8mm film format was targeted directly at amateurs and home film making enthusiasts. 8mm film was 16mm film with extra sprocket holes which were on both sides of the film. The cameraman would run the film through the camera in one direction, then reload the film in the opposite direction and expose the other half. The film laboratory would cut the film lengthwise down the center, and splice the ends together. The 25 foot film roll then becomes 50 feet in length.
In 1965, super8 film was a modification of regular 8mm film. Manufacturers were interested in retaining both the spirit and the low cost of 8mm, while improving it's quality.
While the width of the film identical, the sprocket holes were reduced in size on super 8 film. Super8 has a 25% increase in visible frame size.
Super 8mm Sound (Magnetic)
Super 8mm film was originally designed to be silent, but in 1973 the ability to record audio magnetically was born.
Super 8mm with sound came in a larger cartridge to support a larger film path, which allowed the film movement to be smoothed before reaching the recording head.
Note that only the thick audio strip opposite the sprocket holes is transferred.
16mm Non-Sound Film
Silent 16mm film was originally designed for home enthusiast. However, by the 1930's it was more popular in the educational market.
In the 1960's, the television added a greater demand for 16mm as well. 16mm was more advantageous in both cost and portability over 35mm. 16mm also provided a way to create a programming shot outside of the confines of the more rigid tv production sets.
16mm Optical Sound
The first sound film made on 16mm used an optical system. Optical uses a "wave-like" clear band which lets different levels of light to pass through. Sound is reproduced by using a exciter lamp. This lamp shines through a small lens onto the optical track. The light is focused on a solar cell on the opposite side of the film. As a "wavy" band gets wider more current can pass through the cell which causes the speaker to vibrate, producing a louder sound.
Sound quality for optical is not very good but has been improved by adding a second identical track to cancel the flaws of each track out.
16mm Magnetic Sound
As mentioned above, 16mm optical sound had flaws which caused poor audio quality. In the 1960's magnetic sound was created to resolve this issue. The benefit was that the sound was quite good compared to magnetic sound but it also had its negatives. The flaw was that many projectors were not capable of reproducing the sound.
Similar to 8mm Magnetic there was a sync issue relating to the sound and the film. News stations used a "Magnetic offset recorder" which simultaneously played the soundtrack, and re-recorded it 28 frames earlier. This allowed the film to be edited in perfect sync. Then once it was edited, it had to be run again so that it could be played back in sync on the news station.