Film speed

The film speed refers to the sensitivity of the film to light. A film with a higher filmspeed is more sensitive to light and can be used in conditions were the photographer is forced to use a very high shutter speed or a very small aperture. The film speed is identified on the film by an ISO number. An ISO number of 800 will indicate a higher film speed than a number of 100. The film with the higher film speed can be used in darker conditions, but it will have a more "grainy" appearance. The film with the lower film speed will have a less "grainy" appearance and the photo's will be more suitable for enlargements or fine detail.

Optimum exposure

This is the setting that will allow the correct amount of light into the camera to expose the film optimally for the reigning light conditions. When changing the settings on the camera for depth of field or to "freeze" the subject, the photographer must ensure that the other relevant settings are changed to ensure optimum exposure. If optimum exposure can not be achieved at a shutter speed higher than the hand speed limit, a tripod, flash or a film with a higher film speed should be used.