Creating the Illusion of Speed
By Kavon Zamanian (edited)
Making action appear faster than it is, or even simply as fast as it is actually occuring, is a bit more complex than one might think. Visible speed depends on a variety of factors, ranging from camera settings to framing. In most cases, you can’t shoot a real car chase at breakneck speeds, so let’s take a look into some of the Hollywood trickery involved in high-speed action.
We’ll start with the basics. Motion blur is one of the most important things to consider when exaggerating motion. It is generally the result of an object moving very fast or slow in comparison to the camera. The larger the difference in speed between an object and the camera filming it, the more motion blur that object will create.
In most cases, motion blur is best applied to background objects, rather than the subject of the shot. For instance, motion blur is great for tracking shots in which the camera is traveling a similar speed to the subject. However, you would want minimal motion blur when your subject is quickly flying by the camera.
The viewer’s focus should never be on a blurry object or person, so be sure to limit its use to unimportant, passing objects, unless there is a specific exception in which you want to draw attention to the blur.
Technically speaking, high motion blur is achieved with a low shutter speed, and vice versa. For example, if shooting at 24 fps, a shutter speed of 1/50 would produce motion blur, whereas a shutter speed of 1/2000 would virtually eliminate it. Be sure to always set your shutter speed to at least twice your framerate (For 24fps, set to 1/48. For 60fps, set to 1/120), as anything higher will result in choppy, unnatural-looking footage.
Incorrect use of motion blur
Correct use of motion blur
The iconic speeder bike chase of Star Wars Episode VI: The Return of the Jedi is a classic example of effective application of motion blur. Interestingly enough, this sequence was shot by walking through the forest and shooting one frame at a time, then superimposing the speeder bikes over the resulting footage. Because photos aren’t restricted by a frame rate, they can use very low shutter speeds to increase motion blur beyond the limitations of reality, which was great for depicting the blisteringly high speeds of the futuristic speeder bikes.
The way a moving object is framed can drastically affect how fast it appears. When shooting a moving object, especially from the side, tighter shots such as a medium shot or close up will emphasize speed. This is because usually objects appear faster when close, and slower when far away. This optical illusion is the reason that passing airplanes tend to appear very slow despite moving very quickly. Read more...