LF4 Depth-of-field

Trying to figure out how to create a sort of a depth-of-field effect here. The iPhones are supposed to be fully in focus, the iPads somewhat behind them, and the iMac and Macbook further behind. I’ve never really gotten into photography, so I’m not sure how to go about faking an effect like this (been spending a lot of time staring at things with one eye closed, heh.)

What kind of filter(s) should I be using? I would’ve thought Photoshop’s lens blur would’ve been perfect, but it made the edges of the devices go all weird and dark. Pixelmator’s gaussian blur seems to be the best so far, but it does look really “fake.” Could I perhaps make use of Quartz Composer’s defocus filter somehow?

Should the iPads be as blurred as the iMac and Macbook, or slightly less blurred as they are now?