The ISO is the last of the 3 settings which help determine the exposure. So far we have spoken about the shutter speed and the aperture, the ISO helps adjust these settings. The ISO is the sensitivity of the sensor and is measured in numbers. For example 100, 200, 400, 800, 1600, 3200 and 6400 are avaliable on my Nikon DSLR. The ISO may need to be raised if a shutter speed isn’t fast enough because of lack of light. By increasing the ISO the amount of available light is picked up more by the sensor allowing a usable shutter speed to be used.
There is one issue with increasing the ISO is noise. As the sensor becomes more sensitive to light, digital noise can be found on an image. Modern DSLR’s now have some great noise reduction capabilities which make high ISOs usable. Noise can also be removed by some photo editing software.
So thats it for the ISO , come back next week for an article on white balance.