If a blurry background was all there was to it, this would be a short article. The goal is to not only have a blurry background, but one that “pops” with explosions of light and color like a Monet painting, framing a perfectly focused subject.
To experiment with the art of bokeh you’ll need a fast lens, a selection of ND (Neutral Density) filters and a lot of patience. Don’t worry if you can’t get all that right at first, before the end of the article I’ll show you how to cheat and get a similar effect in post-processing.
Start by gaining as much separation between your subject and the background as possible. In many instances you won’t have any control over this, when you do get as much distance as you can.
Next open your lens to the widest possible aperture, the lowest f-stop it can achieve. In most good lenses, like the Canon 50mm “Nifty Fifty”, that will be f/1.4 to f/1.8. That narrows the focal plane, the distance that is in focus on either side of the subject, and throws the background out of focus.
If you’re outside and don’t have the exposure latitude to open the lens all the way, this is where your neutral density filters come in. Add your ND filters, starting with 0.9. You can stack them if necessary to achieve the proper amount of light reduction.
Don’t be afraid to use fill flash or a reflector to help isolate your subject even further.
Look for backgrounds with bright lights or sunlight filtered through trees or foliage. Be careful as sometimes these settings can be meter cheaters. You might need to lock exposure on your subject, then frame your picture.
Using Post Processing
Perhaps you’re working with a photo taken sometime before you were thinking about bokeh or just a snapshot you decided it might look good. You can achieve a very similar effect in post processing.
For this article I’m going to describe the steps in GIMP, an open source image manipulation program. You can look here for a similar process in Photoshop.
Good practice says step one is to make a clean copy of your image before doing any manipulation. That way if you accidentally save the image while you’re working you don’t save over your original. Ready?
In GIMP, use the Path tool to outline the subject.
On the toolbox click the Selection from Path button.
In the Select menu choose Invert to select the background.
Under Filters > Blur select Gaussian Blur. You can also try Tileable Blur which is a script with several built-in functions.
You may have to experiment with the settings to exactly the look you’re after but that’s the great thing about digital photography is you have almost unlimited opportunity to explore.
Even a group for when the hobby goes too far.
As always, go shoot something and have fun.