Filming an ISS Transit of the Moon

by Sean Setters

Bruce, a site visitor, forwarded us a post by weather.com – ISS Crosses in Front of the Moon Captured in Rare Video. Coming across the weather.com post, Bruce had been reminded of an article we posted 2 years ago offering tips for photographing the International Space Station as it crosses the moon. And after seeing the video, I was eager for my own opportunity to film the ISS transiting the moon.

As luck would have it, an ISS transit of the moon visible from a location near me (about 1/2 mile away) was scheduled to occur the very next evening at 10:44 PM Eastern Time. With a calendar entry set to remind me an hour before the event, I was ready to narrow down what gear to take.

As the Canon EF 300mm f/4L IS USM is the longest telephoto lens I own, using it was an easy choice. But my previous experience photographing an ISS transit with a 300mm lens left me wanting for a longer focal length/closer view. Since then, I had picked up two key pieces of gear that would help me get a more magnified view of the moon in my video – a Canon EF 1.4x II Extender (predecessor to version III) and a Canon EOS R.

But how would an EOS R help me get a more magnified view? The 4K crop factor (1.75x), a bane to those who desire ultra-wide angles of view, is a big benefit when one is focal length deficient for a particular endeavor. The setup left me with a manageable 725mm equivalent focal length (300mm x 1.4 x 1.75).

Unfortunately, a limitation of utilizing 4K for capturing the event would be the 30 fps frame rate. I seriously considered setting the camera to high frame rate recording (120 fps), but the camera can only record at a max resolution of 720p in that mode and movie cropping (to provide a similar magnification) is unavailable. In other words, I was faced with a choice of either capturing high resolution video at a higher magnification or lower resolution video at a lower magnification but with a 4x faster frame rate (useful for creating a slow-motion effect). In the end, I opted for shooting in 4K to record the moon as large in the frame as possible with a resolution that would enable me to scale the video with decent quality.

Because it was so close to my home, I arrived at the shooting location only about 15 minutes before the event. I set up my Induro tripod, attached the EOS R to the tripod's Arca Swiss Z1 ball head, and proceeded with adjusting the camera settings accordingly. Up until that moment, I hadn't yet decided on what shutter speed strategy to use. Typically speaking, your shutter speed should be set to a reciprocal of double the frame rate (for 30 fps video, a 1/60 sec is optimal). However, I at that time I wasn't absolutely certain that I wouldn't want to slow down the 30 fps video a bit in post. Knowing that the transit would occur very quickly, I was concerned that if I did slow down the video, the ISS's fast motion would leave little of its detail remaining if using a 1/60 sec shutter speed. However, using a much faster than twice-the-reciprocal-framerate shutter speed can lead to an unnatural look. In a spur of the moment decision (and with transit time quickly approaching), I set my camera to the following settings to gain the desired exposure while maintaining a near multiple of my 30 fps frame rate: f/6.3, 1/250 sec, ISO 100.

About a minute before the transit was scheduled to take place, I hit the record button and anxiously awaited the ISS's crossing. Roughly a minute after the event time, I stopped the recording. Even though I had been watching the moon throughout the recording, I never saw the transit take place until I was processing the video in Premiere Pro a short time later.

And speaking of processing, I actually produced two versions of the video. The one below is the first option I produced. The ISS's fast motion and shape reminded me of an Imperial TIE Fighter from Star Wars, so I thought the dramatic music seemed appropriate:

However, knowing the cinematic-style music may not be for everyone, I created the second version (featured at the top of this post) with different music. I recommend watching the embedded videos full screen on the highest resolution setting using the largest display available to you. Otherwise, you may not be able to see the transit in the normal magnification portion of the video.

So which version do you prefer? Let us know in the comments.