I spotted this MH-65 Dolphin from USCG Air Station San Francisco circling above the Computer History Museum in Mountain View, California. I think it was escorting the caravan that was taking Israeli Prime Minister Benjamin Netanyahu to meet with Governor Jerry Brown.
Nikon D800, Nikkor AF-S 300mm f/2.8G, ISO 200, 600mm, 0 EV, f/5.6, 1/2,000s
I used the Nikon AF-S Teleconverter TC-20E III with the 300mm lens. Quite a heavy and unwieldy set-up when the camera is pointed almost overhead. Even at 1/2,000s, the helicopter rotors have a bit of motion blur.