Just starting out in photography and want to learn how to blur your backgrounds when shooting portraits? Here’s a 4-minute video from Sheldon Evans that looks at how you can create a beautiful bokeh in your photos.
A soft background, or bokeh, is achieved by using a shallow depth of field. This comes from using a lens with a large maximum aperture (indicated by a low f-number like f/2.8).
The smaller the f-number, the shallower the depth of field you can achieve. This shot was taken at a very wide f/1.4 aperture:
The same scene shot at f/14 shows a lot more of the scene in focus as the depth of field is now larger:
But it’s not all about the size of your aperture: a lens’ focal length matters too. A longer focal length will create a shallower depth of field when compared at a constant f-number.
If the background is further from your subject, then you’ll see a nicer bokeh effect too.