A long exposure photograph of the Golden Gate Bridge in San Francisco, CA, USA. In particular, this is a photograph of the northern tower, with San Francisco in the background. It is a 15 second exposure taken just as the sun was setting.
The area around the San Francisco Bay, is commonly referred to as the "San Francisco Bay Area," or just the "Bay Area" for short. This includes San Francisco, San Jose, Oakland, Silicon Valley, Mountain View, Berkeley, Napa, and many other notable locations. There really is no clear definition of the Bay Area, with different people defining different boundaries. I have heard a few different definitions myself while living here.
The iconic Golden Gate Bridge is probably one of the most photographed bridges in the world. There are certainly no shortage of photos of this bridge. Doing a quick image search on Google will show you exactly what I mean. That said, I am a photographer living in the Bay Area. As such, I have a few of my own to contribute to the growing pile, and this photo is one of them.
The Golden Gate Bridge spans the entrance to the San Francisco Bay from the Pacific Ocean. The bridge connects San Francisco (southern end) and Sausalito (northern end) along the scenic California State Route 1 .
Long exposure photography, as the name implies, simply refers to photographs taken with relatively long exposure times. Typically, the photographer wishes to capture the movement of one or more elements within a scene over the course of the exposure. The resulting photograph then reflects this movement in some way. This technique can be used to create various effects, and thus is a useful technique for photographers to know.
Taking long exposure photographs can be a bit tricky. First and foremost, the photographer needs to imagine what is going to happen in the scene over time and how that will affect the final result. There are several technical aspects to take into account as well.
As with all forms of photography, managing the light in a photograph is important. Long exposure times can add yet another layer of complexity to lighting. Not only does the light build up over a longer period of time, but it may also move around and/or change in intensity. The exposure settings on the camera also govern how the movement will be captured, including how much overall movement is captured and how much each element of the scene contributes to the final image. Many factors, such as how bright an object is, how reflective it is (e.g. glossy vs matte), how fast it is moving, the use of flashes, and so on, all play a role in how an object will show up in a long exposure photograph.
Secondary effects, such as camera shake and sensor noise, have a higher chance of affecting long exposure photographs as well. Digital camera sensors tend to generate more noise when they are exposed for longer periods of time. Camera shake can become a factor as well. Even small, subtle movements can affect the sharpness of the image. For example, cameras are commonly placed near roadways when photographing the light trails created by cars driving at night. Vibrations caused by those cars can subtly and constantly shake the camera, introducing a slight blur in the final photograph.
More examples of long exposure photographs that I have taken can be found here.