Sometimes, what you do not see in a picture is as important as what you do see.  Like in this picture:

There are four reasons I may want to blur the background: It would be distracting. And it is not really part of  the story. And implying is sometimes best. And I might not want it in the image for “facebook/SFW-reasons”.

So I shot this at 800 ISO, 1/160th second, f/1.8, using my 85mm f/1.2 lens.  Yes, f/1.8, and the gives me extremely shallow depth of field, and an extremely blurred background.

Wonderful, but it necessitates me using a very steady hand. After I focus (on the eyes) neither I nor the model must change our distance even by a few millimeters.

Here’s one more, for good measure:

Now, the lens. My 85mm lens on a full frame camera is equivalent roughly to a 50mm lens on your crop camera. And the 50mm f/1.8 lens incredibly affordable and great. So.. if you do not have one, get one. And if you do, use it!