SUPER-8: -12, THE CURSED FRAME.

There is, when shooting in Super-8 proper (using the cartridge designed by Kodak), a cursed frame: -12, that is, the one located 12 before the exposure window, just where the convoluted coaxial design forces the film to wrap around itself, to go from one axis to the other.

If the Super-8 cartridge is left in the camera with the filming interrupted for a while, the triacetate film base takes shape on that spindle (a problem that is accentuated as the hours go by or under certain conditions of temperature and humidity): as the Super-8 lacks of pressure pad  in camera, this frame -12 will almost always be blurred, out-of-focus and, some times, with certain cameras,  will even produce some instability in the images immediately before or after (jittering that, although can be stabilized in post-production, is, however, visible in direct projection of the reversal original).

The lack of proper pressure plate in camera makes impossible to keep the film perfectly flat: with the Super-8 cartridge the film flies through an air-channel, friction-less; the plate of the cartridge locks onto the knobs on the camera gate assembly, which means the film is not very tight in a fixed position (hence it is nonsens to collimate lenses to the nanometre, when you cannot tell where the film will be!). Notes: a) only Nikon R models have a special pin wich forces the film into a more strictly defined position; 2) None of this applies to Single-8 or Double Super-8, as both gauges has a proper pressure pad in camera. 

This problem at frame -12 is accentuated the more fat the triacetate base is.

Not many are aware that when the Super-8 was developed, its film base was planned to be made of polyester, much more flexible and therefore immune to this trouble. The problem is that when, at the time of going into production, Super-8 passed from the engineers to the accountants, due to the higher cost of polyester, Kodak continued to make it in the cheaper cellulose triacetate.

Only Fujifilm, in 1965, presented its 8 mm type S films in polyester, and, moreover, in a better designed cartridge (called Single-8), with a more direct path in parallel axes (which allow integral rewinding) and with space for the camera to have a proper metallic presser pad for the film (as in Double Super-8). Film, with Single-8 cartridges, is 8 mm type S, the correct name for Super-8 (8 mm wide but with type S perforation).

Single-8 cartridges were designed to be opened and reloaded, making them very environmentally friendly (video by Luigi Petrin).