Wedding photographer Ryan Brenizer invented this really clever technique which is called “The Brenizer Method”. It’s using a telephoto lens to create a very shallow depth of field as if shot with a wider angle lens. This technique makes a dSLR image look like it was shot by medium format.
I have been expiermenting with this technique for several years now, and gradually I have become better at it.
The baisic way to do it is as such: Using a telephoto-ish lens with a shallow depth of field, like the canon 50mm F1.8 lens[on crop sensor] you photograph a scene like you would a panorama, but instead of just on layer photos high, you make it several photos high. Meaning when shooting with that lens, have it at it's shallowest depth of field, then shoot the whole scene in small pieces. [it's hard to explain!] Think of how you paint a wall with a roller. you make several passes to fill it all in, but do that with a camera. Eventually you might have 10-50 photos shot at a really shallow depth of field, which you then merge in photoshop's photomerge function. And out comes a photo like the above.....with a little work.
To see a gallery of Ryan's photos using this technique, go here. Trust me, it's worth clicking though.
For better tutorials go here[the best one!], here and the official flickr group with lots of help and photos is here.
[youtube http://www.youtube.com/watch?v=UsMnRxmeJ74&w=1000&h=538]