Pictures in Motion: Timelapses – Post-processing

Time Lapse

The first two parts of this series dealt with capturing the images for a time lapse with different camera types. This easily results in several thousand pictures for a longer clip. There are numerous software tools available for all operating systems to convert these into the final video. Basically, all these applications work in the same way; they differ in functionality, usability, and price. I will present the two approaches I mostly use for creating my videos: the quick-and-easy way using Adobe Photoshop, without further editing of the images, as well as the comprehensive workflow using Adobe Lightroom and LRTimelapse, which offer powerful tools to optimize the outcome.

HOW 2,000 PHOTOS BECOME A MOVIE

Let’s start with the simple case: all of the images are already available in JPEG format, as is the case when capturing time lapses with my old GoPro. If you are using Adobe’s Creative Cloud subscription, you will have Photoshop available in addition to Lightroom. In Photoshop, simply chose File → Open, select the first image, and then check the option for Image sequence. In the next step, Photoshop will ask for a frame rate. Afterwards, you can immediately export the movie in the desired format. If you’re using only Lightroom, many scripts can be found on the internet that will allow you to do basically the same thing.

Open image sequence in Photoshop
Open image sequence (“Bildsequenz”) in Adobe Photoshop CC

Furthermore, there are numerous image editing applications offering this capability. Without having tried them myself, I’d like to mention ImageJ, an open source tool written in Java, and the commercial tool Panolapse. Both are available for MacOS X as well as Windows.

There is one additional option for long-time Apple users, who still have a registration code for the Pro version of the old Quick Time Player 7 in their archives. You can download the last version of QuickTime 7 from the Apple homepage. You cannot buy new license keys for it any longer, but the old ones still work. After activating the Pro version, the option Open image sequence becomes available in the File menu. Just as in Photoshop, select the first file of the sequence, then choose a frame rate. A moment later, you can watch the video. Finally it can be stored as a movie file in Apple’s usual QuickTime format (H.264).

EDITING THE INDIVIDUAL IMAGES

Before the photos get merged into a video, it is a good opportunity to edit them. If you have shot in RAW format, you now have the full editing potential available. This allows for restoring a lot of detail in the highlights and in the shadows. In addition, you can optimize white balance, contrast, and color rendition to your liking.

However, this creates the challenge of editing the pictures consistently, to create a smooth video in the end. Hence, you need an editing tool that enables you to carry over the changes done on one image to the rest of the sequence.

In Adobe Lightroom this works best if you edit a photo from around the middle of the stack, and then synchronize the development settings to all pictures. This works very well, as long as the edits apply equally well to all images. As a part of this process, you should also crop the photos to a 16:9 aspect ratio. After exporting the images as JPEGs with a resolution of either 3840×2160 (4K) or 1920×1080 (Full HD), you can convert the sequence into a video as described above.

WORKFLOW WITH LRTIMELAPSE 4

If you want to make more advanced edits to the image sequence for the time lapse, a usual photo editing software won’t get you very far. The challenge lies in harmonizing the applied changes such that the resulting video doesn’t show any sudden changes in brightness or color, which occur when adjusting the shutter speed or ISO value during dawn. Videos of sunrises or sunsets are hence referred to as the “holy grail” of time-lapse recording.

For such occasions, I recently purchased Gunther Wegner’s software LRTimelapse 4. It works in combination with Adobe Lightroom and offers numerous functions which help to vastly improve the created videos. LRTimelapse is easy to use and offers some very powerful tools to manage adjustments to the original photos, and to handle changes of lighting conditions. LRTimelapse doesn’t modify the pictures itself, it just calculates the necessary adjustments and passes them on to Lightroom as meta data. The actual image processing is then done by Adobe’s Camera RAW engine. The workflow is as follows:

