This is Part Three in the series “3 Things to Know.”
So far we’ve gone over shutter speed, or the time the shutter is open. Then we talked about aperture, how much the shutter opens. The third thing we’re talking about is ISO or how sensitive the camera sensor is to light.
ISO stands for International Organization for Standardization, but who really cares. Old film cameras used to call this ASA (American Standards Association).
The higher the ISO number the more sensitive the camera sensor is to light. So, you don’t have to keep the shutter open as long or as wide. ISO’s in most modern DSLR’s go from about 100 to 6400. 100 is the least sensitive to light and 6400 is the most sensitive.
Just like the shutter speed and aperture, this all sounds great, but of course there are problems and compromises. If the ISO is low, it’s not as sensitive to light, But – the picture looks the clearest. It has the least digital artifacts. It has less of that digital, grainy look. The colors are the clearest and the clarity of the photo is the best it can be for that camera.
The higher the ISO the grainier and more digital the photo gets. At 6400 it is all but unusable, there’s digital noise all over the place. The trick is to find the edge of where your camera’s ISO looks good and not too noisy and try not to go above that number. Also, use as low an ISO as you can and still get enough light for the photo.
So, that’s the story of light getting into your camera. ISO, shutter speed, aperture. Sensitivity, time shutter is open and amount it is open. Each adds its own aspects to the photo.