You may have seen a photograph like the one above and wondered how the photographer captured the Milky Way AND include a properly exposed, detailed landscape. The easiest answer you might hear is “photoshop”, and while there may be truth to that, it doesn’t paint the whole picture. When taking photographs of our night sky, it is important to understand the different methods and different kinds of light one may use to illuminate their scene. In total, there are five methods for exposing for landscapes with astrophotography: No light (silhouettes), light painting, starlight, blue hour and a partially lit moon. In this article, I will cover each method as well as their pros and cons.

No Light

Before we begin, let’s look at astrophotography with the absence of light. Unless you shoot at an absurdly high ISO, (25,600+) foregrounds or landscapes photographed at night will be dark or completely black. This isn’t necessarily a bad thing though, silhouettes, particularly of trees or arches, can make for beautiful photos. Silhouette night shots are also much easier to photograph and process. Occasionally I have come across a beautifully shaped subject without an interesting foreground. In these instances, shifting focus to the silhouette makes for a more interesting photograph.

Pros: Easy to do. No photoshop required.
Cons: A limited number of subjects look good silhouetted.

Light Painting / Low Level Lighting

This is probably most peoples introduction into illuminating the landscape in night photography. The goal of light painting is is simple, try to match the exposure of the foreground with that of the sky. While you can do light painting with a headlamp, the results are almost always less than stellar. Instead, the best technique for light painting involves setting up one or two low-powered LED light panels, strategically placed around the scene. This way, you can dial in the brightness and placement of the panels to get great results. This specific type of light painting is called Low Level Lighting. The downside of light painting is that it doesn’t work for large vistas such as mountains or places like the Grand Canyon. Light painting is best used with simple subjects and things that don’t move.

When I know I will be using Low Level Lighting, I will being several extra tripods with me to help set up the lights. My preferred brand of LED light panels is Lume Cube.

Pros: Relatively easy to setup. No masking required. Good results.
Cons: Requires additional equipment. Doesn’t work with large scenes or vistas.

Starlight Blend

Like the name suggests, this technique uses the natural light of the stars to illuminate your foreground. Because starlight is extremely faint, you need to expose for a much longer period of time to see the landscape, usually in the range of 5-10 minutes, even at f/2.8. With this thought comes some challenges. The most obvious is that an exposure this long will result in significant star trails, necessitating the need to combine the starlight landscape with a separate image of just the night sky in photoshop. The second issue that arrises is the introduction of hot pixels. The longer your exposure time, the more your cameras sensor heats up, and when it gets too hot, hot pixels become visible. This can be negated by using your cameras built in Long Exposure Noise Reduction or using the Dust and Scratches filter in Photoshop.

Starlight Math

A quick way of calculating how long to expose for starlight is take take varying test shots at an ultra high ISO and a fast shutter speed. Once your histogram looks okay, divide the test shot ISO by the ISO you are comfortable shooting at. Take the resulting number and multiply it by your test shutter speed to get your starlight exposure time. For instance, let’s say my test shot with a correct exposure was taken at ISO 32,000 and a shutter speed of 10 seconds, and I want to shoot at an ISO no higher than 800. I simply divide 32,000 by 800 which gives us 40. I then multiply 40 by our test shot shutter speed of 10 seconds, to give me an exposure time of 400 seconds.

Pros: Very natural look. Easy to process.
Cons: Flat landscapes. Longer time in the field.

Blue Hour Blend

This method combines photos of a landscape shot during blue hour with a photo of the night sky. The result is a believable looking image in which the landscape is visible. The term for this technique is called blue hour blending. The pros of using the blue hour blending method are that you can shoot many different compositions during the blur hour, and can even pull off things like focus stacking which would be difficult or impossible using starlight or light painting. The downside is that to acheive a believable blend, one must have a decent level of skill in photoshop. The process of matching colors and tonal values of the sky and landscape requires time and artistry. Another downside is the tedious process of creating a mask for the horizon when blending very complex images such as trees or jagged mountain peaks. Photoshop’s sky selection has come a long way, but it’s not perfect. Still, the unbelievable results are why almost all professional photographers have adopted the blue hour blending method.

Which Blue Hour?

Another important aspect of creating a blue hour blend is knowing which blue hour to use. Depending on the time of year and the direction the Milky Way is aligned, a morning blue hour might work better than an evening blue hour and vice versa. Let’s say it’s the end of the Milky Way season and the sun is setting just before the Milky Way rises to the west. Because you are photographing into the sun, your evening blue hour shot will have less definition and the horizon line will typically be over exposed. This makes the blend much more difficult than if you had shot the morning blue hour when the sun was casting light in the opposite direction.

Pros: Can be more creative with compositions. Dramatic results.
Cons: Significant Photoshop processing required. Not suitable for purists.

Moonlight

One last way to illuminate foregrounds for night sky photography is with the moon. This is a slightly more difficult method to plan, but is great for astrophotography purists. Unfortunately, some problems can come up. For instance, if the moon is too bright, it will wash out the night sky, or if the moon is in the wrong direction to your subject, it will be in shadow. The upside of moonlit astrophotography is that it can be done in a single shot and requires little processing. Moonlit astrophotography is best done during the waning or waxing crescent phases, when moonlight isn’t overly strong.

Pros: Extremely natural. No photoshop required.
Cons: Limited to which direction the moon is facing. Can create harsh shadows.

Final Thoughts & Ethics

While there are many different methods for lighting up your foregrounds for astrophotography, I find myself preferring blue hour blends. There is much more freedom to be creative with compositions, and I generally prefer the look of using a blue hour foreground capture. That being said, I generally don’t do fabricated composites. That is, each photo of the night sky has the Milky Way, stars or even aurora facing where it actually would be in the night sky. In almost every instance, I shoot the landscape and night sky portions of my photographs on the same night and match them to be as true to life as possible. Still, I am not the Milky Way police and don’t look down on what other people create through composites. Photography is an art form that doesn’t always represent reality.

Below are some of my favorite night sky photographs using the blue hour blending method.