Join Richard Harrington for an in-depth discussion in this video Choosing the right interval for shooting, part of Time-Lapse Video: Nighttime.
- I'd like to revisit the concept of Interval. Earlier, we talked about the overall exposure time when you were shooting, and that's essential that you get it balanced right. Remember, keep the camera open too long, and you get streaks that you might not want. But the Interval can be particularly tricky with nighttime time lapse. For example, if I'm just using the camera with its built-in Interval timer, it's pretty easy. If you're gonna be shooting something that's a 30 second exposure and you put a two second Interval, well, then the camera's gonna make sure that it waits for two seconds after it completed the previous shot.
The great news with the built-in Intervalometers, or if you hack the camera with something like Magic Lantern, is that it will make sure that the shot has completed before it starts the next one. But if you're using an external Intervalometer, this can be a bit tricky. I did a lot of shooting using Triggertrap, controlling my devices with an iOS tablet or my phone, and this worked great. But the challenge was is that it was sending a pulse to the camera to take the shot, and sometimes if the camera settings weren't exactly right, it could get in the way.
One way around this is to put the camera in bulb mode, so the external Intervalometer is totally driving the camera. Where it gets most complex, though, is when using a unit like this. Here is my eMotimo, and besides working off of the top of a tripod, it can also be attached to a motorized slider. And I love this. It gives me the ability for three-axis time lapse, like some of the shots you're seeing here. This allows you to have three types of movement. Not only can the camera move side-to-side on the rails, but this head can pan and tilt, and that's really quite cool.
The challenge, though, is in the communication. So what needs to happen is a couple of things. First off, it needs to send a signal to trigger the camera. This is going to trigger the camera and make the camera shoot. Then you need to allow a little bit of time for that file to actually write to the memory card. So depending upon the speed of the card, this can affect that. Maybe a second is enough. But if you're gonna be using a motorized slider, you then want the camera to move. We often refer to this as shoot-move-shoot.
So it takes the shot, closes the aperture, then once it's closed, the unit will advance, and move along the geared teeth. You then want it to be stable and have no vibration before the next shot is fired. As such, it gets a bit trickier. It becomes essential, as you're shooting these types of time lapses, that you take into account all of the other factors that can affect the Interval. To break that down one last time, using the built-in Intervalometer, easiest mode out there.
The camera will typically not fire the next shot until it knows it's ready. Stepping up to an external control, well, usually adding one or two seconds is gonna be enough of a delay. And that external control just needs to compensate for the card capturing the image and the buffer clearing. And because you have a higher buffer capacity, this often will not be much of an issue on modern cameras. Where it gets most tricky, is using the motorized sliders for nighttime time lapse. Now you need to accomplish not just the shot, and not just the transfer to the memory card, but also the movement of the camera and then the settling, so there's no vibration that could affect the shot.
Now, the good news on a long exposure nighttime time lapse, if there is a little bit of movement or vibration, it's only gonna be for one or two seconds of that 30 second exposure, so you may not even notice it. But taking the time to make sure that your Interval and the settings that you load into the external controller are matched with a slight allowance for error on the controller side is essential to getting the shot.
- Choosing the right gear
- Setting up the camera: adding stability and balance
- Choosing the right interval for shooting
- Monitoring the shot in the field
- Developing test shots
- Putting the camera in motion
- Assembling shots in After Effects, LRTimelapse, Photomatix, and Photoshop
- Creating star trails