Understanding ISO

     ISO is the international standard organization. Or the sensitivity to light. By changing the shutter speed you are measuring how much ISO you need, if you're in a bright lit up area it is more likely you will have a lower ISO. But if you were to be in a dark room you would want to adjust your ISO to a larger number. Now if you have a small ISO your picture will me smoother while the larger the ISO its more grainy. Aperture,ISO, shutter speed create whats called an exposure triangle. So if you were to be in a bright your room your shutter speed will be fast and ISO will be small because you want to expose not as much light as you can while in a more darker room your shutter speed is slower and your ISO is larger because you want to expose as much light as you can.

Lower ISO

Higher ISO