Tips and techniques
Time lapse photography can be a lovely way to spend a quiet afternoon somewhere. Whilst others might go fishing, I prefer settling down with a flask of tea and my tripod, giving myself the time to really appreciate the environment I find myself in. Time lapse is an important part of my work on Human Planet. Many of the sequences in the film will contain fantastic visual feasts revealing unusual events not normally visible to the naked eye. So I thought I’d give you a little time lapse tutorial which might help you make some of your own.
Before we start, it would be good to see an example of a time lapse film. Now, whilst I can’t yet show you any of the time lapses that I have shot for the Human Planet film, what I can show you are the outtakes. Such are the pitfalls of time lapse photography, that you often begin shooting one thinking that it will make a great clip, only to realize a few minutes after you start that it’s not going to be as interesting as you originally thought. At this point you have an executive decision to make… do you continue in the hope it gets better, or ditch it and start again? Well, allow me to offer up a third choice. Why not have a bit of fun with it and then post it on the internet? Here we have one such example from Ethiopia where I had decided that it would make gripping TV if the viewer could see the way a film crew assembles a jib, or camera crane. Not as boring as you might think! Watch on…
(You must forgive me for adding the music – it seemed apt)
OK, so it’s badly exposed and poorly composed, but it is nevertheless a time lapse film. You will probably want to start by producing something a little more conventional, so here’s the tutorial…
Firstly, you need a camera. For the sake of argument, I’ll assume you own a digital SLR camera. Everyone else, stop reading now, this doesn’t apply to you. Many digital SLRs have a time lapse function built into their firmware. Nikons certainly do, so have a good root through the menus before you consider purchasing an external intervalometer, which is the piece of kit that I use to shoot time lapses since I own Canon cameras. Canon do a great intervalometer – the TC-8ON3 which, apart from the fact you can’t set the number of exposures to more than 99, is a great tool for this job. I have owned a number of intervalometers over the years and can honestly say that this generic one works perfectly well if you’re on a budget. It has all the same features as the Canon at a fraction of the cost. I especially like the fact that you can easily programme it to begin a time lapse at a specified time, which means no late night trips out into the cold when you want to shoot the moon rising for example. Another piece of extra hardware you will need is a good solid tripod. I won’t recommend anything in particular – but one thing I have found myself is that it’s useful to have one with a hook on its lower side somewhere so that you can weigh down the tripod by hanging things from it (often rocks in plastic bags). This is particularly useful in windy weather – any slight movement of your camera during a time lapse sequence will spoil the desired effect. Lastly, you may need to get some Neutral density filters (ND filters). Put simply, these are tinted glass filters which block out light from your lens allowing you to make longer exposures in daylight conditions. I normally use an ND 3.0 filter which, to the naked eye looks like a piece of black glass and allows me to make very long exposures in the midday sun. Many photographers also use these filters when shooting daytime landscapes in order to blur certain moving elements of their picture – most commonly, waterfalls or the sea like this.
OK, now onto the practical side of things. First thing… Choose your subject. The most important thing to bear in mind when shooting a short time lapse is ‘what will this scene look like in the future?’. The more you shoot, the better you will get at predicting interesting time lapses. More often than not, it is easier to simply train your camera on a particular panorama and then shoot more frames than you need (the more the better). Then you have the option to select the most interesting section of the time lapse and create a film out of just that bit. The easiest and most rewarding thing to begin time lapsing with is the movement of clouds through the sky. If you live somewhere really sunny and cloudless, then why not start with the movement of shadows cast by the sun’s movement across the sky.
Once you’ve framed your shot with the camera firmly on your tripod, you’ve now got to decide how much interval to leave between each frame. I’ll use the sun and cloud examples since they both need different intervals. Basically, timelapse movies run at between 24 and 30 frames per second. British TV runs at 25 frames per second, so that’s the figure I use since my time lapses are designed for inclusion in a TV programme. At 25 frames per second (fps), 250 exposures will produce 10 seconds of movie, so if you want a 10 second clip on TV, you need to set your intervalometer to shoot 250 frames. If you can’t specify that on your intervalometer, you must instead calculate how much time it will take to shoot 250 frames and then time your sequence with a stop watch (eg. at a rate of 1 frame every 3 seconds, it will take 250 x 3 = 750 seconds or 12.5 minutes to complete a 10 second time lapse film).
