Thursday, September 29, 2011
In a Different Light
Generally, the terms shallow or lack of depth are not positive. However, in the world of photography, these words take on a very different meaning.
Technically, this site started as a photoblog with each posting featuring a photo. Ironically, I have never discussed photography per se or photographic techniques here, but the understanding of depth of field is so critical in photography that I have decided to feature it in today's post.
I was in a local nightclub recently with fellow photographer Bill Shatto. The subject of depth of field came up, as it had many times before. Depth of field (DOF) is the range in distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. A shallow DOF is where the range of focus is extremely narrow - this is the technique used to create a sharp subject and blurred background. You often hear photographers using phrases such as "throwing the background out" (i.e. out of focus). The decision to use shallow DOF is quite simple - is there a subject that you want to feature/isolate, and how much do other elements of foreground or background distract or enhance the subject?
Bill specializes in macrophotography of insects, and isolation of subject is paramount to his work (which you can see here). Even different parts of an insect may be in or out of focus. But the importance of DOF extends far beyond macrophotography.
We revisited an old discussion of how nothing perhaps better distinguishes the photos of a master over that of the inexperienced photographer than the isolation of subject using shallow depth of field. This is true particularly in portraiture work. Also, one issue we both find particularly irritating is to examine our digital images and discover an object in a background ruining a photo by its unplanned and undesired prominence, like a pole appearing to come out from someone's head.
The tendency of many is either to pay no attention to depth of field or to strive for maximum sharpness throughout the scene, foreground and background. When I was younger and shot slide film with an SLR camera, I always strove for maximum sharpness over the scene. I was not aware that shallow depth of field could be desirable.
Of course, shallow depth of field is not always desirable nor possible. In the case where the subject(s) are in the same plane or at a great distance, such as a landscape, depth of field will not be relevant or impossible to control. Also, working with a narrow range of focus requires more care - it is easy to end up with elements out of focus which you want in focus. The work of master photographer Henri Cartier-Bresson shows highly successful images both with and without a shallow depth of field.
I hope that this short dissertation helps you see shallow and depth in a different light :)
NOTE: How to achieve shallow depth of field. You will need a camera that has an aperture priority mode. With this setting, you will be able to choose aperture, or size of the lens opening. The greater the opening (smaller number) the shallower the depth of field. The smaller the opening (larger number) the broader the depth of field. Many point and shoot cameras have aperture and shutter priority modes. Cellphone cameras do not and will be near impossible to control depth of field - there are some tricks and even apps for some smartphones. Note that DOF also is a function of distance to the subject and the focal length of the lens. The basics are simple, but actually this is a deep subject.
Photo Note: The lower photos shows the results of different apertures. In both images, the camera is focused on the metal cat. The left shows the result on my 50mm lens "wide open" at aperture F 1.8. The right shows the result at F 22.
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