Where and When to Shoot
To use Starry Landscape Stacker, you must first take some pictures. I like subjects with large obvious shapes in the ground. Unless you plan to illuminate the foreground, there will not be lots of detail visible in the ground so don’t rely on the detail to make the picture work. I try to plan to shoot on nights with at least some moonlight on the foreground. Clouds are a problem because they typically move quite quickly. There is no good way to deal with them—they will be blurred in the final result. Airplanes are not an issue because the algorithm Starry Landscape Stacker uses to combine the images will eliminate the airplanes. Meteors, satellites and any other bright objects moving quickly through the image will also be removed. Sometimes (if you are lucky) even cars and photographers walking through your shot holding a flashlight will be removed.
In summary, you want:
strong shapes in the foreground
some illumination for the foreground
clear sky—minimal clouds, airplanes, smoke or dust
minimal light pollution (although I have seen nice images where the glow of a distant city is part of the composition)
Equipment
The obvious tools you will need are a digital camera with a cable release, a sturdy tripod to hold the camera, and a good lens. These images will expose all the flaws in your lenses for two reasons. First, it is necessary to shoot at maximum aperture, which is usually when a lens is at its worst. Second, the sky is a mix of small bright stars and a very dark background. This high contrast will expose flaws in your lenses that you never knew existed.
You should take some test exposures with your lenses to see how they perform. Consider borrowing or renting some lenses to try to get a broad picture of how different lenses perform. The best time to make these tests is on cool dark nights with no moon. The goal is to render small bright stars to a single pixel. The best lenses can do this. Many lenses cannot, so try your lenses out in advance.
One other important piece of equipment is a dim red flashlight. This light is to help you to read your notes on exposure times and other camera settings. You have to be able to do this while preserving your night vision which you will need to compose and focus. A red light will not compromise your night vision as much as a white light. When shooting with others be aware of when their shutters are open when using your flash light no matter how dim it is. It is amazing how little light it takes to ruin an exposure. If you want to use a light always ask first.
Exposure Control
When we choose exposure settings, we are typically dealing with three variables: aperture, exposure duration and sensitivity or ISO setting. We want to keep the ISO setting low to reduce noise, we want the exposure duration to be short enough to freeze the motion of the subject (unless we intend to have motion blur), and we choose an aperture that gives us the required depth of field. Sometimes it is difficult find settings that meet all of our goals. Shooting starry landscapes is one of those cases.
Since depth of focus is not an important issue for the stars and we are working with little light, we will choose the largest aperture (smallest f/ number) at which the lens is sharp, even in the corners. (Advanced technique: If you need the foreground in focus, shoot some foreground exposures at different focus settings with a low ISO and a long exposure. Then focus stack and blend the result with the stacked sky image).
Exposure duration is determined by the focal length of the lens. Imagine you are taking a picture where you are aiming straight out from the equator. This is the worst case and will require the shortest exposure time. In 24 hours the stars will appear to move all away around the earth and back to where they are. If you just glance at the sky, you may think they are hardly moving. But watch for a few minutes and you will appreciate how fast they are moving. We can do the math and determine that with a 16mm lens on a camera with a 35mm full-frame sensor and 12.8 mega pixels, a star will move from one pixel on the sensor to the next, in around 5 seconds. So 5 seconds is a good starting point for an exposure time for this lens and camera which I used in 2007. With longer lenses or sensors with more pixels (like modern mirrorless cameras), the exposure times may have to be shorter.
When aiming more towards the north or the south the exposure times can be longer--for example, Polaris (aka, the north star) does not appear to move at all. You could do the math for your camera and lenses, but in practice, it is best to make many test exposures. The goal is to find the longest exposure time you can use at each focal length, and still have the stars appear to be points. In practice, the exposure time that works best is likely to be longer than the time you would calculate.
Summarizing so far: aperture is set to largest opening (lowest f/ number) at which the lens is sharp and the exposure duration is determined by focal length but is as long as you can tolerate without the stars leaving a trail that is too long. This leaves only ISO setting to control the exposure. The best way to determine the ISO setting to use is to take lots of test pictures and look at the results.
I have found that to get the results I want with a Canon 5DIV and 5Ds, I increased the exposure duration to 15 seconds. I used f/4, 15 sec, ISO 3200 with these cameras. This is with an 11mm lens. This setting works remarkably well with any dark sky. This is because the stars are always the same brightness no matter where and when you are, it is only the light in the air that is changing. With a Canon R5 camera I have been experimently with shorter exposures and lower ISO. I now always use ISO 1600 and exposures as short as 4 sec.
The images I capture initially appear very dark. Stacking and then post processing can brighten the images considerably still keeping the noise very low. And, because of the low initial exposure, only the brightest stars are blown out, leaving much more color in the stars.
