Surprisingly not. The trick is usually to build pylons (or other cannons) such that they protect the cannons from being attacked by probes. Building them out of sight is usually too slow as a rush.
Still, he didn't do that either.
Still, he didn't do that either.
Typically, you don't see more than 1-2 photo cannons, because you don't usually want to "over-invest" and lose what advantage you gain.