Film Facts

35mm film travels at 90 feet per minute, 24 frames (still pictures) per second (fps)
or, if you prefer, 1.5 ft  per second
Each foot of film consists of 16 frames
Just over 1.022 miles of film is projected per hour

This means that 1440 frames  are shown every minute, or 86400 frames per hour

The period of time required to move one frame away from the aperture, and bring the next frame in is
1/96 second

During this period of movement the light  from the arc is cut off by use of a revolving shutter
If the light was not cut of during this movement  then you would observe streaking (ghosting) on the screen caused
by the pull down movement being projected

The film is then stationary, and the light is allowed to shine through the film, and project onto
the screen

 During this stationary time the light is again cut off for another 1/96th second by a second blade
on the shutter

This uprates the flicker from 24 to 48 times a second (hertz)

The reason that the light is cut off twice is that if it was only cut 24 times per second there
would be noticeable flicker on the screen

By cutting it off 48 times this flicker is not noticed, except on very, very bright scenes

This is why the shutter is often called 'The Flicker Shutter'

The film frame is actually only projected onto the screen for 1/32nd of a second
For a more detailed explanation please click HERE
Return To Flicker Shutter Photograph
16mm sound film runs at 24 fps, a speed of 36feet per minute, or  40 frames per foot

To find running time of 16mm film divide the film length in feet by 36
This will give the minutes as a whole number and a decimal
Make a note of the whole number, and multiply the decimal by 60 to get seconds
Add this total to the whole number

For example
The running time for 374ft of 16mm
374 divide by 36 = 10.388
0.388 X 60 = 2328
Running time = 10mins 23secs

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