I thought this was pretty good.
So you do the mission 'The Wrong Side of the Tracks' and when you come of the bike Chad was riding, wait outside the school gates and get your camera out.
Now turn to face where Earnest and the Nerds are standing waiting for you and Algernon and zoom in. Now press the button, if you dont get it then slowly edge forward and continue taking his photo until it's succesful.