Put simply, the shorter the interval between each frame, the more slowly the action will move in your film. Using the shadows and clouds example again – clouds will almost definitely tend to move much faster through the sky than a shadow cast by the sun will move across a landscape. So, we normally set a shorter interval between shots when time lapsing clouds, and a longer one when shooting the sun’s path across the sky. Practically speaking, this means roughly 1 to 15 seconds for clouds (depending on the wind speed), and 30 seconds and above for the sun’s movement. These are my generalizations of course. There are no hard and fast rules governing time lapse intervals. The interval you set is totally up to you and how fast you want the action to move in your clip.
It’s worth mentioning that if you are shooting an unfamiliar situation it is often a good idea to shoot your time lapse with a shorter interval than you may expect. This way, you will have the option to remove images from the final sequence at a later date if you decide in hindsight that the action looks better speeded up, remembering to make your new interval length divisible by your original one in order to make the post production simple (eg. if you expect a 4 second interval but you’re not certain, shoot with a 2 second interval and then afterwards you can easily revert back to the 4 second interval by removing alternate images from the sequence. Remember though, that the exposure length you choose for a 2 second interval will not necessarily produce smooth and realistic movement in your 4 second interval sequence).
There is one final thing to say about interval length. All digital cameras need a certain amount of time to process and download image data to the memory card. Cameras contain their own RAM memory, called the buffer, in which images are temporarily stored before being written to the card. Having a buffer affords the camera the ability to shoot frames rapidly in succession but there is a limit to the number of files they can handle before the memory fills to capacity and the camera automatically disables its shutter in order to give the processor time to free up more space in the buffer.
If you are shooting a time lapse with a short interval length (eg. 1 second) then at a certain point your camera’s processor may struggle to keep up with the amount of data that it needs to continuously write to the memory card. The result will be a slight pause in shooting every now and then which will distort the continuity of your sequence. Similarly, if you are shooting RAW files, long exposures (eg 1 minute) or pictures containing excessive detail then your camera’s buffer will also need more time to process the image data. To combat this problem you have a few solutions. Firstly, reduce the resolution of each frame by decreasing Image quality in your camera’s menu options. Secondly, invest in a higher quality memory card that can handle faster data transfer rates (written as MB/s or ‘megabytes per second’ on the card). Or lastly, you can upgrade your camera to a better model which has a higher buffer rate.
So, since we’ve decided upon the interval and length of our clip, we now need to talk about our exposure. In the beginning, set your camera to its fully manual mode – you need to fix both your aperture and shutter speed so that each frame is exposed identically. I’ll talk about auto exposure time lapses later on and also the problem of time lapse flicker in a manual mode when we get onto the more refined aspects of time lapse photography. For now, we’re using only manual settings with the auto focus and auto white balance functions in our camera disabled.
Deciding upon the aperture setting depends on two things – how much depth of field do you want and how fast (or slow) you want your shutter speed to be. The latter of these two will probably be your bigger concern in the beginning. Shutter speed in time lapse films is a very important factor. If you shoot with a fast shutter speed (eg. 1/100th second), the movement in your final film will tend to look less realistic than if you shoot at a slower speed (eg. 1/2 second). If you want to know what I mean, play any action movie on your computer and then freeze frame it during a fast moving sequence. You will notice that all the action is blurred when you view only one frame. However, when you run a sequence of blurred images one after the other, the illusion of movement is created and the blurring is ignored by your eye. Of course, any static objects in that sequence will remain pin sharp no matter how long the exposure as long as the camera is completely still on the tripod.
Roughly speaking, your shutter speed should be just under half that of your interval. So, for a 3 second interval, a 1.3 second exposure is great. At longer intervals this rule ceases to apply, so for example, when shooting the stars at night, a 30 to 60 second exposure is usual depending on the star cover (at ISO 800, f2.8) with a 5 second interval between shots for super realistic movement. If you expose too long, the path of each star may begin to appear as a line in your picture and can look a little unrealistic. However, if it’s an interesting effect that you’re after, then expose as long as you want. To be safe, when you are shooting anything moving relatively slowly (eg clouds) for the best results, use a 1 to 2 second exposure for short clips. If your shot has people or cars moving through it then it is imperative to use this kind of exposure length otherwise your moving objects will appear as ‘blips’ on the screen, creating a very unrealistic time lapse. As a general rule of thumb, if you are leaving a long interval between each frame (eg. 30 seconds or above) then it is extremely important to use a slow shutter speed in order to make the movement of natural objects run smoothly between frames. Bear in mind also that time lapses containing people don’t generally work very well with large intervals even if your exposure is long. Experience will be your best teacher here and as you practise you will discover what works best for you.