Lighting and Atmospherics
Your planning obviously includes selecting a subject. But it must include some thought about how the subject will be lit. While moonless nights produce the clearest and darkest skies allowing the most stars to be seen, I think the best pictures often include a small amount of moon light on the landscape. The amount of light coming from the moon will affect your choice of subject and how you compose. If you know when and where the moon will rise and set and how bright it will be, you can plan your shots and be in position when the light is the way you want it to be. Another alternative for lighting the foreground (which may include mountains many kilometers away from your position) is to shoot a foreground shot at twilight. I have seen this produce results with a natural appearance.
It is also important to think about clouds and smoke. It is best to avoid clouds because they usually move too quickly. If clouds are seasonal, you should plan to shoot during the season with the least clouds. Also note that in many wilderness areas, wild fires and controlled burns are seasonal. The smoke they produce can be a major problem for photographing stars.
Ideally, you want to plan to take your pictures when clouds and smoke are unlikely, and the moon will be in the correct phase and at the right time to illuminate your scene in the dark of night. In practice this degree of coordination may be impractical, but it is useful to know what to expect, so you can make the best use of what nature gives you. Many websites and photo planning apps for smart phones can supply moon rise and set times as well as moon phase.
Capturing Your Images
Capturing the images is often a lonely and cold job so dress accordingly. You will need more clothes than you think. Gloves, hats, long underwear, down parka, I have worn them all, in the summer, in sunny California. If you are in rough terrain consider working with a buddy.
Ensure that your camera is set to capture images in RAW mode, not JPEG. Long-exposure noise reduction should be turned off. Long-exposure noise reduction doubles the time it takes to capture the images which reduces the quality of the alignment, and using dark frames (discussed below) with Starry Landscape Stacker will produce a better result than the in-camera long-exposure noise reduction. I suggest you set these options on your camera at home where it is warm, comfortable and well-lit.
When you get to your location, let your eyes dark-adapt for a good long time so that you can compose and focus. It is difficult to compose and focus on a truly dark night and you will need your night vision.
Begin by turning off autofocus and then focussing on the brightest object in the sky, trying to reduce it to the smallest point that you can. With a dSLR it is possible to get close to correct focus looking through the viewfinder, but I find that live view mode is essential to get the focus exact. I start by finding a bright star and focus as best I can in live view by trying to make the image of the star small. Then progressively zoom the live view refocusing at each step. Before I got a mirrorless camera with a good EVF I used a loupe while doing this to get a better view of the display on the back of my camera (e.g., a Hoodman HoodLoupe®). Cameras with EVFs have a strong advantage here. But the key will be zooming in on a bright star and adjusting the focus to make it as small and sharp as possible. I have experimented with a Focus On Stars tool (https://focusonstars.com/). It does not work with all of my lenses, but for those that it works with it allows me to focus faster and more accurately. I carry it with me and use it whenever I can.
Like focusing, composing is made difficult by the dark. I often have darker features at the edges of the frame making it impossible to know exactly what is in the frame. This is frustrating but practice, experience, scouting locations during the day and a few test exposures help.
After you have set your exposure based on your experience, and focused and composed, you want to collect your images quickly and with minimal camera shake. It is important to collect the images quickly because the alignment will be better if the stars have moved less during the collection of the images. The best way to collect the images is to set the camera to burst mode, go into live view (if you are using a dSLR) and use your cable release to lock the shutter button until you have all the images you need. I typically collect images for at least 5 minutes. (My current thinking is that longer--more images--is better, but there is a limit. When I think I have something really special I collect light frames for 10 minutes). By shooting in live view, the mirror will be locked up, leaving only the shutter as a source of camera shake. Using burst mode and holding the shutter button minimizes the time between images. It is important to have autofocus turned off before entering into live view, because by default Canon cameras (and maybe others) will continuously autofocus in live view, and since they cannot focus on stars at night, this will mess up the focus you so carefully set. (You can turn off the automatic autofocus in live view but that still leaves open the possibility of accidentally bumping the focus button--something I have done many times on dark, cold and windy nights).
Capturing Dark Frames
With Starry Landscape Stacker Version 1.9 and later, you should consider capturing some dark frames. Dark frames can be used to reduce fixed-pattern noise, that is, noise that tends to be consistent from frame to frame such as hot pixels and glow around the edges of the sensor. To capture dark frames, put the lens cap on and shoot 10 frames with the settings you just used. Do this just before or just after you capture your light frames. Some cameras with really low-noise sensors might be able to save time by only capturing 5 dark frames. If your camera has a particularly noisy sensor, you might want more than 10 dark frames. If your lens cap does not fit tightly, you might have to cover your camera with a dark cloth. It is important to block all light from reaching the sensor.
With versions of Starry Landscape Stacker before Version 1.9 I recommend that most users not use dark frames.
Preparing Images for Starry Landscape Stacker
Starry Landscape Stacker accepts images in many RAW formats as well as TIFF files. Some reasons on why you might prefer one over the other, and instructions for converting the RAW format images to TIFF are here Preparing Images for Starry Landscape Stacker.
Last updated December 2023.