APERTURE

                                                                     ^ F2.8 aperture setting

                                                               ^ F20 Aperture setting
1. We should relate our pupils (eyes) to aperture.
2. The smaller the aperture lens, the higher the aperture number.
3. Aperture impacts depth of field because the larger the F number, the more in focus the background images get.
4. F3.5, F4.0, F4.5, F5.0, F5.6, F6.3, F7.1, F8.0, F9.0, F10, F11, F13, F14, F16, F18, F20, F22, F25, and F29.