  • Launch LRTimelapse and open the folder with the RAW images for the time lapse. The software imports the files and analyses the brightness gradient. Based on that, it suggests a number of key frames; typically, four to eight. These can be adjusted as needed.
  • Using a special drag & drop button, the image sequence is then imported into Lightroom. Then you can set a pre-defined filter to show only the key frames.
  • These can now be edited to your liking with the full repertoire of Lightroom features. It is recommended to start with the first one, then sync the changes to all subsequent images. Then adjust the second image, if necessary, and again sync the changes to all subsequent images, and so on, until all key frames look the way you want them to. In addition, you should also crop the images to a 16:9 ratio. This will allow you to choose the image section yourself; otherwise, LRTimelapse will select the center part.
  • Once you’re done editing the key frames, save their metadata as files and return to LRTimelapse.
  • Now comes the magic: Based on the key frames, LRTimelapse will automatically calculate the necessary changes to all intermediate images. Thus, smooth transitions for brightness, color, and contrast are created. This will take some time, but you can see the results immediately in a preview clip.
  • LRTimpelapse offers a “deflicker” function for fine-tuning.  This way, I was able to achieve great results even when shooting in aperture priority mode and letting the camera determine shutter speed and ISO value automatically.
  • Store the new settings as metadata files (*.xmp).
  • In Lightroom, loading the updated metadata will apply the calculated changes to all pictures.
  • Finally, the export is started from Lightroom, using the LRTimelapse presets. As a start, all images will again be stored as JPEGs on your local hard drive. When processing 2,700 photos, this can take a couple of hours; at least on my six-year-old laptop. Once this is done, LRTimelaps renders the final video with the chosen settings (resolution, frames per second, video codec etc.). This works rather quickly, and can easily be repeated with different settings from the same JPEG sequence.

Gunther Wegner has a half-hour tutorial video (in English), where he introduces the functions and way of working with LRTimelapse in great detail.

EXAMPLE

The following video shows a sunrise over a period of four hours, with a picture taken every ten seconds. I captured this time lapse with the Canon 760D and the Radian 2. I set the aperture to 2.2 and let the camera choose shutter speed and ISO value automatically. The first images were taken at 5 seconds, ISO 400; the last ones at 1/4,000th second, ISO 100. The Radian 2 panned and triggered the camera.

The photos were edited using Adobe Lightroom and LRTimelapse 4 as described above. This created a video with smooth brightness and color transitions. The last step was adding the music, which is taken from YouTube’s free audio library, using Adobe PremierePro.

The thing that fascinates me even more than dawn itself in this video is the movement of the clouds. This is certainly not my last video of this kind; I will experiment more with capture interval, captured period, location, and weather…


CONCLUSION

Recommendation: The purchase of LRTimelapse was absolutely worthwhile for me, and I recommend it to everyone who considers working seriously with time lapses. A free demo version is available, which is limited to 400 images per sequence, but otherwise offers the full functionality. This will allow you to thoroughly evaluate whether the application meets your needs.

What I’ve learned: I think this series made it clear that capturing time lapses can be a lot of fun. Using the right tools, even difficult lighting situations can be mastered. Thus, small master pieces can be created with reasonable effort – literal “know how”.


LINKS:

Picture Credits: Title Image – Screenshot Adobe Lightroom CC; Open image sequence – Screenshot Adobe Photoshop CC; YouTube Video Sunrise – own images.

Photo Experiment: Light Painting with Airplanes

Night Traffic

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

Gear Settings
  • Camera
  • Tripod
  • Remote trigger
  • Appropriate clothing
  • Beverages
  • Reading material
  • Flashlight
  • Manual Focus
  • Manual Mode
  • ISO 100
  • 30 seconds
  • Aperture ƒ/11 – ƒ/5.6
  • Continuous shooting
  • White balance: daylight

OVERALL SETUP

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.

CAMERA SETTINGS

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:

Light Trail (60 sec.)
Detail view of a light trail with 60 seconds exposure time at 200% magnification. The dots painted by the blinking navigation lights are now barely visible.
Light Trail (30 sec.)
Detail view of a light trail with 30 seconds exposure time at 200% magnification. The trail is much brighter compared to the background, and the dots from the navigation lights are now clearly visible.

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.

SHOOTING

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.

POST-PROCESSING

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:

Night Sky
Night Sky – I liked the sky the most on this image. Thus, I used it as the background and added all other light trails onto it.

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:

Single light trail, part 1
Single light trail, part 1
Single light trail, part 2
Single light trail, part 2
Single light trail, part 3
Single light trail, part 3

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:

Adding one trail, before editing
The three parts of the one light trail, with the layer blending mode set to “lighten”, before removing unwanted artefacts and closing the gaps.

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:

Adding one trail, after editing
The finished light trail: The gaps have been closed, the trail of the landing plane has been removed, just like the duplicated stars and the glow the behind trees.

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:

Night Traffic
Night Traffic – The final image. Composed from 75 individual pictures, it shows the light trails painted into the evening sky by planes taking of.

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!

CONCLUSION

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.


LINKS:

Picture Credits: All pictures – own images.

