Nighttime photography is a lot of fun, gaining greater popularity and attracting more and more photographers. I’ve been exploring the various techniques and want to share with you the one I like the most. Now, I don’t pretend to be a master at nighttime photography. I’ll leave that up to the legends like Wally Pacholka. But we can still have a lot of fun and come away with some very nice images.
I must add this disclaimer through. Serious nighttime photographers use specially modified digital cameras that capture more of the infrared spectrum, that portion of the light spectrum that our cameras do not pick up. If you’re interested in really pursuing nighttime photography you’ll want to get your camera modified. But be forewarned, once modified it can only be used for nighttime photography and the modification is a one-way street.
But even those of us who do nighttime photography along with daylight photography can still get some great photographs.
Now, there are two basic types of nighttime shots – star trails and what I’ll refer to as the nighttime sky. The latter tries to stop the stars’ motions. There are a lot of different techniques for capturing star trails that range from a single very long exposure to multiple exposures of intermediate length (e.g., 1 or 2 minutes) to a series of relatively short exposures (e.g., 30 sec). Nighttime sky photographs are limited to relatively short exposures.
The technique I want to share with you is the star trails technique that uses relatively short exposures. This has the advantage of being able to create star trails and nighttime sky photographs. The exposures are taken one after the other without any intervals between them.
So here are the simple steps for doing nighttime photography using this technique.
Step 1 – Before you Head Out
Before you head out for your nighttime shoot you want to make sure you have fully charged batteries, a memory card with enough storage (preferably empty) and a remote shutter release. You’ll also need a flashlight and/or headlamp. If you want to do light painting you’ll need a flashlight that has an output of at least 125 lumens. Warm clothes and hand warmers are also somewhere between nice-to-have and essential. You also want to make sure you can operate your camera in total darkness.
Step 2 – Configure Your Camera
You’ll need to configure your camera for nighttime photography. You need to shoot in Manual exposure mode, manual focus and manual white balance. I normally set the white balance to Daylight and correct any white balance problems in Lightroom or Photoshop. That suggests that I’m shooting in RAW and not JPEG which is the case. You also need to set your shutter drive on Continuous. The technique I’m sharing with you here involves taking one 30 sec exposure after another by locking the shutter for the duration of the shoot.
Lens selection is also important. Most nighttime photographs will require a wide angle lens. I like to use a lens in the 17mm to 24mm range on my full frame sensor DSLR. (Note: there are more reasons to use a wide angle lens as we’ll discuss below.)
Now, where are come camera settings that may appear counter intuitive but they are important. First, make sure High ISO Noise Reduction is turned OFF. Leaving it on will cause delays between exposures that will result in your star trails looking like dotted lines. Second, make sure Long Exposure Noise Reduction is also turned OFF – for the same reason. (You’re probably cringing now because of the potential for noise. Yep, you may get noise. But the noise reduction adjustment in Lightroom is up to the challenge. Slam Luminance Noise Reduction to 100 and it’s gone.)
Step 3 – Compose
When you arrive on location you’ll want to work out a composition. With this technique we’re going to end up with star trails and nighttime sky images. Most star trails images are interesting if you include Polaris – the North Star. So you want to find a subject that has Polaris above and behind it.
Also, if you plan to do light painting you’ll want an interesting foreground object. You have lots of options when composing the foreground object and Polaris. Use your imagination.
Select the focal length you want to use and take some test shots to dial in your composition.
Step 4 – Determine Exposure
I find that I need a lot of test shots before I’m ready to actually start. One of the first things to test is exposure.
As a rule of thumb you will shoot wide open at a high ISO. But beyond that, the first thing to determine is your shutter speed. The stars are constantly in motion but if you use the correct shutter speed you can ‘stop’ their motion. By that I mean the motion is so slight that it’s virtually unnoticeable – even though it’s still there.
There’s a simple formula for determining your shutter speed. It depends on the focal length of your lens. The formula is
600 / focal length (mm) = exposure length (sec)
So if you’re shooting with a 20mm lens the exposure length is 600/20 mm = 30 sec. If you’re shooting with a 100 mm lens the formula works out to be 600/100mm = 6 sec. This is one of the reasons why you want to use wide angle lenses. Now here’s an interesting point. This formula works with the actual focal length of the lens, not the apparent focal length. So it doesn’t matter if you’re shooting full frame or crop sensor, the calculation is the same.
The rule of thumb I follow when it comes to focal length, then, is 20mm or wider. Then I can use the camera’s maximum exposure length of 30 sec. In fact, this technique relies on the exposures being no longer than 30 sec.
So, for this technique my starting configuration is the maximum aperture of the lens, a 30 sec exposure and high ISO. I normally start with ISO 3200 on my f/4 17-40mm lens. I take a test shot and then decrease the ISO by one stop to 1600 and take another test shot. After each shot I examine the image on the LCD screen. The histogram is going to be slammed all the way to the left. But this is one of the rare instances where I evaluate the exposure using the image instead of the histogram. I want to make sure the stars are clearly visible. Quite often I end up with an ISO of 800 for an f/4 lens.
