film speed information

Film speeds often seem confusing at first, but can be easily explained. Film speeds usually come in variables of 100 and have the suffix ASA. Professionals sometimes use film speeds that range in quantities of 25.

100 ASA is one of the most common film speeds. What this means is that the amount of light-sensitive crystals impacted on the gelatin of the film will react to normal light at a certain sensitivity and time. A film speed with an ASA of 200 will only need half the amount of time for a correct exposure than the 100 ASA. 400 will, in turn, need only half the time of the 200 ASA film type and is commonly used for night photography.

Other speeds for very low-light situations include 800 and 1200 ASA. With these types of film speeds, the film is so sensitive that you could actually point and shoot without a tripod to take a picture at night.