How cinema film works: this is how films were shot before digital cameras

Before the advent of digital cameras, in the early 2000sthe was used to shoot films cinematographic filmi.e. a perforated tape on which there is a sequence of images. When you hear about “35 mm film” it is because this was the width of the most used tapes: 35 mm, in fact.

The images captured by film, called frames, were projected in succession to give a sense of movement. On the sides of the frames there are grooves, called perforationthe: These allow the film to flow through a projector or other processing machinery. The speed at which the film runs determines the framerate of the film, i.e. how many frames per second (fps) are projected. Typically films have a framerate of 24fps, i.e. 24 frames per second; usually the first films were projected at 16 or 18 fps.

To turn ten minutes of film with a professional film you need a tape the length of About 300 meters. When rolled up, the film is about the same diameter as a Pizzaand weighs one ten kilos. For this reason, a rolled portion of film is called coil or precisely, “Pizza”. So think about it whole movie how much could it weigh! For an hour and a half of filming, approximately 8 “pizzas” were needed, with a total weight ofeighty kilos!
But how is cinematographic film made to be able to capture moving images?

film reel

What is film made of? The base layer and the emulsion

Although it seems so thin, the film is actually made up of two layers, calledbasic” and “emulsion”. The base layer that’s it more resistant and its role is precisely to guarantee a solid support to the other, much more delicate layer.

Nowadays the base is made of polyester, a synthetic material. But from the 1950s to the 1990s, film made of was used cellulose acetate, an artificial fiber of plant origin. Even before that, the base was made from another artificial fiber: the cellulose nitratesupplanted because it was very dangerous and highly flammable (those of you who have seen the film New Cinema Paradisoyou know what I’m talking about).

And instead the layer of emulsion, what is it for? Here theactual image. This layer is in fact made up of gods silver saltsor chemical compounds that are immersed in a gelatinous substance.

How is the image formed?

The film is mounted inside the camera. When you open theobjective is reached by light. In jargon we say that the film is impressed. What happens is that i silver salts in the emulsion layer, they darken. This darkening corresponds exactly to the image!

negative image

In fact, the more light “hits” the silver salts, the more they they blackenproducing anegative imagewhere the light tones are reversed.
At this point, therefore, we still have two problems to resolve:

  • the film cannot yet be exposed to light, otherwise it will be “impressed” and we will have a completely dark image.
  • we have a negative image, unsuitable for projection

To overcome these two issues, the last two procedures must be addressed: development and printing.

The last two processes: development and printing

The development consists of a chemical processat the end of which the film can be exposed to light, without the grains of light darkening.
This process takes place in large machineryabout ten meters long, where the film is made to slide through tanks, where it is immersed in chemical substances for about an hourhour and a half.
Furthermore, during development, some changes can be made choices from a creative point of view: based on the time in which the film is immersed in the tanks, it is possible to intervene, for example, on the contrast.

At this point, the last step is the printing processto move from our negative image to one positive.
To do this, you use a film printer: the negative film is projected, placed in contact with a blank film. The light passes through the virgin film, creating apositive image. The positive film is in turn developed and is finally ready for projection.


All this work has been supplanted by digital devices, which made everything more agile. But the added value of a film or video remains there creativitythe historythe Images. These elements will always be subject to the sensitivity and creativity of theArt.