APERTURE

1. we should relate the Iris to the aperture on the camera.
2. the smaller the aperture, the more light that is let into the camera. the larger the aperture, the less light that is let into the camera.
3. aperture impacts depth of field because if you have a smaller aperture, the background will be in focus like the foreground, but if you had a larger aperture, the foreground would be much more clear than the background.

this picture was taken at a f/16 aperture

this picture was taken at a f/2.8 aperture