Using all three factors to control DoF
All three of the controlling factors (aperture, focal length and subject distance) can be combined to create images with extensive or limited depth of field depending upon the image you want to create.
Using a long lens, close to a subject that’s shot with a wide aperture will result in an image that has much less depth of field than one taken from a distance with a wideangle lens at a small aperture.
Swapping from a wideangle lens to a telephoto one also changes the subject size in the frame, so you may find that you want to move back a little to adjust the photo composition.
At the same aperture, the move to a longer lens reduces the DoF, but moving away from the subject extends it. The key to success is to take lots of pictures and experiment.
Film photographers have to use their camera’s depth of field preview control, which closes down the aperture so that they can look through viewfinder (which is made much darker) and see whether they are getting the depth of field that they want.
Digital photographers usually have this option as well, but it’s far easier to take an image and check the DoF on screen instead.
PAGE 1: What is depth of field?
PAGE 2: Controlling depth of field via your aperture
PAGE 3: Controlling DoF by focal length
PAGE 4: Subject distance and depth of field
PAGE 5: Using all three factors to control DoF