Photography Terms Exposure
Learning Photography - All About Depth Of Field
Understanding and manipulating depth of field in an image is a key skill of professional photographers. By really understanding how depth of field works, you will have countless ways to shoot any one subject. Depth of field can seem complex and confusing, but with a little bit of practice controlling it will be almost second nature.
What is Depth of Field?
In a photograph, depth of field can be thought of as how "deep" the focus of an image goes. In more simple terms, the depth of field refers to the difference between the items in the background losing clarity compared to the subject in focus. Think of depth of field as the relationship between the focused and blurry elements of your photograph.
If you want an example of a picture with a low depth of field, imagine a picture of a flower that has the entire background blurry with the flower in focus. And on the flip side, an example of a high depth of field is a landscape photo with subjects both up close and far away clearly in focus. In either of those examples, changing the depth of field would have a dramatic impact on what the viewer experiences when looking at the final framed photograph.
What Affects Depth of Field
The primary influence on the depth of field of any particular image is the length of its exposure. The longer a digital sensor or film has to absorb the image it's being exposed to, the more detail it will accurately capture in the image. Any time you have longer exposure times, you'll always have a greater depth of field in your image.
In terms of manipulation, you can control the depth of field of any image directly by forcing the exposure time to either speed up or slow down. You can do this by changing the shutter speed of your camera; slow speeds (60 and lower) will cause longer exposures and greater depth, while fast speeds (125 and higher) will decrease exposure times and cause the opposite.
Tips for Working with Depth of Field
You can purposefully force greater depth of field into an image, however this will require manually adjusting the aperture settings of your camera. Because a longer shutter speed is required to add depth of field, less light must be allowed to enter through the lens. If you up your exposure but you don't close the aperture on your camera your photographs will be end up over-exposed.
Changing the aperture involves moving the f-stop (often the ring around the lens behind the focus ring) to whatever number lets in the best amount of light. Any new camera will let you pick a shutter speed and then will automatically adjust the f stop, but with older cameras, you'll have to play around with the light meter until the shutter speed syncs with the right aperture setting.
Helpful Tip: If you're working with high depth of field images it's likely that you'll be working with very long exposure times (depending upon the quality of your light). Taking pictures like this will usually require a tripod to prevent camera shake and image blur.
Depth of field is a powerful tool in the photographer's toolbox and should be considered in every photograph you take. All subjects or objects in a picture have a story to tell so how you decide what's in and out of focus will impact the outcome of that story. Think carefully about what you can say about your subjects with depth of field before shooting and your photos will be more powerful and more interesting as a result.
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