Depth of field is a confusing topic. Most people equate depth of field (DOF) with aperture and that is one of the things that allow us to control DOF. Whether we want everything from foreground to background in focus …
AF-S 14-24mm @ 14mm 1/125 @ f13 (closed down)
or, whether we only want our subject in focus making it stand out from the background, drawing attention to our subject with no background distractions, only soft colors…
AF-S 600mm VR with TC-14EII= 840mm 1/180 @ 5.6 (wide open)
Apertures seem to be one of the most confusing areas in photography to understand and yet they play such an important role. The aperture (measured in f stops) you select, directly affects the amount of area that will be in sharp focus in our images. What is an aperture? It’s the size of the opening, designated as an f-stop, in our lens that allows light to pass through to reach the sensor. Here’s where it get’s tricky…the bigger the aperture number (f-stop)…the smaller the opening! And, the smaller the aperture number (f-stop) the bigger the opening!…
So, I hope you have this part down because I’m going to take it one step farther…and discuss how depth of field and apertures relate. Setting our lens at the smaller aperture number (f-stop 1.4, 2.8, etc), a larger opening, allowing light to enter the lens and the DOF is very shallow…
85mm 1/1000s @ f1.4
On the reverse end of the scale, if we set our lens at the larger f-stop, the smaller the opening that allows light through the lens and the result is much greater DOF (more area in focus)…
85mm 1/8s @f16
Let’s recap all of this to make sure everyone understands the aperture aspect of depth of field.
-The smaller the aperture number (f-stop) the larger the lens opening and the less depth of field or smaller numbers=less depth of field…
AF-S 600mm @ 600mm 1/180s f4
AF-S 400mm @ 400mm 1/400s @ f2.8
-The larger the aperture number (f-stop), the smaller the lens opening and the greater depth of field or, larger numbers=greater depth of field…
AF-S 14-24mm @ 14mm 1/20s @ f22
AF-S 24-70mm @ 31mm 1/8s @ f22
Over the next several weeks I will go over several other factors that have an effect on depth of field and how we can use these additional elements to understand and thus control depth of field. Stay tuned!
