Photography : Astronomy : Behind the Smoke and Mirrors
What's behind the mighty Keck II telescope? This shot was taken at the Cassegrain focus, which is a dock or port for instruments at the base of the massive primary mirror. The white struts at the upper left and right edges of the photo are part of the intricate support structure for the mirrors, which is known by the strange term "wiffletrees". When this port is in use, a camera would be attached to this port at exactly the right spot to catch all of the light collected by the 33 foot (10 meter) wide primary mirror. A telescope is different from a professional photographer's camera in the sense that different instruments are installed on the telescope rather than different lenses installed on the same camera.