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The main mechanism that allows film to work, is the rapid movement of several images simulating motion. These images are called the frames of a picture, and the speed at which they are replaced is measured in Frames Per Second, or FPS. This post will be discussing the history and fun facts about frames as they are used in film and animation. First we will look at why they are called frames and how the oldest models used to work.
Physical super 8 film
History:
Before our transference into the digital age, movies were recorded by flashing pictures on photosensitive paper called film (hence why we sometimes call movies film) using a high speed camera, Inside the film are small windows which are called frames which hold each individual picture. There are many debates as to the first instance of the film camera, in 1845 a light sensitive panel was drawn across an object for 24 hours to record a scientific experiment while the scientist was away, but this wasn't traditional and wouldn't be considered film.
However modern film cameras and film roles can be said to have started production in 1891 with the Kinetograph camera. Using a motor, picture frames were run in front of a projector which projected the image onto a flat surface.
In the beginning these designs we not very efficient and their bulky size meant that they had little space for the frames that ran through them and the photosensitive film could only run through the recording camera at such a speed. To save money on more expensive cameras and greater lengths of film, directors often filmed in 16-18 FPS, for perspective the minimum amount of frames necessary for the human brain to process motion is 12 FPS, although this looks like very jerky movement. To counteract this jerky movement, films were often sped up by about 14% which is why silent films look as they do.
As the years progressed and technology improved, better cameras became more widely available and film became smaller and smaller. Eventually cinematographers decided that speeding up their films was distracting, and it looked better to simply increase the frames running by the camera. And with a bit of experimentation, they settled on 24 frames per second, which has stuck to this day in most films.
This film is the first film to be shown to the general public, called Arrival of a train at the station, it supposedly made people jump out of their seats
Modern digital cameras:
In the modern day we don't have to deal with some of the issues that older cameras had. The advent of newer digital cameras invented in the 1980s meant that the mechanisms for movie creators had changed entirely. Now light is focused and reflected onto a group of sensors within the camera that take the image and turn it into a series of numbers which coordinate to a location and color. When filming, a camera will receive, process and store these numbers in rapid succession and organize them chronologically. When played back, the computer will select these individual frames and decode the storage process to show a picture. Because all of the pictures were digital, a director no longer had to be worried with the space to hold the film or the cost of buying film. However digital frames still had issues, each individual frame could constitute a large amount of information that had to be retrieved, processed and replicated in 1/24th of a second for the duration of the film. As such the pressured was now placed on the computer to take high quality pictures and display them at a reasonable speed. to counteract this two choices were made. Number 1: the FPS of a movie would still be 24fps. This speed was the standard and people were used to it at this point, additionally due to the low frame rates, certain artistic styles could be demonstrated, like the lights that fallow a fast moving car. And two the quality of the photos would be kept to a minimum, and would have to evolve with how fast computers could process. Nowadays our computers can process high quality photos with little to no issues and the first restriction is not needed anymore. However, the tradition of 24fps and the artistic compliment that comes with it keep it as the default for most big budget film.
The first digital camera compared to the more recent canon model
Animation:
Early animation such as we see in pieces like Steam Boat Willy is not what we would think of as animation currently. Instead it is much more similar to stop motion. Individual frames were drawn by hand and then photographed in sequence onto a roll of film. Because of the slow nature of hand drawing animation did not opt to change to 24fps when everyone else did, instead they continued to work at 16-18 fps. However, in 2001, Pixar in association with Disney released the first computer animated feature length film. Pixar's Toy Story used computer software to simulate bodily motion and automatically create environmental features like reflections using basic programming. And all of the frames or keyframes, as they are called in animation, were automatically made into digital data, substantially reducing the need for physical photos. Because of this, the process of creating individual frames took substantially less time and the animators of Toy Story could increase the frame rates to a more common 24fps, But it didn't stop here. As technology improved and people became more comfortable with easier softwear, the time to make frames reduced even further. And without the traditions of live action film animators decided to increase the fps of their pictures even further. Modern films like Frozen went up to 30fps and others went up to 60. these higher frame rates make the animation seem smoother and more realistic. However there is a limit, the human mind can only interpret up to 150fps and speeds past that are unnecessary. Additionally films with a higher fps still take up a lot of space and production and storage can get expensive.
Disney's animation Steamboat Willy
Stop motion:
Stop motion is the act of taking objects and positioning them manually, then taking a single picture and repeating the process until you have enough frames to create a moving picture. These frames take longer then old animation and very rarely are films made using this style. Because of the time necessary to move every object in each frame directors often use 14-18fps along side the old fashioned speed up of 14%.
The trailer for the 2009 film Coraline which was complete using a combination of special effects and stop motion
Slow motion:
Slow motion cameras are not a new invention. Although rare and expensive Slow motion cameras have existed since the early 1900s and are based on the principal of slowing down the amount of FPS so that the seconds pass by faster. However if you reduced the speed of a film running at 24 frames per second to 1/4 of its original speed, then the FPS will be cut down to 6 and the human mind wont register motion. To counteract this, specialized slow motion cameras were designed to use film faster when taking pictures, increasing the FPS. However this meant that slow motion pictures were short, usually only a couple of seconds long. In the past films were sometimes recorded at 240 fps or ten times the conventional speed so the picture can be one tenth the speed and still look natural. Now slow motion cameras can record events at up to 1 trillion fps and can reduce events to smooth motion at 1/41billionth of a second. These modern cameras can help to capture micro reactions and events in nature like the flash of lightning to aid in scientific exploration
Slow motion video of a measuring cup shattering, skip to 2:15 for the first slow motion break