Major international airports can get very busy with a steady stream of departures and arrivals. Often it is hard to visualize how much traffic there is. It can be that the best time is at night when the string of lights strung out on the flightpaths makes it clearer just how much is out there. If you can find yourself in line (or almost in line) with the runways, you can get a better view of what is moving out there. The reversal of operations at SFO provided an opportunity to see the jets spread out across San Francisco Bay towards Oakland as they came in to land. A bit of a long lens and you can see several aircraft in a single frame.