Just over a year ago, I decided on a whim to try and capture photos of a meteor shower. The results were unimpressive, but I continued working at it in my spare time, and now I think I’ve arrived at a decent starting point for capturing good nightscapes and wide-angle astronomical images. Last weekend I finally got that meteor photo that started me on this journey. Along the way, a few interested friends have asked me for details about how I do it. Last year I posted some details about my first setup that produced decent beginner results. Along the way, I surveyed a huge number of blogs, discussion boards, books and other materials. It became clear to me that it is hard to find good, up-to-date references for beginners in this hobby (partly because the available equipment, software and techniques have evolved rapidly). This post is intended to provide a discussion of my opinions and experience from a beginner’s perspective. Here is a gallery of some of my images, followed by a discussion of equipment and techniques:
1. Online Resources
To start, I should acknowledge the value of many online resources. There are two different “flavors” of information online about night photography. The first “flavor” is astronomical imaging, usually accompanied by a desire to produce accurate, scientifically meaningful images. The second flavor is aesthetic night photography, which allows more liberties in composition and post-processing in order to create pleasing images. Both categories are useful and interesting, but the scientific techniques are sometimes overkill if the goal is to simply make a beautiful picture.
Here is a short list of resources I found most useful:
- Flikr — obviously this is where the beautiful photos live. Flikr is host to many excellent nightscape images, and most of them are well documented as far as how they were obtained. Several Flikr users have also posted useful tutorials, although nothing is quite comprehensive. Looking at Flikr image galleries is a good way to set goals for your own photography.
- Cloudy Nights — This is an astronomy discussion forum that often has great posts on astrophotography. Usually the emphasis is placed on telescope imaging, but not always. I’ve gleaned a lot of useful information from lurking on the cloudy nights forum.
- Catching the Light — An excellent collection of highly detailed tutorials on different types of astrophotography. This is an excellent reference but I’m going to try and streamline the recommendations in this post.
In addition, it is also helpful to read blogs written by other beginners, since they are likely discovering solutions to similar problems and can help point you to new ideas. I’ll link to Phil’s Astronomy Blog (just to select one from a hat). There are also dozens of mini-tutorials like this one, each one providing its own perspective, approach and example images.
2. Equipment and Practical Considerations
Obviously you’re going to need a quality DSLR camera, a sturdy tripod and a remote trigger for your camera. I’m also going to recommend a star-tracking device. What’s not obvious is the importance of organization and portability. You need to be able to transport your equipment to a dark location, assemble it efficiently, and keep track of your gear in the dark. For me, organization and equipment selection were truly the hardest parts of getting started. Here’s my setup:
When assembling your equipment, it is extremely important to avoid frustrating situations. Here are my recommendations:
- Camera selection: You need a proper DSLR camera that supports LiveView focus. I spent my first year working with an older Canon 350D, and found it was too difficult to achieve and maintain focus without LiveView. The situation was especially bad in winter. Also, a flip-out LCD screen is extremely helpful. If choosing a Canon model, get one that supports MagicLantern, you won’t regret it. A remote control is also recommended, and wireless is preferred. You can get all this new for around US$600, or used for much less. More expensive cameras do produce better quality images, but the low-end cameras still produce satisfying results. I chose to get the Canon 60Da and am very happy with that choice.
- Tracker: You don’t have to get a tracker right away. If you like projects, you might try building your own barn door tracker. I built one (actually I built three); it was fun for a while. Barn door trackers are impractical and violate my “least frustration” principle. They don’t transport well and require a lot of tinkering. For maximum happiness, the Polarie or iOptron SkyTracker are worthy purchases at US$300-$400. There is also a table-top equatorial mount for just US$70, but it is very limiting compared to the SkyTracker. The SkyTracker is also newly improved and very easy to use.
