Posts Tagged ‘Focal length’

There’s a direct relationship to how much depth of field is created in a photo to the focal length of the lens, the aperture at which the photo is made, how close the subject is to the background, how far away the subject is from the camera, and how much the subject is magnified.

Focal Length – the more telephoto the lens, the less potential for near to far depth of field. The wider the lens, the greater the potential. For instance, an image made with a 28mm lens will inherently display more depth of field than a 100mm lens. So if you want to create shallow depth of field and you’re using a wide lens, it may not be possible. If you’re using a telephoto lens and you want to a subject close to the lens and a distant object to both be in focus, it may not be possible.

The Aperture – the wider open the lens, the less depth of field. The more it’s stopped down, the greater the depth of field. In other words, f4 will net shallower depth of field than f22 based on a given focal length. It’s important to realize the connection to focal length as explained above. If you’re using a telephoto lens, even though you set it to f22, you still may not be able to achieve near/far depth of field. Understanding how focal length and aperture go hand in hand is key!

Proximity to the Background – The farther away the subject is from the background, the more the background can be thrown out of focus. If the subject is very close to the background, it’s not possible to make the background go very soft even if you use a super telephoto lens and set the aperture to f4.

Distance From The Camera – If the subject is very close to the camera and the focus point is placed on the subject, there’s more potential to create shallow depth of field than if the subject is 25 or more feet away. Again, there’s a relationship to the focal length of the lens, the aperture at which it’s set and how far the background is from the subject.

Subject Magnification – The more macro the subject, the less depth of field. This area of depth of field is more specialized and it really is a subject unto itself but I just wanted to bring it up to let you know it’s a variable.

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