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Veteran photographers will often tell you that the chief difference between the camera and the eye is focus -- your eye has a nearly unlimited depth of field, but a camera lens does not. This affects photography in the number of ways since it makes it largely impossible to truly capture what the eye sees.
Some photographers have fought to overcome the limitations of the camera lens depth of field. Seminal photographers Minor White and Ansel Addam's even formed the "f/64 club," which took its name from the smallest lens aperture (which yields the greatest depth of field) and sought to produce images that matched what the human eye might see (at least when it comes to depth of field).
Others have chosen to embrace the limitations of the lens and in doing so gave birth to a type of photography known as "Boke" (sometimes spelled Bokeh). Boke is a Japanese term that translates to roughly "become blurred or fuzzy" and is used to describe images that have a sharply focused subject surrounded by a blurry background.
Whether you're looking to break out of a photo rut or just interested learning something new, read on and we'll show you how to create a Boke effect using your camera, and how to fake Boke in your favorite image editing software.
A technical explanation of what causes lens blur is beyond the scope of this how to, but if you're interested in the why and not just the how, we recommend reading through [http://www.luminous-landscape.com/essays/bokeh.shtml Luminous Landscape's essay] on the subject.
== Using the Camera ==
The "true" way to achieve selective focus is to use the manual settings of your camera and allow the lens to be its imperfect self.
So how do you do it?
Well, the best place to start is with a very large aperture opening which will decrease the depth of field, in turn creating the out-of-focus background effect associated with boke. In terms of settings that would mean the lowest f-stop -- depending on your lens or camera that could be anywhere from f/1.4 to f/4.9. The lower the number the wider the aperture opening and the less depth of field.
But blur isn't solely a result of aperture, it is also influenced by the distance in front and back of the focus plane. The focus plan refers to that portion of an image which is perfectly in focus.
Let's say you're standing three feet from your friend and you focus on their face. Behind them is a barn, over twenty feet away. Using a large aperture opening will limit the focus plane to your friend's face while the barn blurs in the background.
Here's the same effect, the focal plane is on the dandelions will the grass in the background is blurred:
truelensblur.jpg
The trick to getting a good boke image is knowing how to compose the image and what aperture to use. The best way to learn is to experiment, especially since the results will vary radically from camera to camera and even lens to lens.
== Using Software ==
Didn't get the boke effect quite the way you wanted using just the camera? That's okay, we can simulate the effect in Adobe Photoshop, but of course you can do something similar using the GIMP or almost any other image editor that has a blur tool.
There are a number of ways to fake depth of field in Photoshop and which one works best will depend on your image.
Probably the easiest option is simply use the lens blur, but keep in mind that how succesful you are depends a great deal on your image and subject. The example image shown here is a very difficult scene because of the thin blades of grass that stick up into the background.
lensblur.jpg
If we had used a lower aperture setting when composing the shot, those blades sticking up would be in sharp focus will the background remained blurred. Simulating that in Photoshop would be incrediply tendious, so we've settled for "good enough." However, if your foreground subject is sharply and cleanly set out from the background, the task is somewhat easier.
As you can see, to get the effect show above we've duplicated the background, applied a lens blur and then converted that layer to a mask. Then we just very carefully painted around the primary subject to establish the focal plane.
Another way to accomplish the same thing is to use Lens Blur in conjunction with a gradient channel. To do that you need to make sure your image is in RGB mode then click the channels palette and add a new channel.
Now, grab the gradient tool and set the colors to black and white and create a linear gradient so that the area of the image that you want in focus is roughly covered with black.
gradientlensblur.jpg
To check your gradient, select the RGB channel and you'll see the blur appear as a reddish glow. Once you're happy, make sure you have the RGB channel is selected and apply the Lens Blur Filter
This time make sure to select your new channel as the source. Then you can use the focal distance slider and other options to fine tune your blur.
gradientlensblur-filter.jpg
== Conclusion ==
final.jpg
In the end, to create the image above, I used a mixture of both techniques -- starting with a gradient on the channel and then painting in the areas where the dog's head sticks up into the gradient. And as with most things done in an image editor, there are other ways of doing this as well. Be sure to add your favorites.
Once you've mastered the art of the blur, or if you're looking for some inspiration to get started, head over to Flickr where blur aficionados celebrate Bokeh Wednesday with new images submitted to the [http://www.flickr.com/groups/bokehwednesday/ Bokeh Wednesday Pool].
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