The 35mm film format was developed and produced at an experimental scale in Thomas A. Edison’s laboratory by splitting 70mm roll film. Edison compiled his caveat for the double perforated cine film in the fall of 1889, describing it as a double perforated long band passing from one reel to another, driven by two sprocket wheels.
The cine film was cheap and unused short cut-off bits would certainly be available early on for use in small cameras which were easily portable in comparison the common large-format plate cameras of the time. The cine film emulsion had at first very fine grain structure and slow speed, but as the studios started filming inside faster emulsions were required on expense of the grain size, ironically making it less suitable for 35mm still cameras once they became generally available. Although the first design was patented as early as 1908, it is generally accepted that the first commercially available 35mm camera was the 1913 Tourist Multiple, for both movie and still photography, soon followed by the Simplex providing selection between full and half frame format. Oskar Barnack built his prototype Ur-Leica in 1913 and had it patented, but Ernst Leitz did not decide to produce it before in 1924.
The standard 135 format using 35mm perforated film in cassettes for the still camera has a frame size of 24×36mm – twice the cine frame size. The cassettes typically have enough film for 12, 24 or 36 frames. The 135 format became by far the most widely used photographic film format until the event of the digital camera.
The E-6 process (often abbreviated to E-6) is a chromogenic photographic process for developing Kodak Ektachrome, Fujifilm Fujichrome Velvia, Fujifilm Fujichrome Provia, InfraChrome Color Infrared and other color reversal (slide) photographic film.
Read more about E6 Film types and attributes.
CineStill 50Daylight & 800Tungsten Xpro C-41 Color Negative Film was originally movie stock or cinema film that have been prepared and packaged for use in 35mm still cameras. They have a very unique look and are meant to shoot in very different scenarios. 50D is a daylight film with very fine grain and 800T is a tungsten balanced film that performs very well in lowlight.
See CineStill 50Daylight & 800Tungsten Xpro C-41 example images and film attributes