Sounds like you're after a shallow depth of field.
You should be able to achieve a similar effect with the Canon 50 at around f/1.8, but you'd need to be shooting as wide as possible. I also wouldn't be at all surprised if he's got a reflector or flash out of shot to balance the light in some of those.
Other things to bear in mind when trying to get that shallow depth of field, is to shoot with as wide an aperture as possible - I'd normally flick over to "Av" mode, and get a low f-stop number (so 1.8 with the 50mm prime lens). Then get as physically close as possible.
Finally, if you're manually focusing, err on the focusing ahead of the subject -- the way that depth of field works, you get an area (depth) that appears to be focused, by having the subject in the back half, the background behind is going to appear to be even more off focus, as desired. I believe this is another technique he's using, apparent when you look at the ground with more of the ground ahead of the subject in focus than even to the back of their feet.
If you're still not happy, then you could and a really gentle blur in post-production, although I'm always a fan of trying to get it right in camera, as it will have a more realistic feel to it.