Aperture Priority, Depth of Field on Purpose

Aperture is the one exposure control that changes the look of a shot as much as the brightness of it. A wide-open aperture melts a background into soft color and pulls all the attention onto your subject, a narrow one holds everything in the frame in sharp focus at once. Neither is correct, they’re a choice, and right now you don’t have a feel for what your specific kit lens’s range actually does. This lesson builds that feel before you ever have to make the choice under time pressure.

Switch the mode dial to A (Canon, Nikon) or Av (older Canon naming, some others). In this mode you set the aperture and the camera handles shutter speed and, if Auto ISO is on, the ISO, to keep exposure correct on its own. This is a legitimate working mode, not a crutch, professionals use priority modes constantly when speed matters more than total manual control.

Set your kit lens to its widest aperture, the smallest f-number it supports (often f/3.5 at the wide end of the zoom, sometimes wider). Position your subject at least 6 feet from a background with real texture in it, string lights or leaves work well because blur is obvious against them. Frame the shot, confirm the meter and histogram are behaving (Lesson 1 discipline still applies even in a priority mode), and record 8 seconds.

Without moving the camera or the subject, change only the aperture to its narrowest setting, the largest f-number the lens supports at that focal length (often f/22 or f/36 on a kit lens). Record another 8 seconds of the identical framing.

Compare the two on playback. The background behind your subject should look meaningfully different, soft and unreadable in one, sharp and identifiable in the other. If they look almost the same, your background wasn’t far enough behind the subject or didn’t have enough texture to show the difference, reset and try again with more separation.