With a little work, it's possibly to create fairly convincing lens blur using Photoshop. This tutorial will show you just how to do just that.
Sometimes, you just don't have an ultra-wide aperture telephoto lens with you to get that sweet, buttery background blur. Maybe it's because you shot at a narrower aperture due to the sun or maybe you only brought a travel lens. Either way, there's no arguing the subject-isolating benefits of a well-blurred background. This helpful tutorial from PiXimperfect will show you how to fake that shallow depth of field effect using Photoshop. The real key to the entire puzzle is creating a depth map; since depth of field blurring depends on the spatial dimension of distance to the lens, which is unfortunately the dimension lost when creating a two-dimensional photograph, we need a way to recreate that information for Photoshop, which this tutorial teaches. While it's a great effect that's certainly handy to have in your bag of tricks, if you do like the look, I recommend picking up a short telephoto prime if you plan on using it often, as you probably don't want to go through the entire Photoshop process each time. Nonetheless, it's good to know how to do this for the times you might need it.