I still remember the first time I really saw the Milky Way for the first time. I was on a backpacking trip and after spending the day swimming and photographing the beautiful Minarets Lake nestled deep in the High Sierras, the reflection of the Milky Way caught my eye. Just like that, I was drawn to the edge of the lake shore in utter awe of how bright the ‘arms’ of our galaxy appeared both in the sky and on the lake’s surface. Since then, I have pursued the feeling I felt that night. The feeling of viewing something bigger – much bigger – than humanity itself is something astronomers have chased for centuries. Unfortunately, the Milky Way isn’t visible to 80% of Americans and a third of the world’s population, so the excitement felt when viewing the Milky Way on a clear, dark night is somewhat of an anomaly for city dwellers. Fortunately, with the advancement in digital sensors over the past decade, nightscape photography is becoming easier to capture the amazement of the Milky Way and share it with a large digital audience.
Nightscape photography is effective because it combines the scientific fascination of the night sky with the natural wonder of our known world. It’s the only style of photography that can question humanity’s relationship with our planet and the celestial universe. As more and more Americans are cut off from seeing the Milky Way in their daily lives, this style of photography is becoming more important, as it offers a glimmer of escape from our busy cosmopolitan lives. Although, yes, landscape photography can stimulate these same emotions, nightscape photography inspires a wanderlust to lay under a dark, clear sky and gaze into the Milky Way for hours.
The basics of nightscape photography are pretty simple and have become almost formulaic in recent years; setup a DSLR on a tripod, set the shutter speed to 15 seconds at 6400 ISO and open up the aperture as large as it will go. I’m going to assume you know this much already, so in this article, I’m going to discuss some lesser-known tricks to help you set your nightscape images apart from the competition, including planning your excursion, choosing the right equipment, as well as some in-camera settings.
Plan Your Trip
Before we head out to some dark skies to photograph, we need to determine when the Milky Way will be visible, if the moon will be obstructing it, and when we can expect clear skies. The Milky Way is only visible between February and October, with the galaxy revealing itself in the early morning during spring and in the evening by fall. To figure out the exact time it’s visible, download a smartphone app such as the SkySafari, or a desktop program such as Stellarium.
These programs are also useful for determining moon phases and positioning. Moon cycles last between 4 and 5 weeks, with new moon being the best time to photograph because the light side faces away from us. When the moon is brighter than first quarter, the light reflected off the moon overpowers the Milky Way, making nightscape photography impossible. Use Google to figure out the current moon phase, and what days new moon is expected. This will usually create a window of a few days when viewing conditions are perfect for photography.
Now, we hope for the weather to cooperate. Although weather apps are great for determining forecast, they offer limited insight on cloud cover and visibility. Using a clear sky chart like the one from www.cleardarksky.com helps us figure out what seeing conditions will be expected, broken down by the hour. Squares with a dark blue or black color represent the best visibility, while light blue and white represent hours when the sun is up.
As landscape photographers, we almost instinctively use a wide angle lens when shooting, but this isn’t always the best option for Milky Way images. While we can photograph subjects like sunsets or the ocean and produce a million different variations, the Milky Way does not change (that is, in our lifetime). For this reason, lens selection is one of the most important decisions for a nightscape photographer because it can drastically alter the composition of your image. As nightscape images have risen in popularity on photography platforms like Flickr and Instagram over the past few years, they have become formulaic. Fortunately, using the right lens can break up the monotony, especially when using a 50mm lens to piece together a mosaic of the night sky. 50mm lenses also produce minimal distortion, making them an ideal lens for piecing together a panoramic or mosaic of the night sky.
We also might want to consider a few things before opening the lens to f/2.8. Lenses are more prone to chromatic aberration and in some cases vignetting when set to their widest aperture, especially if it’s f/2.8, f/1.8 or f/1.4. For example, the cropped image above was shot with a Canon 5Dsr and Zeiss 50mm prime shot at f/1.4. The original image was cropped, however, it shows some clear chromatic aberrations around the inside of the brighter stars in the image. To prevent this from happening, use a wide aperture, but not the widest. Instead of using f/1.4 or f/2.8, try setting your lens to f/3.5. This will reduce the effect of chromatic aberration in the bright stars in your image.
Nightscape photography also poses an interesting dilemma: how do you contend with the Earth’s rotation? Any exposure longer than 15 seconds will develop star trails, so in order for us to capture a bright & detailed Milky Way, we need to find a way to ‘track’ the stars as they move through our frame. Last year, optics & telescope manufacturer Sky-Watcher released a solution for this. The modular Star Adventurer attaches to any photographic tripod and enables long exposures of the Milky Way without the need for an expensive computerized telescope setup. Rather than restricting images to 15 second exposures, the Star Adventurer allows you to shoot exposures anywhere from 30 seconds to 20 minutes, without creating star trails.
Take the next image for example. This 20-panel mosaic was captured at 2 minutes at 1600 ISO at f/3.2. The detail and color captured here would not be visible with a 20 second exposure, so using a tracking platform can unlock new opportunities for your photography and set you apart from other nightscape photographers limiting themselves to grainy 15 second exposures.
Of course, shooting stationary terrestrial objects as your camera is mounted to a moving platform makes long exposures nearly impossible. For this reason, piecing together a mosaic like the next image, or shooting the Milky Way separately and using Photoshop to composite the two images together will give you better results, because you can expose for your foreground and background separately. Far too often I see beginning astrophotographers overexpose their foreground while underexposing their background, leaving out vital nebulosity in the Milky Way.
Shooting a successful nightscape takes more than shooting a 15 second exposure at ISO 6400, so let’s discuss some in-camera techniques you can use to improve your images. Using a tracking platform such as the Star Adventurer not only lets you shoot longer exposures, but also helps reduce noise by allowing you to shoot at a lower ISO. Shooting 30 seconds at ISO 6400 is comparable to shooting 4 minutes at 800. However, the difference in noise between ISO 6400 and 800 should speak for itself.
While shooting, you should also consider giving your sensor a ‘cool-down’ time anywhere between 1 and 5 minutes after each exposure. The longer the sensor is active, the more heat builds up, which raises the noise level exponentially. On a cold, dry night, the sensor might not heat up as quickly as it would on a humid summer evening, but regardless, allow a few minutes between each exposure to bring down the level of noise in the sensor.
White balance is almost always best adjusted in post-production. However, it doesn’t hurt to get it as dialled in as possible before we start shooting. Some photographers choose to leave it set to AWB (Automatic), while others prefer Tungsten, which creates a deep blue tone across the sky. While everyone has their own preference, I recommend setting the camera to the custom white balance setting before choosing 3,800k in the camera menu. This will give your images a pleasing celestial blue tone without losing some of the deep-red tones present in most celestial bodies.
Some DSLRs also have built in ‘Long-Exposure Noise Reduction’, which is perfect for those who dislike spending much time in Photoshop with their images. Early cameras would fire a dark frame after each long exposure, and subtract the noise in it from the intended photo. The process was lengthy, so manufacturers worked some basic noise reduction into the image processing. Noise reduction does have a reputation for softening details in your mid-tones, and is especially apparent when the file is zoomed in 100% or printed. To help confront this issue, newer Canon models have 3 levels of noise reduction: low, standard and high. My advice? Play around with them if you don’t intend to crop or print these images, but if you enjoy post-processing, I’d recommend sticking to Photoshop for noise reduction.