Hide selection = ctrl + H Show last hidden = shift + H I think anyway! But to be honest theres an easier way to hide stuff by type, as I'm guessing you wont want to see your cameras again for a bit. In your panels (ie. side / front / persp etc) look in the 'Show' menu - that'll make hiding and showing stuff nice and quick. Hide selection is probably better used for hiding stuff like geometry that's getting in the way or you dont need for a while. Hope that helps mate.