Depth of Field is the zone of sharp focus, in other words, how much of an image is in focus. 

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• A Deep Depth of Field means that most or all of the image is in sharp focus (big f-stop#)

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• A Shallow Depth of Field means that a small portion of the image is in focus (small f-stop#)

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How does DEPTH OF FIELD work?

If you are photographing a landscape scene, you will likely want all of that scene to be in sharp focus, a deep depth of field so you audience see everything in front of them. You will need effective use of lines and perspective to help tell the story of give the impression you want your viewers to feel. A shallow depth of field in a landscape image might be confusing to your viewers

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At other times you will want only a small portion of your overall image to be in focus. For example, in a close up macro shot of a flower, you will want the flower to be in focus and everything else to be softly out of focus, a shallow depth of field.

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The out of focus part of the image is called the "bokeh"

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You have seen images where the one part of the flower is in super sharp focus and the rest is soft and blurry. Some portrait shots also look like this, using a shallow depth of field on purpose…the person is in sharp focus and the background is out of focus.

Why would you want to do that?

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1. It brings a stronger emphasis on your subject with it being the thing most in focus in your image

2. The biggest reason is that your eye will naturally go to whatever is in focus in a photograph.

3. So, if you are shooting a wedding and you have a photo of the bride and groom, but they are out of focus and the people behind them are in focus, your picture will be ruined because your audience will look at the people behind the bride and groom, instead of looking at the bride and groom.

4. We assume that if something is out of focus, that we aren’t supposed to look at it.

5. So you can use shallow depth of field to force your viewer to look at your subject.

6. Make sure that whatever your subject is (flower, rock, insect, bride etc) that it is sharp and in focus. If the rest of the image is out of focus, that part of the image will stand out and people will immediately look there

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Selective Focus—you chose what parts of your image are in crisp sharp focus and which parts are in soft focus (blurred)…this brings the attention of your audience to the parts of your picture that you want them to really notice.

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As a photographer you have the ability to determine what you want people to look at. By using a shallow depth of field & having only part of the scene in focus, you will make sure that there is no doubt about what the subject is and where you want your viewers to look.

A deep depth of field is used to show grand scenes in nature when you want to overwhelm you audience with beauty, but everything in focus must work together or the subject of your picture could get lost.

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With lots of practice and seeing the results, depth of field will be come an invaluable compositional tool.

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Depth of field is achieved by two controlling factors:

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1. The size of your camera’s aperture…the f/stop number setting controls the camera’s aperture. The focal length of your lens controls the actual size of the opening in millimeters. The size of the aperture is found by dividing the f/stop number into the focal length you are using to shoot with.

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2. The distance of your subject from other parts of your image such as the foreground or background. The more separation of your subject from other parts of your frame, the lesser the depth of field will be when focused on your subject

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Depth of Field—the total amount of an image composition that is in clear focus

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The larger the aperture (opening), the smaller the f-stop number, and a limited or shallow depth of field will be achieved in the image…an f-stop of f/1.8 will have less things in focus than an f-stop of f/11…when zoomed in or shooting portraits of people and flowers, usually less depth of field is desirable to put all of the emphasis on your subject by keeping the subject in full focus while blurring everything else, which is the technique for creating a nicer portrait

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The smaller the aperture (opening), the larger the f-stop number, and a greater or deeper depth of field that will be achieved in the image…an f-stop of f/22 will have almost everything in an image in focus, whereas a f-stop of f/2.8 will have at least half of the image out of focus…when shooting landscapes/scenery, usually a maximum in depth of field is desirable to keep everything from the foreground to objects in the far distance in clear focus.

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Zooming in on a subject creates less depth of field because the aperture gets bigger as the focal length gets longer when zooming in…Zooming in from 50mm to 300mm will create a larger aperture and thus permit much less depth of field (in this case 6 times less), so the subject will be in clear focus, but everything else in the composition will be blurred. The blurred parts of the image: Bokeh (pronounced “bow-keh”)

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The bigger the millimeter (mm) number of a lens, the bigger the zoom and the closer the lens can get to a subject…but the focus of the lens is very narrow or shallow...300mm is zoomed in 3x of 100mm and thus has three times less scenery in frame…

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The smaller the millimeter (mm) of a lens, the “wider the angle” of a lens or the more scenery that can be captured into focus in a single frame of a composition--the focus is greater or deeper. A 15mm lens will allow a photog to capture 10X more scenery than a 150mm lens…

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