Sensitivity (ISO or ASA)
This setting determines how sensitive the sensor, or film, is to light. On a sunny day outside an ISO (ASA for film – the same thing essentially) setting of 100-250 ISO should be fine. On a cloudy or murky day, 400-800 ISO would be more suitable, while indoors at a show, 1600 ISO or higher will be the only way to get a good shot. The higher the sensitivity, the darker you can shoot in, but the quality of the image will suffer with noise, or grain on film, making the image look ‘gritty’.