Make and Edit Pictures of the Milky Way

Lonely Speck

Photographing the Milky Way was the motivation for me to finally get deeper into the art of photography. In preparation for a trip to Albuquerque, New Mexico, I had already bought a new camera. The next step was to learn how to make the best use of my equipment – and in particular, how to get the best out of the pictures afterwards, at home on my computer. What helped me the most in all of this was the YouTube channel “Lonely Speck” by Ian Norman, which I will introduce here.

Milky Way over New Mexico
Milky Way over New Mexico

PREPARATION

PLANNING

I spent about a week in Albuquerque, including a few open evenings. While looking for tips where and how to best see the Milky Way, I came across Astronomy Adventures. Peter has a dark site on a ranch up in the mountains between Albuquerque and Santa Fe, at about 7,800 ft. elevation, where he offers guided tours through the night sky with his telescope. Together with a couple of friends, we had the great luck to catch a clear night at new moon – perfect conditions. Peter’s explanations of the history of astronomy, while pointing out interesting stellar formations with his telescope, made for an unforgettable experience.

Back home, in a densely populated region such as Germany’s Rhein-Main area, catching a view of the Milky Way is not so easy. In order to see a decent amount of stars around here, one would have to go to the northern Black Forest, or to the coast of the Baltic Sea. The web site www.lightpollutionmap.info provides a very detailed overview on light pollution levels; check it out for dark places near where you live.

Full Moon Rising
Full Moon Rising

A natural form of light pollution is the moon. In a full moon night, there isn’t much else to see in the sky. There is a number of web sites and apps that help you out with what phase to moon is in, or when it and the sun set and rise respectively. A good recommendation is The Photograhper’s Ephemeris, which can be used for free on any desktop computer. Then of course the weather has to be right as well – the fewer clouds, the less humid and the colder it is, the better. And last but not least, the Milky Way or whatever constellation you are interested it, has to be visible on the sky. There are plenty of web site and apps for this as well; personally, I use Sky Guide for iOS.

EQUIPMENT

This topic can be quickly summarized. You’ll need:

  • A camera (the bigger the sensor, the better – however, even with a Micro Four Thirds camera you can take great pictures. With your cell phone… not so much)
  • A lens. That should fulfil the following requirements:
    • Widest possible angle, to capture much of the sky
    • Widest possible aperture (i.e., low aperture number, so that as much light as possible reaches the sensor)
    • For APS-C DSLRs, I recommend the Tokina 11-20mm ƒ/2.8 DX, which is what I am using
    • For other camera systems, I gladly pass on Stephan Wiesner’s recommendations: for mirrorless APS-C cameras, the Samyang 12mm ƒ/2.0; and for full-frame cameras, the Tamron 15-30mm ƒ/2.8.
    • However, expensive gear isn’t mandatory: even with your kit lens you can take great pictures, as will be shown below
  • Sturdy tripod
  • Optional: remote shutter release (if you don’t have one, you can use your camera’ two second delay shutter)

In addition: warm clothing (even in summer, clear nights tend to get cold), food, drinks, and a book. Also quite helpful: a flash light with a “night vision mode” (red lamp), so you can check or search something without blinding you or others in the dark.

TAKING PICTURES

Once everything is in place, line up your camera with the section of sky you’re interested in, and off you go. The most challenging feat is focusing correctly. In the dark, you have to focus manually, and simply turning the lens to “infinity” rarely does the trick. I usually look for a star that is bright enough to appear in Live View on the LCD screen, use the 10x magnification on it, and turn the focus ring until the star appears as small as possible. I take a few test shots in addition, zoom in, and then fine-tune as needed until the stars have become tiny pinpoints.

I typically start out with these settings:  11mm | ƒ/2.8 | ISO 1.600 | 25 Sec.

If you do not want to capture star trails on purpose, you cannot keep the shutter open for as long as you want – the earth rotates faster than you might think. Here is a rule of thumb for the maximum exposure time so that the stars still appear as dots: (500 divided by (focal length * crop factor)). The crop factor defined the relative size of your camera’s sensor compared to a full-frame camera. It needs to be taken into account because smaller cameras usually also have smaller pixels, hence are more sensitive to the movement of the stars. For a Canon APS-C camera like mine, the crop factor is 1.6 (it’s 1.5 for Nikon, and 2 for Micro Four-Thirds). So, with my camera and the Tokina 11-20mm, I can keep the shutter open for a maximum of (500 / (11* 1.6)) = 28.4 (rounded down: 25) seconds. Please keep in mind: this is a rule of thumbs. Check your images; you may find that you can keep your shutter open longer, or not as long, to get the desired results.