Shooting longer exposures in daylight will require you to set your ISO to the smallest value (ISO 50 or 100), and if you still can’t achieve a slow enough shutter speed, you will need to use the neutral density filters I mentioned earlier. My ND 3.0 filter will add 10 (f) stops to a lens. In reality, this means you can easily shoot a 3 second exposure at f2.8 in bright sunlight.
As you get more particular about the results of your time lapses, you may want to shoot at wider aperture settings in order to eliminate dust marks from your final images and so reduce the amount of post production necessary. Remember, at f22 your camera will bring quite a lot into focus including the marks on your lenses and filters. Using ND filters will solve this problem if it arises.
Great! We’re now ready to shoot our time lapse.
1. Manual settings on your camera
2. Set your ISO to its lowest if shooting in daylight without ND filters
3. Solid tripod = no camera movement
4. Longer shutter speed = more realistic movement (up to a point)
5. Set your interval according to how fast you want the action to move
6. Check that your memory card has sufficient free space for your images
7. Make sure you have enough battery power to last the duration of shooting.
Now pop the kettle on, relax and after your camera’s shot about 250 images, we can create a short movie out of them.
Creating the movie
After your camera has shot sufficient frames to create a long enough movie, download your images from your camera to a computer. One of the simplest ways to create a time lapse film out of your folder of images is to use Quicktime Pro. Unfortunately, the free version of Quicktime 7 has the time lapse function disabled, so you will have to search the internet for another piece of software to sequence your images if you don’t want to pay $20 for a Quicktime Pro upgrade – check Google for alternative software… there’s loads (Here’s a couple of free ones for starters: Virtualdub, Photolapse3)
Firstly, make sure all your images are numbered sequentially in one folder with no other files in that folder. Your camera will automatically number your files as you shoot them. (eg. for Canon users IMG_4398.JPG, IMG_4399.JPG, IMG_4400.JPG and so on).
Now, in Quicktime Pro, click on the ‘File’ drop down menu and select ‘Open image sequence’. It will prompt you to select a file. Find the folder containing your timelapse images and click on the FIRST one in the sequence, then click ‘open’.
Now wait until a movie box appears on your screen – this is your time lapse film. If you shot your images at a high resolution then your computer may now struggle to play this clip as a movie without first compressing it and saving it at a smaller file size. If this is the case, I suggest that you click on the ‘file’ drop down menu and click the ‘Export for web’ feature. This will create a folder containing an MPEG 4 movie file (your_movie.m4v) which will run very smoothly.
That’s it – you have a time lapse film – now start experimenting with different situations!
Here’s another fun time lapse that I shot in Mongolia recently. About an hour’s shooting using a 3 second interval, 1.3 second exposure with an ND 3.0 filter on a Canon 16-35mm lens.
Time lapse flicker
Time lapse flicker is an anomaly that appears in some time lapse movies where a slight flicker is visible as the movie runs. This happens because of extremely small fluctuations in the exposure of each frame caused by the camera’s aperture opening and closing to a minutely different degree each time a frame is shot. The aperture on your camera is a moving mechanical device, and as such it is normal for it to exhibit these fluctuations in everyday shooting but it is only during a time lapse movie that they become visible since it is necessary for every frame in the movie to be identically exposed. In my experience, Nikon cameras are more prone to this than Canons. Shooting subjects such as back lit clouds seems to cause this more than ones with softer lighting conditions.
There are a couple of things you can do to combat time lapse flicker. Firstly, use an old, fully manual lens on your digital body – one of those lenses where the aperture control ring is on the barrel of the lens. On the lens mount, you need to jam something (a small piece of plastic is good) into the gap on either side of the small lever that controls the aperture size in order to fix it at one position. This way, the aperture is stuck at the f-stop you designate and cannot open and close as normal when the camera shoots a frame, thus eliminating any potential fluctuations. This method is a bit fiddly and it means that you have to predetermine your aperture before you attach the lens to the body. All in all it’s a bit of a pain. A much better idea is to run some software on your time lapse images which evens out the exposures to take away the flicker. I’ve heard that GBDeflicker is very good at this, but I’ve never used it. All my time lapses go through post production at the BBC and to be honest, I’ve no idea what they do to them.
