It is useful to do your own depth of field comparison using consistent distances between your camera, subject and background. Of course aperture (f-stop), focal length and sensor size all play into how much depth of field you will achieve.
In the photo of the maple leaf below, you can see the background is fairly well out of focus.
Despite using a very small aperture of f-13, the background is somewhat blurred. The subject is so close to the camera that sharp focus falls off quickly even though the background was only a few feet away.
Look closely at all three leaf photos to really notice the subtle differences in this comparison of depth of field, which I based solely on changing the aperture. Changing the aperture is the most often discussed factor when photographers try to control the depth of field because it is often the simplest to change.
The diagram below (4) shows the close camera-to-subject and subject-to-background distances which are big factors in determining how much depth of field will result.
If both the subject and background were more distant from the camera, as is shown in diagram 3, an aperture of f-13 would render both the subject and the background in sharp focus.
Often you get a more pleasing photograph with a blurry background or narrow depth of field because you have created more visual separation between subject and background.
At f-4 you can see the the background is significantly out of focus as well as parts of the main subject, my brightly colored maple leaf. Taking the photo with a full-sized-sensor, Canon 5d Mark III, using a telephoto setting of 105mm at f-4, and having a close subject distance all are contributing factors that give us a shallow depth of field
In the scenario diagrammed below(2), you would need to use a tiny aperture, have a very small camera sensor like those in a cell phone camera, or have a very wide-angle lens setting to get both subject and background in focus at the same time.
If this depth of field comparison is all a bit too new for you, I suggest you read the page again and try to grasp the concepts presented. As I have said, I am not a professional writer and am better at communicating through my photography than I am at expressing myself through the written word.
Search for a different article on this site:
Looking for more articles on Depth of filed. use this search box and be specific with your search words.
Back to Examples of Depth of Field
Have a blast with your digital photography!