Understanding Depth of Field

Depth Of Field

What is Depth Of Field?

 Depth of field is when a camera can only focus it's lens on a single point, but there will be an area that stretched in front of and behind this focus point that still appears sharp. It’s not a fixed distance, it changes in size and can be described as either ‘shallow’ (where only a narrow zone appears sharp) or deep (where more of the picture appears sharp).

The three main factors that will affect how to control the depth of field on the images are: aperture, distance from the subject to the camera, and focal length of the lens on your camera. 

Reference: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/optpic/1930poolballf28.jpg

Why is depth of field important?

Depth of field has an impact on both the aesthetic and technical quality of a picture. Sometimes you’ll want to use an extensive depth of field in order to keep everything sharp.

A shallow depth of field will be preferable to use as it enables you to blur the background and foreground details which causes distractions to melt away and allowing you to direct viewers to the focal point in a picture.

Aperture control depth of field

The size of the aperture controls the amount of light entering the lens. Using the aperture of the lens is the way of controlling the depth of field as you would set up your shot.

Large Aperture  = small f number = shallow (small) depth of field
Small Aperture = Large f number = deeper (large) depth of field

The above show the lower the f number, the smaller the depth of field is. The higher the f number, the larger the depth of field is.

Reference: http://media.digitalcameraworld.com/wp-content/uploads/sites/123/2013/03/Control_depth_of_field_camera_tips_DCM80.out_tech.leaf_f28.jpg

Understanding

From understanding depth of field, it is one of the important tools to use because having sharp images is one of the most important factors to getting the great shot you need. Knowing how to make the parts of my image sharp and the parts I want to be out of focus.

To use shallow depth of field, would be useful in wildlife, plants etc where you would want the subject to stand out from the surroundings. Increasing your aperture size will give you more light. Also it would be useful in sports games where I would want to separate the athlete from the background to bring attention to them. The result to this is using fast shutter speed.

Reference: http://www.wall321.com/thumbnails/detail/20140221/nature%20birds%20depth%20of%20field_www.wall321.com_64.jpg

You would use deeper depth of field when you want to get a landscape image as it is important to get as much of your scene in focus as possible. By using a wide angle lens and a small aperture I will be able to maximize my depth of field to get the scene in focus.

Reference: http://images.macworld.com/images/howto/graphics/150150-dof-blong-figure-3_original.jpg

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