I’m not a big astrophotographer, the sky is just too bright here most of the time. I’ve dabbled in it here and there, but never anything serious. However, I recently found myself in possession of the Irix 15mm f/2.4 lens (review coming soon). With a lens of this width (field of view) and width (aperture), it was created for astrophotography. So I experimented again.
So this video by YouTuber Josh Katz comes at just the right time for me. He, too, says he’s not an expert at photographing the night sky, but he knows enough to explain the basics and get you started. Like me, Josh lives in an area where the constant struggle is to find a sky dark enough to actually be worth photographing. But he also gives a few tips for that.
- 1:20 gear you need
- 2:52 light pollution + sky mapping
- 4:20 Step 1: Setup + Locations
- 5:10 Step 2: Composition
- 6:08 Step 3: Alignment (Basic Camera Settings)
- 6:42 Step 4: Aperture
- 7:28 Step 5: Shutter speed
- 7:56 Step 6: ISO
- 8:25 Step 7: Focus
- 9:09 Step 8: Experiment + Verify
- 9:58 Step 9: Lighting the foreground subject
- 11:12 Step 10: Refine your recording
- 11:38 Step 11: Editing in Lightroom
The video is aimed at those who don’t live near dark skies and don’t often get the chance to shoot something like this. Josh talks gear first, and you don’t need anything so fancy. However, you may need to think carefully about your camera choice. You want something that gives fairly clean results up to around ISO3200. Josh uses a Canon EOS 70D.
In general, you need a wide-angle lens for astrophotography, especially as a beginner. This is because the earth is moving. A lot actually moves in the time it takes for an exposure of 15 or 30 seconds. The Irix 15mm lens on my Nikon D800 has a field of view of around 100°. But even so far, at a 30 second exposure, I’m starting to see the stars stretch a little.
For the same reason, you need a lens with a fairly wide aperture that lets in as much light as possible. This way you can keep your shutter speeds faster to reduce that blur caused by our beloved little planet’s rotation. Josh uses the Tamron 10-24mm f/3.5-4.5 zoom, which he admits isn’t really fast enough, but it works for him. If you have a camera with suitable ISO performance, it might work for you too.
Other options include the Rokinon/Samyang 24mm f/1.4. Personally I don’t think the wide angle is enough for my own taste and the stars move faster across this frame due to the narrower field of view. But a maximum aperture of f/1.4 means the shutter can be open a quarter of the time it would take you with an f/2.8 lens. If you need 30 seconds with a wide open f/2.8 lens, you need only 8 seconds with an f/1.4 lens. So less movement from the stars.
You also want some accessories. A good sturdy tripod is a must as you’re unlikely to get good 15-30 second or longer exposures handheld. A headlamp or flashlight is also very useful. In a pinch, you can use your phone’s LED light. Personally, I was finally able to put my Aputure Halo to good use. I just put it on a light stand with a regular flash mount.
An intervalometer helps, but is not essential. Even if you don’t actually do time-lapse photography, these can work well as remote shutter releases. I use the Yongnuo MC-36R wireless intervalometer. In this way, no physical movements of mine when I press the shutter button are transmitted to the camera or the exposure. However, where an intervalometer can really come in handy is when you want to do star trails. But that’s a whole different topic.
I also activate what Nikon calls “exposure delay mode”. This flips the mirror up and then waits a short while for all movement to stop before starting the exposure to avoid vibration. If you don’t have an intervalometer or remote shutter release, you can use your camera’s built-in self-timer.
Once you’ve got your gear sorted, the next step is to find a location. Josh lives in DC and goes to school in New York. Both are fairly well-lit places. Therefore, it can be difficult to find dark skies in the immediate area. So you might have to travel an hour or two (or more) to find a suitably dark spot. One of the absolute best places on the web to find suitable filming locations is darksky.net. They also have an app for Android and iOS so you can keep an eye on the sky while you’re out and about.
It’s usually a good idea to show up at your chosen location before it actually gets dark. This allows you to set up your composition while still being able to see. So, now comes the shooting info. First, it’s crucial that you shoot raw. Even if you usually shoot JPG, this is a time when you really want to shoot raw. Most of our DSLRs just aren’t built for this type of photography and you won’t usually be able to pull out that star detail while eliminating noise from an 8-bit JPG.
You should set your exposure mode to full manual and turn off auto ISO if it’s enabled. The first setting to clarify is the aperture. You should keep these as low as possible to let in as much light as possible. Be warned, however, that on some lower-end lenses, the wide-angle opening may not be particularly sharp. Some lenses may not be perfectly focused at infinity when they should be. So use live view to point to a star and check if it’s sharp.
Once the aperture is set, the next step is shutter speed. This depends on the focal length of your lens. A common rule for astrophotographers is the “500 rule”. Essentially, 500 divided by your focal length gives you the maximum number of seconds you should have your shutter open. So for example with the Irix 15mm f/2.4, 500 / 15 = 33.3. Although even after 30 seconds I could see those stars starting to shift a bit if I looked really closely. However, 15-30 seconds is usually about the standard.
Finally, you want to set your ISO. You should keep it low enough to keep noise to a minimum, but high enough that your camera can actually see the sky and pick out the faint distant stars. ISO 1600 is a good starting point. You can adjust it up or down from there depending on how bright the sky and stars are with your lens’ aperture. For example, with an f/1.4 lens you can use a much lower ISO than with an f/2.8 or f/4 lens.
Now all you have to do is take a few shots and adjust these settings. Then experiment. Try adjusting your shutter speed or ISO to see how it affects the number of stars you can see. Push the limits of your ISO, you will be surprised.
If your scene also includes some land or foreground (hint: there should probably be scale and context), you can try light painting. This allows you to bring your scene to life with the stars as the background instead of just showing them in silhouette.
Back home it’s time for post-processing. You’ll probably want to play around with the white balance here to get something that feels right. While the sky often looks like pure blackness to our eyes, this is not the case to the camera. The long exposure camera captures all sorts of colors that our eyes aren’t sensitive enough to see. But it’s up to you to decide whether you want these colors to be warm or cool.
And that’s pretty much all there is to it. Once you’ve disassembled and tried it out, there really isn’t much on the basics of astrophotography. After that, many methods of improvement boil down to simple old experiences. The more you go out and experiment, the more mistakes you make, the more you learn for next time.
It’s a process Josh is still learning and one I’m still learning too. I definitely saw a few surprises where scenes were a lot darker or lighter than I thought. Some skies that I thought were fantastic have turned out to be awful, while others have turned out to be much better than I expected.
What other astro tricks and tips can you suggest?