18. How to Take Photos 14: Night Skies & Stars
This lesson comes from information provided by Alyn Wallace and Simon D'Etremont:
The Best Time to Shoot Night Skies
There is a season for shooting the Milky Way. In the northern hemisphere, it starts in spring and extends through the summer and into fall. This is when the core of the Milky Way is visible. You should also check your lunar calendar, and find which days have a "new moon" - in other words, no moon present in the sky. These darkest nights will have the least light pollution, so you can see all the other, fainter stars twinkling brightly. After that, check for the time of sunset, and schedule to get there much earlier. Hopefully, the skies will be clear of clouds (a couple won't hurt). Simon recommends using PhotoPill, an app that tells you about the exact position of the Milky Way as well as sunrise and sunset times.
Location
You need to find an area far from town, devoid of city lights, street lights, highway lights - any kind of light. Do a Google search or ask your local photo experts for good locations. You can also use websites like lightpollutionmap.info. If you do, you'll see that much of West Virginia lies in the darkest region available on the west coast:
You want to find some place with a big open field, a great view of the sky, and something pretty in the foreground as well. Simon here recommends rustic settings, old barns, old cars, nature, and bodies of water, which cast great reflections on a still night. Simon also recommends to get to your location during the day and scout around for the best compositions. If you want to capture the center of the Milky Way in your shot, you'll want to look for compositions facing south.
What You Need (Recommendations):
1. Flashlight: You may need a flash light to find your way in the dark.
2. Your camera - full frame cameras work better for this, as they have a larger sensor that can take in more light.
3. Lens: wider is better. The wider your lens, the more light you can take in, and the more sky will fit in your composition. Wide lenses also reduce "star streaking". You also want a "fast" lens, meaning any lens with a great big aperture (a super small f number - f/2.8 or smaller). This also lets in more light, for shorter shutter speeds and less streaking.
4. Tripod - this is crucial for slow, night time shutter speeds.
5. Remote Control Shutter Release (also called an intervalometer) - if you press the release button on the camera itself, you'll shake it, which can make your photos blurry.
6. Lens Warmer - this is a velcro pad, kind of like a scarf for your lens, to keep condensation from building on the lens.
7. You may be able to get an extra battery pack that plugs into your camera, through the terminal, to give it extra power. It depends on the camera.
Camera Settings
1. Turn down your LCD screen brightness. For Canon cameras, Simon recommends setting it down to two. If your LCD screen is too bright, you'll think you've got a great exposure when it's really too dark.
2. Set your White Balance to MANUAL and set it to 3800 Kelvin. It's not always necessary, but if you shoot multiple photos that you want to join together later, it's a lot easier when they all have the same white balance.
3. Set your photo quality to RAW, for better dynamic range.
4. Set the camera mode to MANUAL.
5. Use your lens's widest aperture, to let as much light in as possible.
6. For Full-Frame cameras, set your ISO from 3200-6400. For smaller sensors, between 1600-3200 should work. It also depends on your location, and the level of light pollution.
7. If your camera offers a "Level" setting, use it. It works like a carpenter's level, to tell you if your camera is square with the horizon line (it can be hard to tell in the dark).
8. Set a good shutter speed. What does that mean? It depends on your camera.
For a full-frame camera, use this equation: 500/focal length (mm) = maximum exposure (in seconds)
EXAMPLE: If I have a 20mm lens, 500/20=25 seconds I can hold a shot before I notice star streaking.
For a smaller sensor (what we use at school), use this equation: 300/focal length (mm) = max. exposure (in seconds)
If you set your shutter speed beyond these maximum times, you will notice your stars are streaking. This is because the sky is moving! Actually, no, to be precise, it's because the Earth is spinning. As the Earth rotates, our view of the sky changes. If you want to capture star trails, then fine, you're not breaking any rules. It's just a creative choice you need to be aware of.
Star Trails
One way to photograph star trails is to choose a really long shutter speed, say an hour or longer. There is a risk, however, as any big flash of light will ruin your photo. Alyn Wallace recommends taking multiple 20 second photos at intervals, and stacking them together in Lightroom. That way, you get the option to make a time-lapse video and a star trail photo with the same pictures.
Make sure your camera saves the individual photos while in "intervalometer" mode, because some cameras do, and some don't. If not, you can set your camera to Bulb mode, and then use your intervalometer to set the intervals manually. Set the length of each photo to about 20 seconds. For the interval, if you have a good camera battery, set to 1 second. Or, if your battery is weaker, you can set it to 2-3 seconds to be safe. Turn off LONG EXPOSURE NOISE REDUCTION. In your intervalometer, set N1 to 999 - this is the number of photos it's supposed to take. Alyn sets it to the maximum so it keeps going until he stops it manually.
So far as composition, in the northern hemisphere, all the stars go in a circle around Polaris, the North Star. It alone sits still, while the other stars dance around it. Depending on where you aim your camera, you may get concentric circles, or arcs the face up or down.
Focusing Your Camera
For night sky photography, focusing your lens is the main challenge, and you don't want to use AUTO FOCUS. It'll waste lots of time trying to find something to focus on, and in low light, it just can't find anything.
Method 1 (DSLR Cameras)
Some lenses have an "Infinity Marker" for focusing on things very far away. But, it's usually not perfectly accurate. So, to set your lens for the evening, you first need to focus on something very far away during the day - say the sky, perhaps a cloud way off in the distance, so it's easier to focus on it. Once you have that in focus, turn your lens to Manual Mode, and then don't touch it again. You should also place a little marker on your lens to show where that focus point is, in case you accidentally change it (Simon uses a little Post-It Note and tapes it on the lens).
Method 2 (Mirrorless Cameras)
An alternative method (also using Manual Focus) that requires a Mirrorless Camera, is to find the brightest star you can, and magnify the LCD screen on it, as much as possible. Then focus the lens manually, until that star is crisp and sharp. You'll know it's right when the star is smallest.
Post Processing
So, even with the best equipment (Simon uses a Canon R5 ($3,400) and a Sigma 20mm, F1.4 lens ($800), you're still going to wrestle with the high dynamic range from the shadowy ground and relatively bright sky.
In Lightroom, you can:
1. Raise the exposure.
2. Raise the shadows.
3. Create a mask for the sky. Lower the exposure, raise the contrast, raise the clarity a bit. Lower the color temperature a bit, if you want the sky bluer. Use dehaze a bit to cut down on light pollution.
4. Add a radial gradient mask for the Milky Way. Set it at a diagonal, to match the tilt of the Milky Way core. Increase the exposure and contrast, raise the whites a bit, lower the shadows and blacks. You want to help the Milky Way pop out a bit, but don't over-do it or it'll look unnatural.
5. Make a linear gradient mask at the top of the photo to make the top of the sky a bit darker - like during the day. Use contrast to do this, not exposure, or the stars will also darken.
6. Add another linear gradient at the bottom to darken it a little bit.
7. If your subject (car or building, etc.) looks flat, you can add a radial gradient centered on it, to raise the exposure and shadows. You can play with the colors as well.
8. You may want to add a bit of overall vibrance to the image.
9. You may add a gentle vignette as well.
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