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Testing the Rules for Motion Blur, Shutter Speed, and Shutter Angle

Many rules in photography and videography have been constant for decades. However, some of them were formed to accommodate limitations in older technology, so are they still relevant?

In filmmaking, the 180-degree rule has been around for some time and originated from the old, spinning half circle shutter. To avoid distortion, the modern application of the rule is to — under ordinary shooting conditions — keep your camera's shutter speed at twice whatever your frame rate is set to. So, if you're shooting at 120p (120 fps), then you need to keep your shutter speed at 1/250th. This is easily followed in 24p (24 fps) and 30p (30 fps) too by using 1/50th or 1/60th respectively, or 1/60th with 24p if your camera won't allow any slower.

The waters become muddied, however, when you factor in the "look" of the video. No motion blur at all where the eye would typically see it can be jarring in the wrong scenario. Equally, motion interpolation, which aims to reduce the amount of motion blur at lower frame rates, can create the soap opera effect, which is polarizing; many like the look it creates (perhaps through familiarity), but personally, I dislike it.

In this video, Gerald Undone — with the help of others in the industry — goes about testing the different rules in videography which pertain to fps, motion blur, and shutter speed, as well as creating helpful side-by-side comparisons of different frame rates and shutter speeds to show you the real world differences.

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6 Comments

T Van's picture

This is an excellent video. One of the best discussions and illustration of frame rates I've seen.
So what is the average viewer most use to seeing in video frame rates today?
I guess in this case it may depend on where you are able to view the content.
All broadcast video is either 29.97 or 59.94.
Digital Cinema is delivered in frame rates other than 24p in some theaters.
Online video frame rates are all over the place. It's really the wild west with no rules being followed by lots of people.
Still he provides some really useful information in this video.
The example of motion blur not being affected by shutter speed and the 180 rule is pretty convincing.
I'll definitely be sharing this video.

Mark English's picture

Excellent, clear and concise explanation of an issues i understood but found difficult to explain. This video just nails it. Top marks.

Jeremy Lusk's picture

As an editor, it’s 180 degree all day if you want a natural look. Matching shutter speed and frame rate looks too blurry when slowed down, but if you speed it up to “real” speed then it looks okay, and that’s often a decent place to live if you want your footage to be useable both ways.

For sports or action, go nuts with high shutter speed. The crisp image works in those contexts and we’re somewhat used to seeing it.

Jeremy Lusk's picture

Also, when shooting 24fps, shutter speed of 50 or 60 is fine and sometime depends on the electrical standard where you live, because you may notice more flicker in uncontrolled lights if you don’t match 60hz in the USA or 50hz in Europe. That’s more important for a pro quality look (not having flickering lights) than having the perfect amount of motion blur.

T Van's picture

Did you watch the video? The visual evidence presented shows otherwise.