Depth of Field in Photography

Depth of field is how much of your image is in acceptable focus. A large or deep depth of field means that a lot of your image, beyond the point of focus, is in focus. A small or shallow depth of field means that very little of your image, apart from your point of focus, is in focus.

Depth of field is controlled by three things: aperture, subject distance from the camera and focal length.

Aperture and Depth of Field

Aperture is the first factor that affects depth of field, and is the one that many people are already aware of. Larger physical apertures, or smaller f-stop values, gives you smaller, or shallower depth of field. A smaller physical aperture, or larger f-stop value, will give you a larger or deeper depth of field. This means that a large portion beyond your focus area will be in acceptable focus.

Subject Distance and Depth of Field

Subject distance from the camera is the second factor that affects depth of field. The closer your subject is to yore camera, the shallower your depth of field will be (assuming that your focal length and aperture stay constant). This is because the planes of focus get thinner as you get closes to the camera. When your subject is further ways from your camera, it's harder to get shallow depth of field.

Focal Length and Depth of Field

Focal length is the final factor that affects your depth of field. Wider focal lengths give you less depth of field at equivalent aperture and subject distance than a long lens would. Longer lenses compress your scene and push your background further back.

Depth of Field and Bokeh

I often head Depth of Field and Bokeh being used interchangeable, which shouldn't be the case. Depth of field is the amount of image beyond your focus point that is in focus. Bokeh is a Japanese word that literally translates to "blur". Bokeh refers to the actually out of focus area of your image, not what is in focus.


Back to Digital Photography 101 Index