What is ISO speed on a camera?
Wolf39us needs to go back to photography school. ISO (or ASA in the olden days) relates to film speed or the digital equivalent. It relates to the film or sensors sensitivity to light. A high ISO i.e. 1600 and above means that you can take pictures in a lower light without having to resort to flash. In other words the film or the sensor is more sensitive to light and needs less exposure(light) to record the image. The trade off is that the higher the film speed (ISO) the more grain or noise there will be. In everyday circumstances you should not really have to (or really want to) go above 400. However if you are doing indoor photography, sports in dull conditions, etc where you cannot or don’t want to use flash then a high speed is desireable.
