ISS & BIG DIPPER OVER COTTON CANDY SKIES
Image Credit & Copyright: Me. CLICK image for larger view and look below for information and related links.
Here’s a quick shot of the ISS that I grabbed tonight and I figured I would show it off and tell you how I did it at the same time…….so why not?
Ok, so as I start every night when I plan on catching the ISS, iridium flares, the secret USAF X37B spacecraft, Hubble, Tiangong 1 or any number of the dozens of nightly bright satellite passes I start with the Heavens-Above website (link below). All you do is make a free user ID and it will tell you when anything will be flying over your head from your location, from which directions, at what times etc. If it’s just the ISS you’re looking for there are many places to look for times, maps, real time tracking etc. I put some of the best ones on this list: https://danspace77.com/iss-tracking/
For starters, I have an old school Nikon D90, a cheap $40 box store tripod and the invaluable intervalometer (a simple cable release will work just fine). I used the cheap f3.5 18-105 mm lens that came with the Nikon kit so nothing fancy here (yet). I have some quality lenses but my sky is just too bright to bother using them at home. So check whatever medium you like to use for accurate flyover times, get your photography stuff together (don’t forget the memory card and fresh battery) and get outside, assuming the weather is cooperating.
I shoot from the back porch; this is almost never recommended as even the slightest movement of your feet will ruin the entire shot. 1: I’m pretty good at being perfectly still. 2: As I said before, my sky is bright and horrible so in the end I don’t care if I blow the shot.
OK, so tripod up & level, camera attached and shutter release cable plugged in. The shutter release cable allows you to shoot in BULB mode and also ensures that you don’t vibrate the camera at all having to manually push the button. The first thing I do after turning the camera on is find focus. To focus just set the lens to infinity OR zoom all the way in as far as you can on the moon or a planet and fine tune your focus. If you don’t have the moon or a planet handy, just use a bright star like Vega, Arcturus, Sirius, etc.
Now for the settings; first, were always shooting in full manual so set your camera and lens to manual. Also if your lens has vibration reduction (VR) setting, turn that off too. As far as the aperture, I just put that on the fastest F-stop I can get (that’s 3.5 for my basic lens at 18mm). Now go into the camera and turn off the internal noise reduction. This is a must for long exposure photography. You won’t want to take a 30 sec to 1 minute or more exposure just to have to wait that long after for the image to process in the camera while the ISS is getting away. When you turn off your internal NR you can take the next pic as soon as the current one ends without interruption. With my bright sky, the longest I usually go is exposures of 30 seconds. Ideally you want to shoot with a very high ISO to collect as much light as possible but again, where I live shooting at ISO 3200 means a white image after 10 seconds. Sadly, from my back yard I shoot at an ISO of 350 to 200 depending on the night.
Our physical setup is in place; our internal settings are in place, you’ve done your homework on what it is you want to shoot; now finally you want to take a few test shots with your basic settings in place. See what the sky is offering you that night because it does change, make tweaks and adjustments if needed then when you’re ready, place the camera in the direction where you want it to be when the ISS (or whatever) appears and BE READY!
As far as the shot that I took; it was three-30 sec exposures at ISO 350, F3.5 at 18mm. I stacked the images together in the free “Startrails” program online and that was it. You can tell in the full size image that even at 1:30 worth of exposure at 18mm there are some pretty long star streaks. That’s unavoidable when taking long exposure images like this. Anything over say, 30 sec at 18mm you will readily notice star streaks in the image and it you track the stars then the object you’re shooting will be off. If you want crystal clear stars you should be using the “500 Rule” where you take 500 and divide that by your focal length to determine how long you can shoot before star trails begin. So for me, shooting at 18mm would be; 500/18mm = 28 seconds. It’s actually 27.7 but oh well. That’s pretty much what I did but the three exposures brought the total image time to 1:30 and completely busted the 500 rule. For me, the long stretching laser like view of the ISS through the night sky was a fair trade for some minor streaking. Alternatively I could have just posted one-30 second image but the ISS would only stretch 1/3 of the picture and I like this much better. Ultimately there’s other things you can do to get rid of the streaking like copying the combined 1:30 ISS trail and add it onto a single 30 sec image (which I may do later) or you could painstakingly go through every star in the image and re-shape them (no thank you).
You can get into shooting dark frames as well then add them into your image stack during processing which helps reduce noise in the image. To shoot “darks” just place the lens-cap back on the camera and take some more shots in the same temperature and at the same image length.
So let me know what you think. This is very basic night sky photography and after you do it a few times you will be hooked and imaging everything you can think of. Anyone have any different techniques? Let’s hear em!
Heavens-Above (Free): http://www.heavens-above.com
Startrails Program (Free): http://www.startrails.de/