The Milky Way Shooting

Photographers spend a lot of time, energy, and money to capture what they see. That’s why a lot of shooters object to AI. It has nothing to do with what we see with our eyes.

For many decades, even the distortion caused by wide angle lenses was eschewed. I remember in the early 70’s debating beween buying a 24mm lens and a 28mm (this pre-dated good zoom lenses). The camera salesman in the biggest photography equipment store in Los Angeles advised me to get the 28mm because, he said, there was less distortion. I ended up getting the 24mm specifically because of the distortion.

When it comes to night photography, we have come to accept that we don’t really capture what we see. Because of the camera’s ability to accumulate light, we can make a scene that is quite dim to our eyes look like broad daylight with a long exposure. Our ability to manipulate light like this is remarkable.

When it comes to photographing the Milky Way, all of the pictures you see in print and online, and in this article, have been enhanced due to manipulation of the exposure by using a long shutter speed in combination with a relatively high ISO. The reason for this is simple.

As we view the Milky Way through miles of atmosphere, the light of billions of stars that make up our spiral galaxy is diminished. On a clear night when you are far from city lights, and once your eyes have adjusted to the darkness, you can see the Milky Way clearly, but it’s not bright. Photographic artistry requires more exposure, more contrast, and even more color saturation. It’s not that you are manipu- lating nature per se; in fact, you’re just creating an image that probably is indicative of what you’d see from another planet without atmosphere. Enhanced pictures of the Milky Way actually show the reality of the cosmos.

Ideal gear

If you are new to photographing the Milky Way, there are really only two things you’ll need and I’m sure you have both: a sturdy tripod and a wide angle lens. You also need a camera that permits a long shutter speed.

Regarding the wide angle lens, for Milky Way photography it’s best to use the widest lens in your arsenal. The picture at right was taken in New Zealand with a 14mm lens. Many photographers use a 16mm focal length, and if you don’t have anything wider than, say, a 24mm lens, then that’s fine, too.

Equally important is the maximum lens aperture. The larger the aperture, the lower the ISO will be and the less time the shutter is open. If you are in the market for an extreme wide angle especially for shooting in dark environments, I recommend the Sigma f/1.8 14mm lens. It is heavy because the front glass element has to be so large, but it’s worth the weight in sharpness, angle of coverage, and especially because of it’s unusually large lens aperture.

Shutter choice

The length of time you expose for the Milky Way is significant not only in the camer’s ability to accumulate light, thus rendering the relatively dim sky quite bright, but due to the rotation of the Earth the stars appear to move across the sky. Assuming you don’t want to capture star trails, the exposure time has to be limited. 30 seconds is an absolute maximum, particularly if you’re using a 16mm or 14mm focal length.

Wide angle lenses don’t magnify elements in photographs like telephotos do, and therefore movement is less apparent. If you are going to use a 24mm lens to photograph the Milky Way, I would not use a shutter speed more than 20 seconds. Beyond that time, the stars start to appear as oblong shapes in the process of forming star trails. The ideal is to insure that each star is a point of light.

I prefer to keep the exposure to 15 seconds to avoid even a hint of movement in the sky.

ISO and noise

As you decrease the exposure time, say from 30 seconds to 15 seconds, the ISO must raised to maintain a good exposure such that the night sky appears bright and dramatic. When you change the shutter time from 30 to 15 sec- onds, that is a one f/stop decrease in light. That means to compensate and maintain the correct exposure (based on exposure testing you’ve done), the ISO has to be doubled. That, in turn, means an increase in noise. And noise is most pronounced in dark portions of a photograph and particularly in night photography.

I use Topaz DeNoise for most of my night sky images. It does an excellent job, but it has limits. Once you start shooting above 4000 ISO at night with many cameras, producing a sharp, high quality image becomes problematic.

Because I shoot with an f/1.8 aperture, I am able to use ISO settings in the 1250 to 1600mm range. Depth of field is irrelevant if you are only shooting the sky. If you include something in the foreground that’s close to the camera, then depth of field becomes important to consider.