Motion Blur can give motion graphics and compositing projects to create a 3D configurator an aesthetically pleasing look. But what does the term actually mean and what is it used for?
If you’re a simple After Effects user, you’ve probably activated the Motion Blur switch for your compositions. It’s one of the first things that benefits your graphics in After Effects (or most other motion graphics or compositing programs), rather than just creating a title sequence in Adobe Premiere Pro or an editor of your choice.
The ability to turn on Motion Blur offers a variety of enhancements and is very easy to implement. While Motion Blur’s visual effect is pretty obvious from the start, questions remain as to what it did and why it improves the perceived look of our work.
From the perspective of motion design, it is interesting to think about how the art form began and how it has changed. In the opening sequence animated by Saul Bass, you can see that there is no motion blur.
Apart from the fact that motion design was done frame by frame with cartoon animation and a physical camera capturing each image, we now have the ability to use keyframes to create motion without ever touching a physical element by hand. As a result, we can create motion blur based on our own parameters that we set between keyframes and we can change these parameters as we like.
What led to the idea of Motion Blur? Or the need for it?
Motion Blur in terms of film and video is a consequence of the shutter angle or time.
The shutter angle is the method of measuring the time the sensor or film emulsion is exposed to the light that produces the images you see per frame. Imagine the shutter as a 360-degree circle, with the shutter angle representing a slice of pizza taken out of it. The higher the shutter angle, the longer the film/sensor is exposed to light when the shutter is rotated. Therefore, the shutter angle is the time the film/sensor “sees” the movement for the respective image. This results in motion blur.
Another way to measure the exposure time of the recording medium is called shutter speed. The difference between shutter angle and shutter time is that the latter is a measure of how long the shutter is open per second. A shutter speed of 1/48 means that the shutter is open for forty-eighth of a second. This method of measuring shutter speeds is more closely related to the world of photography, but some digital film/video cameras can also measure shutter speeds in this way.
Essentially, you could argue that this is the only reason Motion Blur exists. We are used to seeing Motion Blur on moving images. It gives everything a more natural look because we are used to seeing motion in this way through the different shutter speeds of film and video. Motion Blur is also absolutely necessary from a compositing point of view to adapt its special FX elements to its live action elements.
In early special FX examples, such as Harry Harryhausen’s work, you can see that the benefits of Motion Blur were not yet available or fully realizable. This leads to a somewhat jerky and unnatural-looking movement of these famous creatures.
Believe it or not, the human eye also has something comparable to a shutter speed. Although the human eye does not have a shutter, it has certain limitations regarding the speed at which it can resolve the light.
When it comes to shutter speed as a measurement, the human eye can detect flashes of up to 1/100th of a second relatively easily and in some special cases and lighting conditions it can become shorter than 1/200th of a second depending on ambient light and age/health.
As a result, the human eye sees Motion Blur. Of course we fight Motion Blur by focusing on individual points in quick succession, but in our periphery and if it is not fully focused, Motion Blur will be present.
Perhaps the earliest version of Motion Blur in animation and compositing was a technique known as Go-Motion.
This technique was behind stop motion animated sequences and consisted essentially of “hitting” the camera, table or model during the scenes in which the model was supposed to move. This would create the impression of motion blur. In some examples, filmmakers smeared Vaseline frame by frame on the lens in the direction of Motion Frame.
The go-motion technique is said to have been invented by Ladislas Starevich in the early 1990s. He started with the technique of pushing the set or model while taking pictures. Known as one of the godfathers of animation, he could be the inventor of Motion Blur in some ways.
Go-Motion has also been used in some much more modern applications. Phil Tippet often used this technique when working on the stop motion animation in the Star Wars series. The technique was highly acclaimed in The Empires Strikes Back’s hoth combat scene.
The above video is an example of Tippet testing the T-Rex effects at Jurassic Park, where Go-Motion created a very convincing motion blur. In the end, they came with a computer-generated T-Rex for this scene, but as you can see, Tippet was able to create a really convincing T-Rex animation with the technology.
Motion Blur in After Effects.
So that takes us where we are now. With non-linear post-production software, Motion Blur is as easy as a mouse click. We can change the shutter angle at will and we can adjust the degree of blur for each specific composition or project. If you want to add a little more naturalness to your work, Motion Blur is the way to go. But there are also times when a clean and less natural look is appropriate. So it’s good that we now have an easy way to disable/enable them.
In After Effects, you’ll find the Motion Blur settings on the composition layer in the advanced tab of your composition settings. There you can change their shutter angle and phase (a parameter that allows you to change the time for the image that the shutter “opens” – usually best left alone – to take effect).