When shooting a time-lapse, sometimes the footage can come off jerky or jumpy – it is often referred to as the staccato effect. This is when the exposure times for each image in the time-lapse are too short to incorporate enough motion blur to allow the moving elements of the scene to smoothly transition frame to frame. Because there is little to no motion blur, these moving elements in your scene seem to jerk or jump around.
The staccato effect is not to be confused with camera shake, which is when the camera moves during your time-lapse. In order to make sure your time-lapse appears smooth, make sure there is no camera shake. Place the camera on a solid and secure tripod and avoid moving or jostling the camera while you are capturing your time-lapse. If the camera does get jostled, camera shake will require video stabilization in port production. Don’t jostle the camera and make sure it is securely mounted and this will not be an issue for you.
The first step to producing smooth time-lapse videos is to make sure that the exposure time will take into consideration the movement between each frame. You want a degree of motion blur to work as a segue from one image to the next. This can be achieved by using relatively long shutter speeds.
Although using smaller apertures is a common way to extend the exposure time for single stills, it is not the best solution for time-lapse. Depending on the lens, it may introduce flicker into your time-lapse. This should not be an issue if you are using lenses with a manual aperture ring, however, if your lens does not have a manual aperture ring, consider using ND filters. Even if you are using a manual aperture lens, ND filters are often an ideal solution to extend the exposure times. They will limit the amount of light coming through your lens, stopping the exposure down. This can allow you to have more control over the exposure times during bright time-lapse shots.
Another means by which you can extend the exposure time is to use the lower ISO numbers available on your camera. This will reduce the sensor sensitivity to light, thereby allowing longer exposures. Often you will be using low ISO numbers and applying ND filters to further extend the exposure times. Low ISO numbers also have generally higher dynamic range – if you can, find out what ISO gives your camera it’s highest dynamic range (the native ISO), and use ND filters with this ISO setting for the best results.
You may also use the aperture but beware. Between each shot, the aperture will automatically reopen to its widest to allow more light to hit the sensor or mirror to make metering and focusing more easy on the user and camera. This often results in each shot having a slight difference in aperture as the blades are opening and then re-closing for each successive exposure, and they often will not produce the exact same aperture size. This is not an issue if you are using the maximum aperture of the lens. Again, if you want to use apertures other than the maximum of the lens, this problem can be solved with a manual aperture lens. Either way, keep in mind that using very high apertures can also produce artefacts in your images. Even small pieces of dust on the lens or sensor are more visible in the higher apertures (around 18 and above), so keep that in mind.
If the time-lapse you have already shot is riddled with the staccato effect, then there are some solutions in post-production.
For starters, the simplest option would be to create your video, then open that video in a program like Adobe Premiere or Apple Final Cut Pro, and add motion blur. There are two simple ways of doing this in FCP, one would be downloading this motion blur plug-in. This will generate motion blur, however, I think it takes the dropped frames from a sped-up video and makes use of those, so I don’t know how effective it will be when you aren’t speeding the footage. However, if you did speed your time-lapse video, you could apply this effectively, I am sure. Another option is the trails effect in final cut pro. I would give these a try first, as they are simple and quick. There are similar options for Premiere. The echo effect works similarly to the trails effect in FCPX. There is also Pixel Motion Blur available for Premiere.
Yet another option will work regardless of the non-linear editor you are using, so long as it supports multiple video tracks and has the ability to manipulate opacity. The idea is to stack multiple video tracks atop one another off-set by one or more frames, with varying opacity. This will create a sort of motion blur by having the previous and following frames composited over the current frame at a lower opacity. You may also use all of these technics together – using multiple video tracks with slightly off-set timing, and including the above-described effects on some of the video channels. There is a good overview of fixing the staccato problem using the Adobe programs Premiere and AfterEffects here. A similar protocol can be followed on Apple programs as well.
Lastly, if you do end up with camera shake, Final Cut Pro and Premiere have tools to remedy these issues as well. Though there are limitations, you will find mild shake can be dealt with using the video stabilization tools in either program. Due to the stabilization filter having to change the position of the image in the video in order to stabilize it, you will likely have to crop the image somewhat after applying the stabilization. This will be true for a large number of other video editing suites in addition to FCP and Premiere.