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Camera Obscura (San Francisco, California)
Encyclopedia
The Camera Obscura in San Francisco is a large-scale camera obscura
and is listed on the National Register of Historic Places
. It is located near the Cliff House
restaurant perched on the headlands on the cliffs just north of Ocean Beach
on the western side of San Francisco, California
. The Camera and restaurant are currently owned by the National Park Service
as part of the Golden Gate National Recreation Area
.
When the fourth Cliff House opened in 1937, the owner was approached by businessman Floyd Jennings with the idea of adding a camera obscura to the cliffs behind the restaurant. It was installed on the site in 1946 and has been in continuous operation since then.
at the top of the building slowly rotates, making a full revolution in about six minutes, allowing for a 360º view around the building.
Light enters the building via an angled mirror in the metal hood. It then passed through a lens with a 150 in. (381 cm) focal length
and is projected onto a parabolic white "table" in a black room. The origin of the lens is uncertain but it appears to have been part of a telescope, likely manufactured by the Clark Lens Company
of Cambridge, Massachusetts
.
Camera obscura
The camera obscura is an optical device that projects an image of its surroundings on a screen. It is used in drawing and for entertainment, and was one of the inventions that led to photography. The device consists of a box or room with a hole in one side...
and is listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
. It is located near the Cliff House
Cliff House, San Francisco
The Cliff House is a restaurant perched on the headlands on the cliffs just north of Ocean Beach on the western side of San Francisco, California...
restaurant perched on the headlands on the cliffs just north of Ocean Beach
Ocean Beach, San Francisco, California
Ocean Beach is a beach that runs along the west coast of San Francisco, California, United States, at the Pacific Ocean. It is adjacent to Golden Gate Park, the Richmond District and the Sunset District. The Great Highway runs alongside the beach, and Cliff House and the site of the former Sutro...
on the western side of San Francisco, California
San Francisco, California
San Francisco , officially the City and County of San Francisco, is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of 7.15 million people which includes San Jose and Oakland...
. The Camera and restaurant are currently owned by the National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
as part of the Golden Gate National Recreation Area
Golden Gate National Recreation Area
The Golden Gate National Recreation Area is a U.S. National Recreation Area administered by the National Park Service that surrounds the San Francisco Bay area. It is one of the most visited units of the National Park system in the United States, with over 13 million visitors a year...
.
History
Cameras obscura, devices which project an image of the surroundings onto a surface using only existing exterior light sources, usually sunlight, have a long history in San Francisco. The first recorded reference to one in the city is from the 1860s in an attraction called Woodward's Gardens. A previous incarnation of the Cliff House was noted to have had a camera obscura on its fourth floor in 1896. This camera obscura was destroyed when the restaurant burned down in 1907.When the fourth Cliff House opened in 1937, the owner was approached by businessman Floyd Jennings with the idea of adding a camera obscura to the cliffs behind the restaurant. It was installed on the site in 1946 and has been in continuous operation since then.
Technology
The San Francisco Camera Obscura projects an image onto a horizontal viewing table via a reflected image from a viewpoint at the top of the building. A metal hood in the cupolaCupola
In architecture, a cupola is a small, most-often dome-like, structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome....
at the top of the building slowly rotates, making a full revolution in about six minutes, allowing for a 360º view around the building.
Light enters the building via an angled mirror in the metal hood. It then passed through a lens with a 150 in. (381 cm) focal length
Focal length
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus...
and is projected onto a parabolic white "table" in a black room. The origin of the lens is uncertain but it appears to have been part of a telescope, likely manufactured by the Clark Lens Company
Alvan Clark & Sons
Alvan Clark & Sons was an American maker of optics that became famous for crafting lenses for some of the largest refracting telescopes of the 19th and early 20th centuries...
of Cambridge, Massachusetts
Cambridge, Massachusetts
Cambridge is a city in Middlesex County, Massachusetts, United States, in the Greater Boston area. It was named in honor of the University of Cambridge in England, an important center of the Puritan theology embraced by the town's founders. Cambridge is home to two of the world's most prominent...
.