photography 101: depth of field


I think one of the things that makes a photograph look better than others is when the background is blurred a little. It just brings the focus to the subject and makes it look like it was taken by a professional photographer. Well… anyone can do that and here are some tips on how you can achieve a blurred background in a photo. No matter what type of camera you have. It is something called depth of field.

Last week we learned about The Rule of Thirds, this week, it’s:
Depth of Field
Depth of field is the range of distance in which objects in the photo appear in sharp focus. What determines the depth of field is the camera’s aperture. Now, understanding aperture and depth of field can get really technical… and it was very interesting to learn about it through my college class, but I won’t be so technical so that it can be easily understood, I will only skim the surface with you. On most cameras there is a setting called Aperture Priority and it appears as an “A” or “AV” on your camera dial. If you have a simple point and shoot camera and don’t have the option to switch your camera in to things like “A” “P” “Auto” “Macro,” etc., It’s okay, just stick with me here for a second.

When taking pictures in the aperture priority mode, it means that you can control the aperture, and everything else the camera will do automatically. So it’s good to have your camera in this mode when you want to control the “blur” in the background and what is in focus. I shoot in this mode about 90% of the time. You will also notice that when you are shooting in Aperture Priority, you can change a little number on your display screen. Now, this is different for all cameras, but I have a Canon and it appears in the top middle of my display screen. And it is called the F-Stop number. So there is an “F” and then a number.

This number controls how wide or narrow your aperture is. Wide aperture (smaller number)  = More blur. Narrow aperture (bigger number) = Less Blur. You can see that in the photos below. The top picture is set at a wide aperture with the F-Stop number being 2.8. Notice that only one of Elly’s shoes is in focus. In the bottom picture the camera is set at a narrow aperture with the F-Stop number being 8.0. Notice that the other shoe and some of the cement is in focus also.

So, when you want to focus on something and have the background blurry, set your aperture on a small F-stop number. If you are taking a group shot and want everything to be in focus, set your aperture on a large F-stop number. It is important to remember to change your F-Stop number because if you are taking a group shot, you don’t want just one person to be in focus and the others to be blurry.

With portraits, make sure the eyes are always in focus. It is not always necessary to keep the rest of the face in focus when taking a close up, that’s up to you, but the eyes always need to be in focus otherwise it can make the whole picture blurry since the eyes are what most people look at first in a photo.

On my camera, when I look through the viewfinder, there are little red dots that blink showing me what part of the subject is in focus. So I always make sure there is a red dot blinking on the eyes (if a portrait)  or whatever part of the picture I want to be clear and in focus.

Achieving a blurred background is easier with a special lens that has the capacity to have a really wide aperture. For example, I have one lens that gets down to F2.8 and there are lenses that go lower than that. Other lenses I have only go down to F3.8 or F4. So I can’t get as blurry a background with those lenses. It is still possible to achieve a blurry background with other point and shoot cameras, but just not as pronounced.

The blur in the pictures below was achieved from simply zooming in. You can notice how the background blurred as I zoomed in on the subject (cute little Parker for his 3rd birthday photos).

Remember these things about depth of field:

It is easier to get a blurred background if your subject is far away from the background, then as you zoom in to your subject, your background will naturally blur. So don’t stand right against the wall or a tree, stand a few feet in front of it.

The blurred effect is called Bokeh pronounced (boh-kay)

By changing the F-stop number, you are widening or narrowing the aperture, which will effect your depth of field or area in focus.


So go out and try it, put your camera on the aperture priority setting (“A” or “AV”) and play with the “F-Stop” numbers. Just put something on a desk like a pencil and practice seeing what it would look like with a bigger or smaller F-Stop number. Or hold up a flower and practice zooming in on it and seeing how the background blurs with different zooms. Keep your camera users manual handy in case you have questions. You will get used to your camera and it’s settings the more you practice.

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