By Stephen Schweickart
So, if we’re all on the same page and you want to start adding some SWEET shallow depth of field to your productions, there are three main things you’re going to want to keep in mind:
One: You should put as much space between your subject and the background as possible. Having your subject significantly separated from the background will throw the background out of focus and create that nice, smooth blur that we’re looking for to give our image or video that three dimensional feel. But slow down turbo! It’s not that simple—your camera needs to be set up correctly too; which brings me to my next point….
Two: Grab a lens with a large maximum aperture. Once your subject is far enough from the background (usually 15′ or so should do the trick) the next step will be to use a fast lens with a maximum aperture setting of f/ 2.8 or lower – f1.8 or lower is even better. As we’ll see in number three, it’s not the only factor, but in general, your aperture settings will play a huge role in determining your depth of field. The lower the f-stop, the more shallow the depth of field and the more “bokeh bits” in your image. The higher the f-stop setting, the more everything will be in focus – less bokeh. To exaggerate an example of this you can point your camera at small light (like a Christmas light) and go through your aperture settings starting at f-15 and go down as low as your lens will allow. As your f-stop gets lower, you should see the light become a smooth round circle as it goes out of focus.
Three: Pay attention to your focal length – this makes a big deal too. If you’re not sure the focal length of your lens, just pick it up and take a look—it should be expressed as millimeters somewhere on the body of the lens or right on the front. The higher the focal length—200mm for example, the further away your lens will reach and the easier it will be to create shallow depth of field. A lens with a shorter focal length will require you to put more distance between your subject and background in order to throw that background out of focus and get some bokeh happening.