> he needs to lend that stuff to Andrew pronto to find out
This lens isn't as impractical on a bustling street, but you still be far enough away that they don't pay attention to you, pick someone who's already looking at something in roughly the direction you're facing them from, and snap what's actually a candid picture where they appear to be looking at the camera. You get far more natural looks than you do if you're asking for poses. It also zooms out to make a great medium-wide angle lens. It's the lens you pack when you don't want to think about which lens to pack.