Entry to the pits was a lot easier then than it is today, with just a little care combine with picking the right moment enthusiasts could spend quite sometime wandering around the pits taking a few snaps.
During the seventies and into the eighties the racing was much closer and more exciting than it is today, the main factor being that the majority of teams were using the Ford Cosworth engine and aero dynamics were less influential. The downside was that the racing was much more dangerous and drivers really were risking their lives every time they raced. It might not be as exciting but at least Grand Prix racing is safer today.
I still remember the speed that James Hunt went through Copse Corner during the 1976 Grand Prix, he looked visibly quicker than any other driver, and he was. James Hunt won the race but unfortunately Ferrari lodged a protest and two months after the race James Hunt and Mclaren were disqualified for a technical infringement.