One of the biggest advantages of digital cameras or DSLR’s over their film counterparts is the ability to switch ISO settings on the fly. ISO is the amount of light that you let into the camera’s sensor and in the days of film cameras this was accomplished with film speed, sometimes called ASA instead of ISO. So if you wanted to shoot outdoors, you would load a roll of ISO or ASA 100 or 200 and be good to go, but if you then moved into a dimly lit building and wanted to shoot, you needed either a flash on …