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Camera lenses and footprint

The KidSat camera comes with several different lenses. Three lenses were carried into orbit on the first KidSat flight: a 50mm lens, an 85mm lens, and a 180mm lens. (The number refers to the focal length of the lens, which is given in millimeters). The 50mm lens was installed on the camera during the first part of the flight (before the shuttle docked with Mir); the 180 mm lens was installed during the second part of the flight (after the shuttle had separated from Mir); the 85mm lens was not used. It is likely that the same three lenses will be carried on STS-81.

The area on the surface of Earth that would be captured in one photograph is called the "footprint" of the camera.

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The camera footprint depends on the focal length of the lens. The focal length determines both the field of view of the camera (and therefore how large an area on the Earth is included in the picture). The longer the focal length, the narrower is the field of view.

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This schematic illustrates the field of view for a 180mm lens and a 50 mm lens.

The focal length also determines the magnification of the lens. The longer the focal length, the higher the magnification, and the more detail you can see in the photograph.

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