Frame rates are the number of pictures shown per second in a video. Understanding them starts with choosing which rate will be the “normal” one.

Sound movies set the frame rate standards

Silent films had vastly different frame rates. Those cameras were cranked by hand and some camera operators were faster while others cranked slower. Sometimes the camera was “overcranked” to give the film a slow-motion effect.

When the “talkies” were introduced in 1929, the frame rate had to be locked down so the audio would not be distorted. 24 frames per second was the slowest frame rate that would give good quality sound, so that became the standard for movie making.

How the human eye sees motion

Our brains take in 12–15 pictures every second and see these pictures as moving. This gives us a human picture rate of 12–15 frames per second.

Movies and videos are a bit different in how they create the illusion of motion. These methods cause confusion in the frame rate discussion. For the purposes of this explanation, frame rate refers to the number of pictures photographed for each second.

There is more info about how interlaced and progressive playback frame rates work in “Video 101: HD, Full-HD and UHD.”

Video 101: Frame Rates
Our eyes see motion as 12–15 pictures a second.


Black and white television used 30 frames per second. This had a twist to it to conserve bandwidth. The frames were split into two fields — upper and lower — so every second, two frames were seen, giving TV an effective frame rate of 60 fields per second. This was because AC power in North America is at 60Hz per second.

Color added another complication. In order for it to work, the frame rate had to be lowered by .1%. This changed the fields per second to 59.94 and set the new frame rate standard at 29.97. The standard is known as NTSC.

In Europe and pretty much the rest of the world, AC power is at 50Hz so their systems use 50 fields per second or 25 frames per second. PAL and SECAM are the names of this system.


24 frames per second (fps) is the standard speed of the camera and projector in modern movies. Some directors have experimented with higher capture and projections rates to make their movies more biometrically pleasing. If you have seen Peter Jackson’s “Hobbit,” you have watched 48 fps capture and playback as a point of interest.

Movies converted to video have the same slowdown of .1% that TV does. So 24 fps becomes 23.97 fps.

Capture frame rates

The previous section is meant to remove confusion about another pair of meanings of frame rate — time-lapse and slow motion. Once a standard capture/playback rate is chosen — 23.97 fps or 29.97 fps — varying the frame rate causes the playback to slow down or speed up. Let’s start with slow motion.

Slow motion

The faster the frame rate that’s set on the camera, the slower the playback image will be. For example, a camera frame rate of 60 fps played back at 30 fps will run twice as long as one shot at 30 fps. A 5-second scene shot at 60 fps will run 10 seconds when played back at 30 fps. The motion of the subject is slowed by one-half.

Most still cameras offer a 60 fps frame rate. Some have 120 fps. The GoPro Hero 10 action cam’s top speed is 240 fps.

Scene time, frames per second & runtime

  • A 5-second scene 30 fps plays back for 5 seconds
  • A 5-second scene at 60 fps plays back for 10 seconds
  • A 5-second scene at 120 fps plays back for 20 seconds
  • A 5-second scene at 240 fps plays back for 40 seconds

A frame rate speed that is greater than the normal playback frame rate (23.97 or 29.97fps) slows the motion. This 44-second video has two two examples — a falling magic 8 ball and traffic.

Frame rates faster than normal playback are slow motion. In this example, 54.94 fps and 119.9fps slow things down to half speed and quarter speed, respectively.


Slower frame rates speed up the scene. The slower the capture frame rate is the faster the scene shows when played back. Here’s an example. A capture frame rate of two frames per second for 10 minutes would result in a clip of 1200 frames. Playback time for the 10-minute long original would be 40 seconds (1200/60sec = 40sec). 

Time-lapse compresses time. This sample video of a section patio being filled with concrete took 45 minutes in real-time shows the process in five frames over 16 seconds. It has 488 total frames.

Video 101

Still photographers are using the video features in their cameras more and more. Like me, they probably wonder what all of the video jargon in their camera’s menus and manuals mean. Video 101 is written to help answer those questions.