The most commonly used film format for SLR and compact cameras is the 35 mm film. The negative picture usually has a size of 36 x 24 mm. It's loaded in a cassette and it has sprocket holes along each edge. Depending on the length of the film normally 24 or 36 pictures can be recorded.
The Advanced Photo System, shortly called APS, is a new film format. The film can be never seen by the user, because only in the camera it is drawn out of its cassette and put back automatically before removing. The negative picture has a size of 30.2 x 16.7 mm, but also panoramic pictures can be taken with the ratio of 3:1 and 3:2.
|The sensitivity of a film to light is determined by its speed. Film speed is usually measured on the ISO scale. Standard films have a speed of 100 ISO. Faster films need less light but give a grainier picture.|
|100 ISO||The standard film speed that offers a high picture quality even for big enlargements. Choose this type if you are unsure.|
|400 ISO||If the weather is expected to be rainy or you want to take pictures inside of buildings choose this film speed.|
|3200 ISO||It's the fastest film speed available. If you want to take pictures at night and don't care about grainier pictures (this can even be wanted) choose this speed.|
It is worth while to experiment with infrared films, because the shades of gray appear in a complete different way to usual film.
Infrared film is extremely sensitive to light: Better put the film into you camera in your darkroom. If you don't want to record the visible light use a very dark red filter and make a set of exposures to ensure that you get at least one good picture.