X-Nico

unusual facts about Secondary mirror


Green Bank Telescope

The offset support arm houses a retractable prime focus feed horn in front of the 8 m subreflector and eight higher-frequency feeds on a rotating turret at the Gregorian focus.


SkyMapper

The telescope has a compact modified Cassegrain design with a large 0.69 m secondary mirror, which gives it a very wide field of view: its single, dedicated instrument, a 268-million pixel imaging camera, can photograph 5.7 square degrees of sky.


see also

Anton Kutter

Kutter was awarded two golden medals at the Venice Biennale and he invented the well-known Schiefspiegler telescope which is a modified Cassegrain reflector featuring superb optical definition due to an off-axis secondary mirror.