Before we launch into the tricks, let’s first get some terminology straight.
- Long Exposure – in my vernacular this is an exposure over 30 seconds – the limit of most DSLR cameras.
- TimeLapse – a series of photos taken over time that compresses (or expands) the actual time when made into a movie. Usually all the exposures use the same settings. An event that takes 3 hours can be distilled into a 30 second video. An event that takes fractional seconds – like a balloon popping – can be shot at high speed and expanded into a movie that lasts much longer. Usually expanding the time is called “Slow Motion”.
- StarTrail – like its timelapse brethren, implies a series of shots taken over time and combined into one exposure to show the star motion OR a StarTrail can be created from a SINGLE very Long Exposure.
- Bramping (aka Bulb Ramping) – a timelapse techinque in which the length of the exposure is changed over time to accommodate the setting sun, rising moon – anything that involves a gradual change in the ambient light.
How is a Timelapse different from a Star Trail?
The two are not different, except that by intention a Star Trail created from multiple exposures requires a minimal interval between one shot and the next or gaps result. For a timelapse – which can be taken at night or day – the key is having a regular interval between each shot. Changing the interval between shots has the effect of warping time.
Ok, Got it. Tell Us About the Tricks
Why would you want sub-second intervals? For one, to catch as many meteors as possible. The second or so that the camera spends with it’s shutter closed is a second you might miss that brilliant fireball. Another reason to keep the interval REALLY short is to reduce or eliminate gaps in star trails. But sub second intervals are the hardest trick of all. There are almost no intervalometers that allow setting an interval shorter than one second, and even if it’s possible many cameras can not handle sub-second intervals. However, there are a few devices that can do sub-second intervals: Trigger Trap for one. The best way to find the shortest possible interval is to set up the camera and try! Set the interval to say 700 ms and see if your camera can run off a sequence of 15 to twenty 30-second shots without missing a beat. If that works, set the interval to say 500ms. Note that the minimum interval will depend on the camera, as well as the size of the image, and speed of the memory card. Once you find the minimum, leave a little extra time and use that. My Canon 5D Mk II was happy with 450 ms intervals between shots. That’s HALF of the waiting time of one-second intervals.
Shake Reduction – Mirror Lock Up
Many people worry about mirror slap. Mirror slap occurs when the little mass of the mirror “wiggles” the camera enough to blur long-ish exposure shots. Mirror slap is particularly pernicious in the 1/4 to 2 second exposure length. It may also be a problem if you have your camera attached to a delicately balanced telescope at high magnification. How do you solve the problem? It depends on your camera, but there are several approaches to try:
- Leave live-view on (which will eat batteries and may result in excessive warming of the sensor)
- Use the camera self-timer in mirror lock-up shooting mode. Most cameras will behave properly if your exposure length is not bulb. That is, they will move the shutter, wait for the delay to expire and then take the shot. Remember to allow a delay that is at least one second longer than the shot length plus the self timer delay. For example, let’s say you want to take as many 24 second exposures as possible but you need at least 8 seconds for mirror slap to stabilize. Set the camera to 24 second exposures with a 10 second self-timer. Then set the intervalometer to take a 1 second(!) exposure every 36 seconds. The reason for the 1 second exposure is to allow enough time for the shutter release to be recognized while the 36 second delay allows for 10 seconds of timer, 24 seconds of shot and a 2 second safety buffer.
- See the Maximum Shots, minimum interval trick. But instead of 1 second delays, change the length of the exposure to the amount of time you need for camera stability + 1 second.
- Want to do shake reduction in BULB mode and without a self-timer? Set the exposure length to the desired amount of time and use a short interval. With mirror lock-up on, you’ll get every-other exposure at the desired length. Note: this is the most “iffy”mode as it depends on your camera behavior.
- Finally for shake reduction in BULB mode WITH a selftimer, set the intervalometer as normal, but set the length of exposure longer and include the self-timer interval. For example to take 60 second exposures with a 10-second self timer, set the exposure length on the intervalometer to 70 seconds.
Variable Length Shots
While this technique seldom works well, you can allow the camera to determine the exposure length via metering. All you have to do to make this work is to have the camera take 1 second exposures (as before) no more frequently than the longest exposure you expect to take. Some fancier devices, like the Trigger Trap and the CamRanger can even be configured to change the exposure length over time. This feature is called “Bulb Ramping”.
Extended Self Timer
Got a big group shot and no wireless remote. Not a problem. Set the camera to a short (e.g. 2 second) self-timer delay, and set the shot delay to say 20 seconds – or as long as you need to safely climb on top of the human pyramid to get that perfect shot. Since you can allow multiple shots, you’ve all got plenty of time to change your poses, or re-architect your human pyramid. We use this trick all the time when we’re conducting workshops. It allows us to set up our camera and walk away while we instruct. We leave enough time to set up for the shot. Most cameras will blink or flash to let you know they are about to take a picture so everyone can time that cheesy fake smile. Note: If using a Flash, you can lengthen the interval between shots to give the flash extra time to recycle.
Maximum Shots, Minimum Interval
When not in Bulb mode, it can be maddening to not have the Intervalometer and the camera in sync. Set the camera to 20 seconds and the intervalometer to 19 and you’ll miss about every other shot. Bummer. Here is a trick to maximize the number of shots and not care much about the actual exposure time. Set the intervalometer to take one second shots with one-second intervals between each. The maximum shot-to-shot delay will be two seconds that way and it doesn’t matter what your exposure length is on the camera if it’s NOT bulb.
What if you want BULB mode? How do you configure that?
Answer: (Select the text below to reveal)
That’s the normal intervalometer configuration mode. Camera is bulb, length of exposure is whatever you need and the interval should either be 1 second, or exposure length PLUS one second depending on the intervalometer.