Step 5 – Focus
As you can imagine, this is challenging to do in total darkness. Live View is useless because there’s not enough light hitting the sensor. There are several techniques you can use, most of which involve looking through the viewfinder. However, all of these techniques are complicated by the fact that you can’t zoom in on an object, focus and then zoom back out. Our zoom lenses do not hold the focus throughout the entire zoom range and we’re shooting wide open so we can’t rely on depth of field to correct for any shifts in the focal point. So objects are very small.
With that in mind, if there’s a bright moon you can try to focus on that. Or, if you have a foreground object and a bright flashlight, you can illuminate the object and focus on that. The foreground object needs to be 50 to 100 feet away through so that is at the effective infinity distance for a wide lens.
Failing all of this just manually set the lens to a little shy of the infinity mark and take a test shot. View the magnified image on your LCD screen and make whatever adjustments you need to make. You want the stars to be little pinpoints at full magnification.
Step 6 – Light Painting
If you plan to do light painting (as is possible with this technique) this is the time to practice. Light painting can be a tricky deal so it’s best to rehearse so you know how much light to use and how to get the coverage you want. We’re going to do the actual light painting at the end of the shoot but you want to dial it in now.
Step 7 – Final Check
Before you begin make one final check because once you start you’re committed. Double check focus, exposure, white balance and Continuous drive mode. Confirm that High ISO Noise Reduction and Long Exposure Noise Reduction are both turned off.
Step 8 – Capture the Shots
When everything is ready, everyone turns out their headlamps and you start shooting. Press your remote shutter release and lock it into place.
Now it’s time to sit back, relax and enjoy the universe rotating majestically above your head. It is a time for quite conversation and perhaps some inspiring music to match the grandeur of what you’re experiencing. I set the timer on my iPhone to alert me when the time is up. Don’t turn on any lights to spoil the mood or the captures.
Now, since we’re shooting both star trails and nighttime sky photographs the length of the ‘exposure’ is really determined by how long we want the star trails to be. I find that 30 minutes is not really long enough. But between 45 and 90 minutes ill product very satisfying results.
Step 9 – Time Up
When time is up, don’t jump up, turn on your headlamps and turn off your cameras. Take this opportunity to do the light painting you practiced earlier. Do a couple of frames so you have some options later on. This gives you a fantastic opportunity to have a star trail photograph with a light painted foreground object.
Once you get one or two light painting frames it’s time to stop the captures.
Step 10 – Post Processing
I won’t go into post processing in any great detail here except to point out how we turn those scores of individual nighttime sky photographs into one star trail. The first step is to import the RAW files into Lightroom. You might be tempted to work on the RAW images at this point but, while that’s OK, I’d keep it to the bare minimum. For example, I’d make sure Blacks was set to 0 and the contrast in Tone Curve was set to Linear. You may need to apply some noise reduction so do that now. Any adjustments you apply to one of the image needs to be Sync’ed to all the images.
Next, export all of the captures you want to include in the star trails image. I export them as TIFFs although you can export them as JPEGs if you prefer. Also, I like to put them in a subfolder called ‘Star Trails’. If you want to include a light paint image, select the one that works best and export just that one.
The next step is to stack all of these images. There’s the hard way and the easy way. The hard way is to manually stack them in Photoshop. The easy way is to use one of the free programs available for just this purpose. I like Markus Enzweiler’s StarStaX. It works on PCs, Macs and Linux machines, it’s fast, it’s flexible and it’s free. Point the program to the folder that contains the exported files and watch it do it’s magic. You can see the star trails image materialize right before your eyes. It’s very cool.
There’s another thing you can do with those exported TIFF files. With Apple’;s QuickTime Pro you can create movies of the stars moving across the sky. You can upgrade QuickTime to Pro for about $25.
Benefits of This Approach
There are a number of benefits to this approach. First, you get the best of both worlds – star trail and nighttime sky photographs.
Second, if something goes wrong all is not lost as it would be with a single star trails exposure. And things can go wrong. Your battery can die (cold kills the power and battery life), your memory card can fill up, your lens can fog over and so on.
Third, if a remarkable event occurs during one of the 30 sec exposures you can create a cool nighttime sky photograph. That could be a shooting star, Northern Lights, a passing space station or perhaps even a supernova.
By capturing a few light painting frames at the end of the exposure you can create a star trails and light painting photograph. I haven’t seen very many of those, at least not yet.
The disadvantage is that you’ll have a lot more files to deal with. A 45 minute exposure will generate 90+ files. And if you’re shooting one of the full frame sensors where the RAW files are anywhere from 20MB to 30MB each that’s a lot of storage. But hey, isn’t that why we have 16 GB memory cards and terabytes of external drives.
So, give it a try. You’re going to have fun with this one.
Spirit Tree Star Trails
Spirit Tree Night