the settings you need to make sure you have set:

• 1/1600s or faster shutter speed
• Live view or Mirror Lockup
• High speed burst mode
• PowerSave or Auto-Off to Never
• Just like on the Triggertrap app, the volume must turned up to maximum on your computer.

8. T minus 10 minutes: I always check the script one last time and set the camera to live view to cut down on mirror slap.

9. Now is just a matter of sitting back and hoping that the clouds don’t roll in at the last second and your calculations were correct. Best of luck!

Check out more from Aaron

To find out a little bit more about Aaron, check out Trigertrap’s Q&A with him! You can see more of Aaron’s astrophotography over on his Flickr page, and Instagram. For more of his tips and tricks head over to his blog. For ISS predictions specific to Bowling Green, Kentucky take a look here. This article was also published here and shared with permission