One of the great things about 'Ghostbusters' is the economy with which it's written and shot. There are only ten individual shots in this whole three scene sequence, including an establishing shot of the firehouse. The middle scene is done in a oner (across the street from the library and I'd guess shot on the same day). We also get very few closeups. We get one on Ray and one on Peter in the first scene at Columbia, but we linger on neither, and then we get one brief reaction shot of the estate agent. We never see a single closeup of Egon. This means we almost always see characters sharing the frame with each other and with their environment in medium shots without many cuts. Meanwhile the script is tight, the jokes are good, and there's very little that could be thrown away. This is all very efficiently done. In less than three minutes of screen time we go from them being disgraced scientists with no Plan B to having conceived of the business, got the money and found a location. When we next see them onscreen it's the TV commercial (which appears in the background of a scene that is establishing Dana, Lewis and Zuul), and that's it: like that they're already the Ghostbusters, and we have our major conflict. This movie is a classic for a few reasons, but this is one of them: it is technically very well made.