Nitpick: 'collimated' is a technical term for a beam of light where all the rays are exactly parallel. When using 'collimated' in the article, the author means 'focused' or 'narrow' - as in, the focused beam of light emanating from a spotlight, which spreads out slower than an omnidirectional light, but isn't strictly parallel.

You'd think that an article titled 'Photography for geeks' would take some care to get the technical terms right!