Depth of Field - a Major Player in Creative Control

When people talk about Depth of Field (also called DOF), they usually start talking about f-stops. These are numbers like f-1.4 or f-32 that represent how much light the aperture lets into the camera. While this is important, this is not where I want to start today.

There are three basic things that affect Depth of Field and they are:
1) the lens aperture (f-stops)
2) the lens focal length (the size like: 35mm vs. 200mm)
3) the subject distance (how far it is from the camera)

Keep in mind that most digital cameras do not have f-stops as per say. In fact if you have a straight point and shoot camera with a set lens, it may feel like you have no control at all.

Both the point and shoot and even many of the more advance digital cameras are based on a false premise. They assume all people want their photo in focus, all the time. “Now wait a minute”, you say. “I want my pictures in focus . . . don’t I?”

Remember, we are not talking about a 110 year old lady who can not hold the camera steady. A photo tip many people don’t realize is depending on where you focus in any given photo; so much in front of the subject and so much behind the subject will also be in focus. Generally, more will be in focus behind the subject than in front of it. So if you want a really sharp photo try focusing 1/3rd of the way into the image, not dead center.

There are good reasons for wanting a narrow DOF verses a wide DOF. Wide DOF means everything in focus all the time. For those who are not “into” photography this mode is good 90% of the time. Here are some examples of when you may NOT want to shoot that way.

A) Portraits: focus on the person and blur the background. This is helpful when there are distracting elements behind the subject.

B) At the zoo: focus on just the animal. The idea here is to make your photo look like you took this animal in its own natural environment.

C) Flower shots: focus on part of a flower, and let the others flowers around it become a painted background for your image.

D) Sporting Events: focus in on the one who crossed the line first, jumped the highest, or ran the fastest. You can show the winner better by using creative DOF.

So, how exactly do we control Depth of Field? Shooting an object that is 5 feet from the camera will have a narrow DOF range verses shooting the same object from 25 feet away. Keep in mind that the closer you are, the fewer things there are that can distract your viewer from what you really want to show.

Most set lens range from 28mm – 38mm, there is less to adjust, less to think about, and unfortunately less control. Another photo tip is this; if you photograph someone using the 35mm end of the scale, more of the photo will seem in focus (wider DOF.) However . . . if you have a zoom lens and shoot with the 200mm end, much less of the photo will seem in focus, because you are using a narrower DOF. This is selective DOF, and it has nothing to do with the f-stops.

If you do close-up photography the close-focus or macro mode of your camera will also give you a fairly narrow depth of field. But you can push that even further by using filters. Most cameras, will now accept filters. But even if yours does not (set lens again); you can hold the filter in place and still shoot. Close up filters allow you to shoot much closer than the lens will by itself, and in most cases it also gives a very narrow DOF.

Many of today’s cameras have more than one auto mode. In a fully automatic camera you have not gained much if any control, but if you have the option for Aperture priority or Shutter Priority you are back in the driver’s seat. Basically put: Aperture Priority means that you control the aperture (or f-stop) and the camera picks the right shutter speed to get a proper exposure. Conversely, Shutter Priority does the exact opposite, you control the speed and it will pick the correct aperture for the given light conditions.

Since I brought it up, I guess now would be a good time to explain f-stops. The words aperture and f-stop usually refer to the same thing. I have absolutely no idea why we don’t call them “a-stops”, but just so I don’t confuse anybody, I will call them f-stops. The f-stop controls how much light enters the camera. Many books and magazines confuse people by referring to how big the opening is and how small the depth of field is. Most people don’t care about the mechanics of the process they just want to understand the end result.

A small number (like f-1.4) means only a small amount will be in sharp focus.
A large number (like f-32) means a large amount will be in sharp focus.

But wait, you’re saying to yourself, “I don’t even have an aperture mode.” Maybe you do, and don’t realize it. If you’re camera has little pictures or icons on it, like many cameras do, you may have more control than you realized. The picture of the small head means portrait mode. (Your girlfriends smile will be in sharp focus but not the tree behind her.) The picture of the little mountain means landscape mode. (Her smile will still be in sharp focus, but so will the tree 20 feet behind her.)

Most people are attracted to the thing that is in the sharpest focus, so, it becomes very hard (visually) to be attracted if the entire photo is in complete focus. There is nothing specific to draw the viewers’ attention. By using the creative possibilities of depth of field; no matter what kind of camera you have, your images will be much more powerful and interesting.