Always shoot wide open, to gather as much light as possible. Concerning the ISO setting, I usually start at 1,600. At least for my 760D, that is a good compromise between the amount of light gathered and the image quality. Once you’re all set, start taking pictures. And never take only one image of a particular target area; always take a series of pictures. I usually take 16 frames or more. This does take a while, but it drastically increases your post-processing options afterwards.

Milky Way and Andromeda Galaxy
Milky Way and Andromeda Galaxy

In closing, there is one important point to consider: when doing night sky photography for the first time, you’ll get easily tempted to make the pictures too dark. They’ll look great when you look at them on your camera’s bright LCD screen in the dark of night, but back home at your computer, you’ll be greatly disappointed. Make the pictures so that they actually look too bright at first! If your camera offers a histogram, use it. Of course, no parts of the pictures should be blown out (completely white), but there definitely should be information on the right hand side (lights) of your histogram. The more light there is in the image, the more information is available for post-processing – which brings us to the actual topic.

POST-PROCESSING

Ian Norman is a photographer living in California who specializes in astrophotography. Consequently, his YouTube-Channel offers a lot of information on this topic; in particular on post-processing the images. His tutorials explain the steps to be taken in Adobe Lightroom and Photoshop very well and in an easy to follow manner. When I edited my first night sky images, I always had my iPad running the video tutorial at hand. I paused, scrolled back and forth, and followed each step carefully. By now, I can do most of it without having to ‘cheat’.

EDIT SINGLE IMAGES IN LIGHTROOM

The big challenge is in achieving good contrast and bringing out all the details, so that the image still looks natural and not overloaded. You will notice that the camera sees a lot more stars than the naked eye does. However when manipulating the night sky, and in particular the colors in the Milky Way, there always is some artistic leeway of course.

I want to point out two of Ian’s videos in particular. In the first one, he explains how you can capture the Milky Way even under very difficult lighting conditions:

This also explains very well why it is better to make the images appear too bright in camera and then reduce brightness in post, than the other way around.

The second video walks you through the usual editing steps for night sky images in Adobe Lightroom. This also proves that you can take impressive pictures even with a slower lens, if you take some considerations into account:

Both videos describe the editing of single images. The advanced method is to merge several frames in Photoshop into a single image – but for this, the images are initially edited in Lightroom as well, before bringing them into Photoshop.

MERGING SEVERAL IMAGES IN PHOTOSHOP

Due to the physical limitations imposed on aperture and shutter time, it is inevitable to raise the ISO setting to 1,600 or even 3,200 when taking pictures of the night sky. This results in a visible amount of noise in the image, especially when zooming in. Using the default noise reduction algorithms included in most photo editing tools will result in losing a lot of details, such as smaller stars.

Now it comes in handy if you have taken several shots of the same area of the sky. The more, the merrier. In short, the trick is to stack and exactly align the images, and then to compute the average value for each pixel. As the stars will always be in the same places in all images after correct alignment, they are not affected. The image noise, however, is random and thus cancels out when calculating the median. If you combine four images taken at ISO 3,200 this way, the remaining noise will be comparable to a shot taken at ISO 800. For the Milky Way pictures you can see in this post, I have stacked more than 20 images each.

This video offers the detailed instructions for how to achieve this:

The particular challenge is the correct alignment of the images. If that does not match exactly, not only the image noise will vanish when calculating the media, but the stars as well, at least in parts of the image. As long as the pictures offer enough contrast, Photoshop’s auto-alignment will work very well. However, I had a number of occasions where the automatic alignment failed. This is no reason for despair, though, as there is a manual workaround:

What remains is the artistic design of the night sky. Ian explains how to best bring out the colors and details in the sky in this video:

This works not only for Orion, of course, but for every section of the sky that has to offer similar features.

Ian’s channel offers numerous other tutorials as well, which are all very helpful. If you have taken enough shots of a particular area, you might for instance consider turning them into a time-lapse video. Using the knowledge from these videos, I have taken quite a number of pictures of the night sky so far, and I am increasingly happy with the results. As with all other kinds of photography, practice makes perfect. So, then: wait for the next clear night around a new moon, and then take your camera out! Especially now during the long winter nights with their clear, cold air, the conditions are ideal…


CONCLUSION

Recommendation: Absolutely watch, then go out and try!

What I’ve learned: The knowledge what to consider when taking the pictures, and how to post-process them, is a lot more important than the equipment. Thorough preparation is important, as well as the necessary patience while capturing the images. The results in the end will be well worth the effort!


LINKS

FURTHER INFORMATION

Picture credits: Title image: YouTube Screenshot; Milky Way and Moonrise: own images

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