Transitional time lapses and auto exposure
Sometimes you may want to shoot a time lapse film that spans two very different lighting situations – most commonly, when shooting any scene during the transformation from daylight to night time. To do this successfully, you must either devise a way to change your aperture/exposure/ISO during the jump to the new lighting situation, or set your camera to auto, and let it work it out for you. The former is a delicate science and is only worth attempting after you have shot quite a few transitional time lapses, but if you possess 2 camera bodies, the easiest way to do it is to use your second body to take light meter readings from a grey card positioned in neutral light near your time lapse camera. By monitoring the readings from this second camera, you can manually adjust the setting on your shooting camera as the time lapse is running. There is probably a way of rigging an external light meter to your shooting body in order to make this happen automatically but I’ve never come across such a device before – check Google, I’m sure somebody has done it somewhere.
UPDATE: A lovely little device now exists called a Little Bramper which will automatically change your camera settings to create a smooth transition between extremes of light. I haven’t used it myself but from the looks of their Video Tutorials, it is the perfect gadget for the job.
If you decide to use auto exposure then the best scenes to shoot are those with ‘flat’ lighting conditions, meaning no great contrasts of light across one frame. Using the auto exposure function on your camera is not a reliable way to shoot a transitional time lapse but, if nothing else, it will certainly give you some results that will be helpful hints for the time when you begin to devise a way to adjust your exposures manually. Remember, when exposing automatically, make sure you set the light meter to read an average value for the whole frame, rather than any kind of spot metering unless you are absolutely sure that you can choose a spot in your frame that will make a smooth transition through your changing lighting conditions. If you spot meter and your image is not ‘flat’ then the light meter reading will be thrown out by localized light conditions fluctuating in the part of the frame that records the reading, such as the passing of the moon for example or changing cloud contrasts. The result will be a chaotic variation in exposure across the time span causing flicker. My advice if you wish to shoot a transitional time lapse with auto exposure is to begin with a frame pointing at a part of the sky which never sees the sun or moon crossing it and preferably with a uniformly constant covering of cloud. This will give you the ‘flat’ conditions that you need to get the most consistent exposures. Remember that your camera may not be able to do an auto exposure over 30 seconds long, so bear this in mind when setting your ISO if you wish to see the stars at night time, otherwise you will need to set your exposure with the intervalometer and leave the camera on ‘bulb’. Even after all these precautions, a time lapse film created using auto exposure will inevitably contain flickering, so you might like to use GBDeflicker or such like to flatten out your exposures in post production.
Panning time lapse
As you do more and more time lapses, a time may come when you want to do a panning time lapse film. This is a time lapse during which the camera actually moves slowly causing the framing of your image to change over time. In the BBC documentary Planet Earth this was done very successfully in, among other situations, the filming of creeping plants growing in the jungle. There are two ways to achieve this effect. The first, is to use a movement rig that you attach your camera to and program it to move slowly over the course of your time lapse. This can be an expensive specialist piece of kit, so a much easier way is to shoot your images at the highest resolution setting on your camera, and then in post production, use software to pan across the movie frame giving the impression that the camera was moving through your scene. The resolution of TV is such that with a modern digital SLR it is quite possible to crop a time lapse image substantially and still get the correct resolution for broadcast TV. You will need to use Final Cut Pro or similar software to create this panning effect through your time lapse. The draw back to using this method is that you may lose or distort the optical characteristics of your images if you are shooting with wide lenses , which are the most common choice of lens for panoramic time lapses. So if you plan on trying this technique you might be advised to shoot your images with a slightly longer lens. I would suggest 50mm or above to be safe.
As far as I know, the cheapest way to get hold of a panning time lapse rig for your camera is to use a slightly modified electronic telescope mount and controller. You’ll find a very useful video explaining this setup HERE. We used this rig in Africa last month and it worked perfectly
If you’re interested in really high-end panning time lapse, take a look at this behind the scenes video from the BBC’s documentary Life to see just how far it is possible to push this art form.
Update: As you can see, that clip is no longer working. Click HERE to see the clip.
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