June Newsletter - Shooting the Milky Way
Jun 15, 2020
One of the new areas I want to get into is astrophotography. It’s still all about the light, but then there isn’t much and it takes quite a different skill set. Two prime objectives. First, the Milky Way. You can get this photo from any latitude, so should be just a matter of practice. The second is the northern lights, but I’ll save that for another time.
Obviously, we can’t photograph the whole galaxy since we live inside of it. That famous white streak that dominates so much of the night sky is actually the light of billions of stars whose light, from our point of view on earth, seems to blend together, sporadically obscured by dust and gas clouds. In reality, all we are seeing is a small, edge-on view of the galaxy’s plane. Small, but impressive.
Here's some steps to follow:
1. Find A Dark Sky Just waiting until nighttime won’t do. A dark sky free of light pollution is the first and most important requirement to even seeing the Milky Way, let alone photograph it. The moon can have an impact on your Milky Way photos; shooting during a full moon will wash out your images. Try to shoot during a new moon. It goes without saying that you need a clear sky for this to work.
2. Know When And Where To Look
The part of the Milky Way that is most easily visible to the naked eye isn’t visible all year round, especially for those in the Northern Hemisphere. The optimal times are February through September. You will find your celestial subject in the southern half of the sky, rising from the east.
3. Use A Digital Camera With Good High ISO Capabilities
You’ll be shooting at night with very little available light; you want your camera’s sensor to be able to handle the shooting conditions without introducing an excessive amount of noise. If you have night time noise reduction on your camera, this is the time to use it. Just remember that exposures will take twice as long, as the camera is taking two photos. One with the lens closed so that it can subtract out the noise of the exposed photo.
4. Use A Fast Wide Angle Lens
This is simple, open your aperture as far
was it will go. The same principle applies
to focal length; go as wide as you can. You may be seeing only a fraction of
the Milky Way, but it’s still monstrous in size. The wider your lens, the more
of it you can capture.
5. Use A Tripod
This really isn’t optional. Bells and whistles are nice, but sturdiness is your number one concern.
6. Use Live View
To avoid the headache of trying to focus in the dark, use your camera’s live view feature to manually focus on a bright star.
7. Start With ISO 3200
Referring back to the first point, a high ISO is essential to collecting enough light to render a bright image of the Milky Way. Under typical conditions, ISO 3200 is a good starting place. Remember, while high ISO settings will be more light sensitive and reduce exposure time, it also introduces more noise. Everything is a trade off.
8. Set A Long Shutter Speed
This is how you will capture more light and create a sufficiently bright exposure. There just one problem, though. The planet doesn’t care if you’re new at astrophotography; it’s going to keep on rotating, which means if you leave the shutter open for too long, you’ll end up with star trails. There’s nothing wrong with star trails when that’s what you’re aiming for, but they aren’t really desirable for photographing the Milky Way.
To get pinpoint stars, use the “500 rule”, which calls for you to divide 500 by the focal length of the lens you’re using. So, if you have a 24mm lens on a full-frame camera, you will set your shutter speed to 20 sec. (500/24 = 20.83).
If you’re working with a crop sensor camera be sure to account for the crop factor (typically 1.5 for Nikon and Sony, 1.6 for Canon). As an example, using the same 24mm lens on a Nikon crop, you’d end up with an effective focal length of 36mm (24×1.5 = 36). Applying the 500 rule will yield a shutter speed of 13 sec. (500/36 = 13.89).
9. Set A Wide Open Aperture
Remember, it’s all about collecting as much light as possible; depth of field isn’t the primary concern here
10. Compose Your Shot
There’s no right way or wrong way to compose your shot, but you can create a sense of depth by framing this as a standard landscape shot with the Milky Way serving as the background. Just because it’s dark out doesn’t mean you should forget about the foreground. You can add interest to your scene by including hills or mountains, trees, rock formations, or even a person.
11. Get A Satisfactory Exposure
It’s very likely that your first shot won’t be an exposure you’re satisfied. If there are star trails, decrease the shutter speed. When you notice there’s too much noise, simply decrease the ISO. Finally, when you spot the shot is overexposed, check your surroundings for light pollution; decrease shutter speed; stop down the lens; or decrease ISO. If it’s underexposed, make sure you’re using the widest aperture on your lens; increase shutter speed (but beware of star trails forming); increase ISO.
12. Process It
There will be a lot of variation at this final stage and, again,
there is no one right way to handle the post-processing of your shots. The two
most important things you can do to make post-processing a little easier is to
shoot raw and get the best exposure you can in-camera.
You may need to apply some sharpness and noise reduction. According
to some sources, the color temperature of the Milky Way is around 4840°K; if
you find it too much on the yellow/orange side, adjust white balance until you
have a neutral scene.
You will definitely need to increase contrast; it’s okay to be a
bit heavy-handed here, so long as you’re not losing shadow detail.
Other settings that you need to take care of are:
Have the camera on manual mode on a sturdy tripod.
Turn off image stabilization.
Have a wide angle lens between 14mm to 24mm to get a good view of the Milky Way in the frame along with foreground.
Set the aperture to the widest. Start with the lowest ISO possible, about 1600. Depending on the result, you can decrease further or increase the ISO up to 3200, above which the image quality can start to deteriorate.
Put your lens on manual focus and focus on the brightest star in the sky. Zoom in on live view and turn the focus ring till the star shows up as a bright point in the screen.
Calculate shutter speed based on one of the rules above.
Use the mirror lockup feature if using a DSLR to avoid blur due to camera movement.
If you try this, good luck and I would like to see your efforts.
Photo credits in order of appearance: Jason Henkins on Flickr, John Lemieux on Flickr, Damian Witkowski on Flickr