Long exposures are one of many means to photograph something in a way the naked eye doesn’t see it. Which is one of the reasons why photography fascinates me the way it does. The most popular images of this kind are night-time images of cities, in which driving cars paint long streaks of light through the frame.
This inspired me the other day, when I was looking at one of the many airplanes climbing into the sky nearby during an evening stroll. All airplanes taking off from Frankfurt’s southbound runway 18 fly towards our house, so in the dark evening sky, you can clearly see their bright landing lights and blinking navigations lights. Thus, the idea came up to give it a try and see what this can be turned into.
FOR THE IMPATIENT
A few days ago, the conditions were ideal: the weather was clear and dry. A few clouds were there, but they were high enough so that they wouldn’t be illuminated by the bright airport, and the climbing planes also wouldn’t immediately vanish into them. So I grabbed my gear and walked out into the fields.
There, I looked for a spot from which I had a good view on the planes as they take off, without having the bright streetlights of the next village in the image as well. Most of all, I wanted to avoid any cars passing by that would shine their headlights into the camera.
I had no idea up front what a good field of view would be, so I packed several lenses. I liked the view at a focal length of 35 mm the most, so I mounted the Sigma A 18-35 mm ƒ/1.8. I was able to capture several great night-time photos with this lens before. Since I never opened the aperture any wider than ƒ/5.6, this image could have also been taken with a standard-zoom kit lens.
With long exposures in mind, the camera was of course mounted to a tripod, and I had my remote shutter release with me as well. The main reason for using the cable remote is that I can lock the trigger button, so the camera takes several images in direct succession when set to continuous shooting mode.
This was a matter of trial and error. A few settings were clear from the start: I set the ISO value to 100. This reduces the noise in the image and makes for longer exposure times. As the light changes during dusk, I chose a fixed setting for the white balance, namely daylight. Finally, I focused manually on the horizon and switched the shooting mode to continuous.
Next, I worked out the shutter speed. Looking through the viewfinder and using a stop watch, I tracked an airplane from the moment its lights appeared above the tree line. It took about 80 seconds until it left the frame.
So, what is the best exposure time? Two contradicting factors need to be considered. On the one hand, a faster shutter speed generates more images. This also means there will be more gaps in the light trails, as the camera always makes a short pause between pictures. These gaps have to be closed manually in post-processing. This can be avoided, or at least minimized, by using slower shutter speeds. Unfortunately, this has an adverse effect on the image quality: the longer the exposure time, the weaker the light trails will appear.
I took a few test shots, and viewed the results using maximum magnification on the camera display. The two images below show the difference between a full-minute exposure and a half-minute exposure:
Finally, I settled for a shutter speed of 30 seconds. The light trails stood clearly out from the background, and a flight time of 80 seconds for each plane to cross the frame meant that I would have to close two gaps in each trail – a reasonable compromise. This also happens to be the longest exposure time the camera supports in manual mode. Even longer exposures require using the ‘bulb’ mode, which makes operating the shutter more complex.
That last value I set was the aperture. I set it so that the overall exposure of the image looked OK to me. The main goal was to make sure the sky didn’t become too bright, to simplify combining the images later. I started at ƒ/11, and then, as it gradually became darker, opened the aperture step by step to ƒ/5.6.
When everything was set, all I had to do was wait – not for long, though. As soon as I saw the lights of a plan emerging above the trees, I pressed and locked the trigger button on the remote shutter release. Thus, the camera took three pictures in a row. Often, the next airplane was already in sight at the end of taking the third image of the previous one. If not, I let the camera pause for a while.
Over a period of about one and a half hours, from quarter past nine to the last takeoff at 10:45pm, I took 75 pictures in all. Even though it was close to 70°F during the day, it cooled off rather quickly once it became dark. The warm jacket I packed now really came in handy, as did the beverages and reading material.
In retrospect, time passed rather quickly. After the last plane left, I packed everything together, used a flashlight to make sure I didn’t forget anything in the dark, and walked back home.
The next day, I went about assembling the final image from the individual pictures. The first step was to import everything to Adobe Lightroom CC. I applied a few adjustments to all photos: I activated lens corrections (lens profile and chromatic aberration), and increased the contrast and clarity to make the light trails stand out from the background even more.
Then I picked the image on which I liked the sky the most, and edited it to my liking regarding colors, contrast and details, to make it the background image. The result looked like this:
In Lightroom, I selected all 75 images, including the background, and chose “Photo” → “Edit in…” → “Open in Photoshop as Layers…” to transfer them over to Photoshop. This took quite a while, but then all pictures were layered on top of each other in a single project.
The first thing I did was moving the background layer all the way to the bottom, so that all other layers covered it. Then I turned all layers but the background invisible. The next step was selecting three images belonging to the same flight and making them visible again:
The crucial step now was to change the layer blending mode from “normal” to “lighten”. As the result, only those parts of each layer that are brighter than the underlying image are shown – in particular, the light trail drawn by the plane. The outcome of this first step can be seen in the image below:
This is already quite close to the desired result, but there are a few disturbing artefacts: First, there was another plane flying across in the image in the background, which caused the red and white dotted line near the horizon on the left-hand side of the image. Second, the stars in the top right hand corner are now duplicated, because they moved compared to the background image. And finally, the glow from the airport can be seen behind the trees.
Thus, I collapsed the three layers of the light trail into a single layer, and added a layer mask. Then I masked out all unwanted artefacts in the image – basically, I painted the entire mask black except for the light trail.
The final step was using the clone stamp tool to close the gaps resulting from taking three images. I set the sampling to “current layer”, and opacity and flow to 100%. Here’s the final result:
After completing one light trail, I hid the respective layer and started on the next trail. I worked on each one individually, because this simplified closing the gaps and removing unwanted artefacts. It also enabled me to adjust the brightness of each trail independently using levels adjustment layers.
The final step was to make all layers visible, collapse everything into a single layer, and export the final image:
TIPS & TRICKS
Some additional information in case you want to try this out yourself:
- When taking photos of this kind, it is better to take several images with shorter exposure time, and subsequently combine them in post-processing, than to take a single long exposure. This will improve image quality, and even more important, it reduces the risk of losing several minutes of action because, e.g., a car drives by and shines its headlights into your lens.
- I’ve linked two video tutorials below; one from Canon Australia on photographing light trails, and one from Jimmy McIntyre on post-processing them. They both used cars instead of airplanes, but the procedure is the same as in the image above.
- With long exposures, there are two factors to consider for the composition of the final image: the static background, and the patterns drawn by the moving lights. It takes some practice to imagine the final picture before actually taking it, so try it out when you find the chance.
- Taking such photos requires patience – for planning, for shooting, and for post-processing. I spent two hours on the field, plus another three one the computer. Take your time, it will be worth your while!
Recommendation: When you have an evening off – go for it! Grab your camera and your tripod, and go to the next street bridge, railway station, airport, local festival – wherever there are moving lights. This way, you can capture amazing and sometimes surprising motion patterns.
What I’ve learned: I’ve gathered some good experiences, for instance how the exposure time affects such long exposures and light painting images. The same goes for working with layers and the clone stamp tool in Photoshop.
- Light Trails: Learn how to get off auto mode (Canon Australia)
- Jimmy McIntyre: How To Add Car Light Trails In Photoshop (YouTube)
Picture Credits: All pictures – own images.