- Timer/Controller: In many instances it is helpful to let the camera run autonomously (timelapse sequences or image stacks, for example). Some cameras feature built-in intervalometers, so check for that. The MagicLantern firmware for Canon cameras provides an intervalometer function and automatic “bracketing” for high-dynamic range pictures (I’ll explain that later). These are very useful features that eliminate the need for any external timer.
- Lenses: Go wide-angle. Many of the best nightscape images include large foreground objects like buildings, trees, mountains, etc. It is popular to try and capture the Milky Way above a lake, for instance. For this style of image, very wide-angle lenses — even fisheyes — are commonly used. An alternative is to stitch together a panorama, which can also produce good results but is very time consuming.
- Bags and headlamps: Get a quality camera bag that will fit everything that you plan to use in the field. Organize it carefully; when working in the dark you need to do occasional inventories to make sure you haven’t dropped or forgotten something. Get a bright LED headlamp and cover the light with red cellophane tape, so that it doesn’t blind your night vision.
As equipment goes, I think this is the minimum list for having a good experience. Most people who are considering nightscapes will already have a camera and tripod. If not, or the camera doesn’t meet the right specifications, then some investment is required to get started.
3. Using the Camera in the Field
Finding a dark location is not as easy as it sounds. Fortunately, good results can often be achieved in suburban settings if the sky is sufficiently clear and the humidity is low. Many people have taken great images from their own yards or neighborhood sidewalks, and this is the best venue for rehearsing your technique. Always plan for at least two hours of shooting around midnight. Fumbling in the dark is a slow process, and 30-second exposures require a lot of patience. I usually bring podcasts to help pass the time. It is advisable to get a lot of practice before planning a trip to a remote dark site.
Here’s basic procedure:
- Setup the camera, tripod and tracker (if using one), and configure the camera in manual-mode, with manual focus. If tracking, turn off Image Stabilization if the lens supports it. Point the camera at the sky.
- Set the ISO to the maximum (usually 6400 in recent models). Open the aperture completely (set F-stop to minimum). Meter the scene and adjust the exposure normally. Then adjust the focus until you see stars appear on the LCD. Zoom in on a star and use it for fine focus. Note that the LCD may initially appear black, even after metering. This is because the lens needs to be very close to the correct focus before the stars are visible at all. If you are using a tracker, then you might consider a lower ISO to improve image quality.
- If using MagicLantern (which I recommend), use the intervalometer to take a succession of photos. Some will be better than others, and you can get an overall improvement by stacking the images in post-processing. You might also play with the HDR settings, which can help bring out faint detail by using a different kind of stacking procedure. (Note that tracking is recommended if you are planning to stack multiple exposures).
- Make some coffee and turn on a podcast. Or, if you are at home or at a camp site, you might prefer to drink something else. Or maybe you just prefer to look at the stars. It doesn’t matter because the process is quite automatic from here. If you’re out in the wilderness, try not to think about bears, since this is the time when you are most likely to worry about them.
4. Post Processing
Here’s where things can get really complicated. There are so many options for post processing, you can spend months adjusting the same image a thousand different ways. In this post, I’m mostly going to talk about open-source and/or free solutions for post processing. I’ll acknowledge that most people use Photoshop or Lightroom, but I prefer to use tools like the GIMP for general processing, Hugin for panoramas and image alignment, Luminance HDR for high-dynamic range processing and other independent software options.
Here are the basic options for post-processing:
- Stacking to reduce noise: One of the most common practices in nightscape imaging is to overlay and average together a number of exposures to achieve improved signal-to-noise ratio. If the images are well-aligned (i.e. because you used a tracking device), then this type of stacking can be performed manually in Photoshop or the GIMP. To automatically improve the image alignment, the “align_image_stack” tool (distributed with Hugin) can be used. The simplest procedure is:
- Open the first image.
- Open the second image on a new layer. Set the layer’s opacity to 1/2.
- Iteratively open each image as a new layer. For each nth image, set its opacity to 1/n (i.e. image 3 has opacity 1/3, image 4 has opacity 1/4, and so on).
