Depth of Field

The depth of field is basically how far into the picture you can see and have it still be in focus.  This is changed by the aperture (or f-stop).  Depending on the camera and its age, it may be called either one.  This is the small ring around your lens with the numbers ranging anywhere from 1.2-16 or so.  Most automatic cameras and/or digital cameras control this function through the camera, so that little ring doesn't need to be turned.  When we are taking photos and trying to make a certain part the "Focal Point" of the photo, we need to make sure that part is in focus of course, but we also need to make sure the rest of the photo doesn't distract from that Focal Point.  This can be done in many ways, but depth of field (DOF) is usually the easiest way to do this.  This can take some work and some adjusting.  To attain this shallow depth of field the camera needs to be set at a low aperture/f-stop.  Those numbers correlate to the amount of light coming into the camera.

Remember when setting your camera:

Low F-Stop = Large Aperture = More light = Shallow DOF

High F-Stop = Small Aperture = Less Light = More DOF

My high school photography teacher explained it in a way that, it must be said, made him look like a crazy person, but it is completely accurate and easier to understand, so I'm going to try to show you.  This works especially well if you wear glasses and you take them off.

First, open your eye like this and try to fous on something.  Once you have found something that you can focus on (you can hold it close to your face if you need to)  look around and see what you can see.  This is an example of a "wide open" aperture.  This will be a large aperture and small f-stop (small number).  You can focus on one thing, but the rest of the room will be more difficult to see.

Second, relax your eye and just look around.  Focus on the same object and look around the rest of the room.  You should be able to focus on more things, but still not be able to see everything.  This is a medium aperture opening.

Finally, squint your eyes so you are looking through your lashes.  Your eyes should be very nearly closed.  If you look around the room you should be able to see most of it.  At the very least (if your eyesight isn't that good) you should be able to see more than you could with the other two.  This is a very small aperture, which would be a large f-stop (large number).

In the following images, we have very "shallow" depth of field.  This means that the plane of the photo that includes the main subject is in focus but everything that would be in front of it or behind it would not be in focus.