I have always enjoyed a challenge, it's just the way I am. So when I saw images on the internet of the International Space Station (ISS) crossing in front of the sun I was intrigued, I wanted to capture an image like that. How hard could that be? Well, it's not easy, but it can be done, even by someone with just basic photographic skills, if they have access to the right equipment and have a good sense of adventure.
In this installment I will talk about the kind of equipment you are going to need, in part two I'll talk about getting to the right location and how to judge the best pass to shoot. Part three will be about the specifics of capturing the event, and tips on how to optimize your chances of success.
First off, let me give you one VERY IMPORTANT piece of advice - if you are going to attempt to shoot a satellite crossing the sun DO NOT EVER, EVER, EVER look directly at the sun without a proper solar viewing filter, DON'T DO THAT. Have I made myself clear? That brings me to the first and most important piece of equipment for photographing the sun - a solar filter.
With a very special solar eclipse coming up on April 8, 2024 there will be lots of people on the internet trying to cash in by selling "eclipse viewers" and the like, be very careful if you are thinking of buying these, don't risk your vision. One good place to get eclipse viewers and solar photography filters is Thousand Oaks Optical - http://www.thousandoaksoptical.com/solar.html. These folks have been in the business for many years and know what they are doing. There are others suppliers out there, just do your research. Remember, viewing the sun without proper protection for your eyes and camera can cause permanent damage and blindness.
There are two versions of basic solar viewing filters, photographic and visual. The visual filters are lower optical quality than the photographic version, meaning the filter may not be optically consistent across the filter. That inconsistency would not be visible in the eye, but would cause variations in exposure in a photograph. Visual viewing filters are usually made of a thin mylar film, the photographic filters can be either mylar or glass. You can use either one, but you will get the best images from the photographic filter. Just make sure you get one that is a good fit for the lens you will be using, and ALWAYS have the filter in place before you point the camera toward the sun.
Next piece of equipment is your camera. This can be either digital or film (remember film?). In a perfect world this camera would be capable of shooting multiple frames per second, the faster, the better. Why you ask? This is where it gets interesting, most photographable satellites move at a very high rate of speed, at least 17,500 miles per hour, that's orbital velocity (28,164 kilometers per hour). For an example of how fast that is, it takes the ISS about 1/2 second to cross the face of the sun. If your camera does not shoot fast enough, you may miss the shot.
Some digital cameras have the ability to shoot video, this is really the best way to capture this fleeting moment. The image at the top of this page was captured on video at 24 frames per second in 4K mode with a Canon 1DC. I then stacked every frame that contained the station to obtain the final image (there are 13 of them).
The resolution of you camera will play an important part in how much detail you will record, the more pixels the better, especially if you don't have a super long telephoto lens or telescope.
I'll talk more about how all this comes together in part three.
Next you are going to need a telephoto lens, the longer the better. For the space station/sun photo above I used an Canon 800mm f/5.6 with a 2X tele-extender which gave me a solar disk image that very nearly filled the full frame sensor of the 1DC. You can also use a telescope to capture transits if you have the proper camera adapter. Just remember, if you are shooting solar transits you MUST have a proper solar filter suitable for the optics you are using. You can destroy your camera if you attempt this without the proper filter. Never look directly at the sun without a solar filter!
You will need a sturdy tripod to support the camera. Trying to shoot this with a handheld camera is not a recipe for success. I use tripods designed to hold very heavy motion picture cameras, like the one pictured to the left, but any heavy duty tripod will do. It is important to make sure the tripod head will allow you to point the camera straight up. If you are using a telescope it should have a fairly sturdy support system as a matter of course. If the telescope can track the celestial body, so much the better, you won't have to be constantly re-centering the subject as the earth rotates.
There are a couple of things that are not required, but sure are nice to have when pointing a camera with a long lens at the sky. I use a small portable LCD monitor that I hook into my camera with an HDMI cable. The monitor allows me to see the image without having to physically look through the camera. This makes framing and focusing much easier, as you don't have to stand on your head to look through the viewfinder or see the screen on your camera. Of course, if you're shooting film you won't have this option. More on focusing and framing in part 3. A remote shutter release of some sort is also very useful, especially if you are trying to capture the event in still mode, the release isn't as important when shooting video. Having your hand on the camera to press the shutter release button will induce movement into the camera which can cause a blurry picture. Shooting video you can start the camera recording well ahead of the event time, this allows any vibration to dampen out in time for the shot.
That's about it for the hardware you'll need. It sounds like a lot of stuff, and you may not have access to all of it, but there are several reasonable rental places that will have what you need at a reasonable price. A few of them are: www.borrowlenses.com/ www.thelensdepot.com/ and www.lensrentals.com/ or just do a web search for camera equipment rentals.
Coming up next in PART TWO I will talk about how to get to the best location for a crossing, what to look for in a crossing opportunity, and some apps to make things easier.
Till next time, keep shooting!