How is this possible?
When you think of photographing the Milky Way, you usually think of doing it from a dark location away from light pollution. What if I told you it was possible to photograph the Milky Way from your back yard?! There’s no substitute for a truly dark sky, but it’s still possible to do through light pollution.
It’s possible to capture the Milky Way through light pollution by using a technique call Exposure To The Right, or ETTR. With this method, you intentionally overexposure your image as much as possible without blowing out the highlights. ETTR allows the camera to capture a better signal to noise ratio – the signal being light, or in this case, the Milky Way.
The Downside to ETTR with the Milky Way
With all good things, there must be a catch. So, what is it? In a proper Milky Way exposure, you might notice that some of the brighter stars have clipped; meaning they’re overexposed. When a star is overexposed, it won’t have the color detail of a non-overexposed star. What happens if you take that same exposure and increase it, or expose to the right? You’re going to overexpose more stars. What about the highlight alerts on my camera? The main hump on your histogram will be from light pollution and night sky. Being that stars are faint but brighter than the light pollution, they won’t always register as being clipped on the back of your camera.
I learned about this method from a Lonely Speck youtube video created by Ian Norman. If you’re not familiar with Ian, he’s the creator of Lonely Speck. He’s also a photographer, engineer, and entrepreneur with a passion for photography and teaching. Check out the Lonely Speck website here. Watch the Lonely Speck video here!
Isn’t ETTR for Portraits?
When I first started in photography, I did a lot of portrait work. Exposing to the right is an excellent technique for portraits. Typically, bright and vibrant faces make for better images than dark and shadowy ones. Unless of course, you’re going for a moody look. I would always meter for the face, and then slightly overexpose it. Can the same technique work for the Milky Way though?
Proper Milky Way Exposure
A proper Milky Way histogram will have most of the detail on the left half of the histogram. The data will be just off the left side so that you’re not clipping your blacks. The spike of the Milky Way will peak over the midpoint of the histogram. If you’re not sure how to properly expose a Milky Way image, check out this free Photog Adventures webinar!
The ETTR Histogram
With this method, the histogram will be pushed to the right, but not so far that you clip the highlights of the sky. Remember, you’re going to clip stars with this method. You can see in the example below that the ETTR histogram is drastically different from the properly exposed histogram. Your image, at this point, will appear to be completely washed out.
Post Processing ETTR Milky Way Exposures
With an ETTR Milky Way image, you won’t be able to do your typical workflow. From a high-level overview, you’ll want to start by decreasing your exposure. Doing this will make your histogram look like that of a properly exposed histogram. From here, white balance your image like you normally would. Then add the secret recipe. Contrast, contrast and a lot more contrast! Oh, and some vignette removal. All that contract will over exaggerate the vignetting.
Check out my before and after example:
In this example, my before image looks thoroughly washed out. The streetlight in front of my house appears to be a mini sun in the bottom left. It was so bright that I clipped the highlights in that area.
Learn more about light pollution
Light pollution is slowing turning night into day. If we don’t do anything about it, we will get to a point where we can no longer view the stars at night. To learn more, check out this article by Kirk Keyes on how to save our night skies. In this article, Kirk talks about different types of light pollution and what you can do to help. Every little change makes a difference. One of my favorite Dr. Seuss quotes, “Unless someone like you cares a whole awful lot, nothing is going to get better. It’s not.”
Try it for Yourself!
I was skeptical at first but pleasantly surprised that I was able to capture the Milky Way in light pollution. It’s amazing how much information is in a single RAW file. If you happen to find yourself in an area of heavy light pollution, I encourage you to try this for yourself. Let me know if you’ve tried this, or if you plan to. If you have, upload your results and let us know about it!