Photos with shallow depth of field are a very popular look in most genres involving people in some way, but they also require pricier lenses to shoot. This helpful tutorial will show you how to fake the effect using Photoshop.
Coming to you from Jesús Ramirez of the Photoshop Training Channel, this fun tutorial will show you two methods for simulating shallow depth of field in Photoshop. From both the perspective of the amount of time it takes and realism, it might be better to just pick up something like a wide-aperture 85mm lens, but if you don't have one or for some reason, your photo was already shot at a narrower aperture, this will show you how to add the effect yourself. I personally recommend the second method, which uses depth maps. By showing Photoshop the relative distance of different elements in the image, you can help it build a proper three-dimensional map of a two-dimensional image, thereby allowing it to more realistically mimic blur that increases with distance from the focus point. As will all techniques like this, be careful not to overdo it, which will make the image look artificial; less is definitely more.