The Film

Film is the light-sensitve media on which captured images are stored. Image information is stored as “latent” images which must be processed in order to be made visible.

Film comes in many different formats, that is sizes and aspect ratios. The most common format of film is 135 or simply 35mm, whose dimensions are 36mm x 24mm. It is said to have a 3:2 aspect ratio; that is its height is two-thirds of its width (or, its width is three-halfs of its height). The second most common type of film is 120 which can have several formats, the most common of which is 6cm x 6cm, a square format with an aspect ratio of 1:1. Square formats have the advantage of not requiring any rotation of the camera. Other 120 formats are 7cm x 6cm, and 6cm x 4.5cm and 9cm x 6 cm. There are many other film formats as well.

Film formats are divided into three classes based of film size; Small format (135), Medium (120, 220), and large (4x5, 5x7, 8x10). There can be many “formats” in terms of aspect ratio within a give film size.

Film is supplied in light-tight cartridges (110, APS and 135), rolls (120), or sheets (4x5, 5x7, 8x10).

Film comes in many different emulsions with different color, saturation, contrast and grain characteristics. The most common emulsion produces a negative image which becomes a master for producing prints. The next most common emulsion produces a positive image which can be viewed directly or projected, as well as being printed through a more complicated process. Most emulsions are balanced for daylight, although some are available for tungsten.

Film comes in many different sensitivities or “speeds” ranging from ISO 3200 (fast, coarse grain) to ISO 25 (slow, fine grain), the most common being ISO 200. The acronym ISO is used to denote film speed, but it is actually the logotype designation for the International Organization for Standardization. Prior to ISO, ASA/DIN was used, the acronym for American Standards Association and German Institute for Standardization (Deutsches Institut für Normung). Most cameras have an ISO setting to tell the metering system which speed of film you’re using. You can set it to match the speed of the film, or set it one to two stops higher to “push” the film, or one to two stops lower to “pull” the film. If you do this, you must process the film at the ISO the camera was set to in order to compensate. Some films respond to this technique better than others.

Which film speed you use depends on the lens speed, aperture range, shutter speed range, and lighting conditions. Fast speed film is used in conjunction with faster shutter speeds to capture action, or subjects in low light. Slow film is used in conjunction with slower shutter speed to increase resolution in still subjects, or in bright light.

Formats at a glance:
(Dimensions are width x height in the natural orientation of the camera)

110 
110, 17mm x 13mm, 4:3 aspect ratio, landscape orientation

APS

APS-C (Classic), 25.1mm x 16.7mm, 3:2 aspect ratio, landscape orientation

APS-H (High Definition), 30.2mm x 16.7mm, 16:9 aspect ratio, landscape orientation

APS-P (Panoramic) 30.2mm x 9.5mm, 3:1 aspect ratio, landscape orientation

135

full-frame, 36mm x 24mm, 3:2 aspect ratio, landscape orientation
half-frame, 18mm x 24mm, 3:4 aspect ratio, portrait orientation
square, 24mm x 24mm, 1:1 aspect ratio, universal orientation
sprocket hole, dimensions, aspect ratio and orientation governed by camera’s mask.

120, 220
6x6 (square, 2-1/4"), 6cm x 6cm, 1:1 aspect ratio, universal orientation
6x7, 7cm x 6 cm, 7:6 aspect ratio, landscape orientation
6x4.5, 4.5cm x 6cm, 6:4.5 aspect ratio, portrait orientation
6x9, 9cm x 6cm, 3:2 aspect ration, landscape orientation

Sheet Film
4x5, 12.7cm x 10.2cm, 5:4 aspect ratio, portrait or landscape orientation
5x7, 17.8cm x 12.7cm, 7:5 aspect ratio, portrait or landscape orientation
8x10, 25.4cm x 20.3cm, 5:4 aspect ratio, portrait or landscape orientation