- Merge all layers. The result looks pretty good after stacking 5 to 15 exposures.
- HDR stacking: An alternative stacking procedure is high-dynamic range (HDR) stacking. This is really popular on Flikr right now, and has produced some nice astronomical pictures. The basic idea is to take a series of frames at different exposure settings, called “brackets.” One bracket has good light balance, one is stepped a little brighter, one a little darker, and so on (the brackets can be automatically generated using MagicLantern). All the frames are added together (not averaged). The result cannot be directly displayed on the screen, so it is tone-mapped to produce a displayable image. The tone-mapping step can be done many different ways, and may help to reveal faint features or reduce the intensity of very bright features, resulting in a vibrant and detailed picture. I’ve been using Luminance HDR for this purpose, and got some results that I like (like this image of Andromeda with the Milky Way). HDR processing is really finicky though and requires a lot of time fiddling with incomprehensible options. MagicLantern provides a simpler HDR flow based on the “enfuse” tool (also bundled with Hugin), but I haven’t been too excited about the enfuse results with astronomical features. There are also some specialized options for astronomical stacking, but I won’t get too deep into them from here.
- Panorama stitching: I like Hugin. It is very powerful, produces great results (like this image), and is a free open-source option. It also comes bundled with useful tools like “align_image_stack” and “enfuse”, which are useful for a variety of purposes and interface well with MagicLantern.
- Astronomical tools: I’ve spent some time using tools designed for astronomical use. In particular, I’ve used the IRIS software and Keith’s image stacker, both of which provide a lot of advanced processing abilities and detailed options. IRIS is Windows-only but runs well under WINE (or Parallels on the Mac). I don’t think these tools are really applicable for wide-field photography, although they can be used to do some interesting things. I’m still playing with them, but certainly the most efficient post-processing strategy is to stick with the GIMP (or Photoshop) and Luminance HDR (or Lightroom).
Finally, some winning methods for GIMP/Photoshop processing:
- Unsharp masking: With this surprisingly simply technique, you can bring out extra detail as follows:
- Open the original image as a background layer.
- Duplicate the layer. On the new, duplicated layer, set the mode to “Subtract” and the opacity to 40%.
- On the new, duplicate layer, run a Gaussian blur. Repeat the blur several times.
- Adjust the brightness and contrast of the duplicate layer. You should see improved feature definition in the image.
- Adjust the background layer, the opacity of the duplicate layer, etc until it looks good, then merge the layers.
- Levels and Curves: If there is any light pollution, you can hide it somewhat by adjusting the levels or curves to suppress the lowest end of the histogram. It is also a good idea to bend the curve near the top, so that fully saturated stars are muted. This latter technique is often called “star shaping” and is frequently used in telescope astrophotography.
- Compositing: Many of the striking nightscape images that appear on Flikr and elsewhere are constructed by compositing separate exposures for the foreground objects and the sky. Tracking and stacking produce fantastic results for the sky, but smear the land into a muddy smudge. Conversely, a long exposure without tracking can reveal the landscape, but the stars will appear as faint streaks with reduced detail (in the extreme you can do star trails, which are nice). So the answer is to produce one image for the sky (probably involving many exposures for stacking), and a separate image for the foreground. The two images are masked and overlaid to produce a final, better product. Some photographers like to take the foreground image near sunset, when the landscape is still lit. I’ve even seen some composites where the landscape is taken in full daylight… Personally I prefer to take the landscape at night, lit by the stars or the moon or terrestrial lights. I think this creates the most realistic impression of the stargazing experience, which is my aesthetic philosophy for nightscape photography.
This concludes my summary of methods and techniques. Over the past year I’ve experimented with dozens of approaches, and finally crystallized my equipment and methods to the one presented here. I hope someone will find it useful, and I’m always happy to answer questions and to receive advice. Thanks for reading.