Understanding depth of field in photography can be a bit confusing at first, but it really is a simple concept. By better understanding depth of field and how to use it in your photos, your photography skills will greatly improve.
Depth of field is produced by three related factors:
- Lens aperture
- Focal length
- Distance from the camera to the subject
By properly controlling these three variables, depth of field can be controlled to make a better photograph.
What is depth of field?
Depth of field refers to the fact that as you adjust the lens of the camera to focus on the subject, it will get perfect focus only at one specific distance. Anything that is in front or behind that focus point will be out of focus to some degree.
Depending upon the effect desired in the photo, depth of field can be controlled. The first way is with aperture.
The aperture determines the diameter of the light that enters the lens. The wider your aperture, the wider the light beam. A wider beam of light is going to have more effects from depth of field than a narrow beam.
So, using a wider aperture gives a shallower depth of field, and a narrower aperture provides more depth of field.
Focal length is the measurement of how much a particular lens magnifies the photograph. The lens will magnify differences in focus as well. Generally, a longer focal length will magnify focus differences, and there will be then a shallower depth of field.
The closer your subject is to your camera, the more the relative distance from the front to the back of the subject. A higher distance will provide a reduction in how much of that subject is in focus.
How to Control Depth of Field
Depending upon the photo, you may want to have more or less depth of field. If, for example, you are shooting a friend in front of a beautiful waterfall, you may want a deeper depth of field so that both the friend and the waterfall are in focus.
Or, if your photograph’s focus is simply on your friend and not the background, you may want a shallower depth of field. This will keep your friend in focus, and the background blurry.
So to sum up, to increase the depth of field, use:
- Narrower aperture
- Shorter focal length
- Move away from the subject
To decrease depth of field: use:
- Wider aperture
- Longer focal length
- Move closer to subject
Now that you better understand depth of field, use that knowledge in your photographs. Good luck!