page_title: Faint Object Camera
section_title: Imaging examples
hierarchical_section_title: Faint Object Camera / Imaging examples
caption_attribution_description: The European Space Agency's Faint Object Camera on board NASA's Hubble Space Telescope has provided astronomers with the most detailed image ever taken of the gravitational lens G2237 + 0305 — sometimes referred to as the Einstein Cross. The photograph shows four images of a very distant quasar which has been multiple-imaged by a relatively nearby galaxy acting as a gravitational lens. The angular separation between the upper and lower images is 1.6 arcseconds.
context_page_description: The Faint Object Camera was a camera installed on the Hubble Space Telescope from launch in 1990 until 2002. It was replaced by the Advanced Camera for Surveys. In December 1993, Hubble's vision was corrected on STS-61 by installing COSTARS, which corrected the problem with Hubble's mirror before it reached an instrument like FOC. Later instruments had this correction built in, which is why it was possible to later remove COSTARS itself and replace it with a new science instrument.
  The camera was built by Dornier GmbH and was funded by the European Space Agency. The unit actually consists of two complete and independent camera systems designed to provide extremely high resolution, exceeding 0.05 arcseconds. It is designed to view very faint UV and optical light from 115 to 650 nanometers in wavelength. FOC has been compared to a "telephoto" lens, providing a high resolution in a small field of view. FOC could distinguish between two points 0.05 arc-seconds apart.
  The camera was designed to operate at low, medium, or high resolution. The angular resolution and field of view at each resolution were as follows:
caption: The "Einstein cross", discovered in 1985 by J. Huchra, is a large gravitational lens. 1990 Hubble image
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