Sweeney Ridge SFO Time-Lapse: Airplanes, Cars, and Clouds
Sweeney Ridge Nike missile site
The weather forecast and sky chart for Pacifica looked promising, and I've always wanted to shoot the ruins of the Sweeney Ridge Nike missile site at night. SF-51C was an Integrated Fire Control (IFC) site to identify targets, and then the missile would be launched, guided, and detonated. The Sweeney Ridge site now contains 4 buildings in various states of decay, perched on a hill overlooking the San Francisco Airport on one side, and the ocean at Rockaway Beach on the other. On a clear day or night the views are incredible.
Sweeney Ridge is part of the Golden Gate National Recreation Area (GGNRA), and is legal to visit at night. In addition to the former Nike buildings, Sweeney Ridge is also where the Spanish first saw the San Francisco Bay in 1769. Captain Gaspar de Portola and 60 men rode up from San Diego, looking for the Monterey Bay. They were smart and visited in October. Fall is a great time to visit this location, and spring can also have clear weather and wildflowers.
Hiking up Sweeney Ridge
The easiest way to get to the Nike site is to take the Sneath Lane exit from Highway 280, and drive up the hill to the end of the street. Hike 1.3 miles up the paved path to the ridge, and turn right to follow the paved path another 1/2 mile to the Nike site. Bay Area Hiker has some good information on the flora and fauna. Bring lots of layers -- it can get windy up on the ridge.
We started our night hike with relatively clear skies lit by the full moon. As we ascended the hill we were met by cold blasts of 20 mph winds. Uphill into the wind with 25 pounds on your back is a good workout. Just when we got to the top of the ridge the fog and clouds started moving in. We explored the building interiors and saw some fresh graffiti and a huge rat. There appeared to be someone sleeping in one of the buildings. So much for shooting interiors. The weather was still reasonably clear over the Bay and SFO, so I decided to shoot a panorama. The wind was really ripping, and the clouds and fog kept obscuring the view. I switched gears and decided to do a time-lapse instead.
Shooting and Post-Processing the Time-Lapse
The camera was set to a manual exposure of 6 seconds at f/8 ISO 400. I used a Canon 5D Mark II with a 24-70/2.8L lens set at 43mm. The exposure was biased to protect the highlights in the airport and city lights. The full moon helped bring just a little bit of blue tonality to the sky. Color temperature was set to 3400K. I shot in high quality small jpeg mode which yields a file that's 2784x1856 pixels. This allows a little bit of room to crop while still maintaining a file that could be full 1080 HD.
After I was happy with my exposure and white balance, I set the camera to continuous drive mode, and locked the cable release. This setup will keep shooting 6 second shots until you run out of batteries or space on your memory card. I ended up shooting the time-lapse for just about an hour. The resulting images were imported into Lightroom where I applied a little bit of highlight recovery, fill light, and sharpening. Next I exported these files at 720x480 at about 100KB each. I used Quicktime Pro to put the time-lapse sequence together, and after some experimenting decided on 10 FPS. I imported the resulting mov file into iMovie to add titles, credits and music.
iMovie File Quality and Compression
The mov file looked great when I played it in Quicktime. After importing the file into iMovie, the video quality looked terrible. The video compression in iMovie was causing pixellated clouds. After a lot of searching and experimenting I figured out a fix to balance the video quality and file size:
- 960x540 is the native size for the Large import setting in iMovie. Using this size for the video that you import, means iMovie doesn't have to change your file size. This size works just fine for the 480 setting on YouTube. I went back to Lightroom and re-did my export at 1080x720 with 140KB files.
- Using H.264 compression in Quicktime Pro leads to a better quality file than letting iMovie compress your video. After creating the time-lapse in Quicktime Pro, I exported the file with the following settings: Best quality, H.264 compression, multi-pass encoding, 960x540 letterbox.
The resulting file was imported into iMovie, and the video quality looked way better. If anyone has alternate ideas for using iMovie to add titles and music without losing video quality I would like to hear your technique. I hope these technical details are helpful, and that you have fun making your own time-lapse videos!