Depth of Field

Depth of Field
Let us try to fully understand Depth of Field, in digital photography it is one of the most important aspect to consider since we already understand the exposure.

What is Depth of Field?

The depth of field (DOF) is the portion of a scene that appears sharp in the image. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on either side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.

Depth of field (DOF) is the distance wherein objects are in focus.

This is the pragmatic explanation.

To be technically correct, DOF is the zone of acceptable sharpness, the area in front of, and behind, a focused subject that appears in focus.

Circle of Confusion (COF)

Technically, only the subject in focus -- and all other objects at the same distance -- are in focus; everything else in front and behind are out of focus. How much out of focus depends on a term called the "Circle of Confusion (COF, or COC)."

What Affects DOF

What we really want to know as photographers is what affects DOF so we can control DOF in our pictures. For a long, long time, photographers have gone with the following three criteria in digital photography:

• lens aperture
• distance from subject
• focal length

While the first two are technically correct, the third one has raised somewhat of a storm of controversy among certain circles. Why exactly, we will make clear later. Let's look at each of the three criteria in more detail.

A short depth of field can be very useful when you want to isolate your object from the background, such as when taking portraits or macro photography. A large depth of field is great when you photograph landscapes and overall when you want every detail to be in focus.

Control the Depth of Field

There are three variables that affect DOF in digital photography, the size of the Aperture, the distance to the object and what lens you’re using. (There is a fourth thing that affects the DOF, but that’s the size of the sensor and unless you have two cameras with different sensor sizes this isn’t something to take into account.)