Nasmyth telescope
The Nasmyth telescope is a mirror telescope developed by James Nasmyth (1808–1890) , the beam path of which is extended by two auxiliary mirrors and deflected out of the telescope tube . It is a combination of the Newton and Cassegrain telescope .
As with the Cassegrain telescope, the light first falls on a parabolically ground concave mirror , the primary or main mirror . This reflects the light to a smaller convex secondary mirror , the secondary mirror . However, with the Nasmyth telescope, it does not reach a hole in the main mirror, but is deflected into the declination axis by a plane mirror ( tertiary mirror ) inclined to the central axis and emerges laterally (Nasmyth focus) , as with the Newton reflector . It is visually identical to the Cassegrain focus .
With an azimuthal mount , the focal point is on the height axis and is therefore independent of the telescope inclination if the inclination of the tertiary mirror is tracked with the zenith angle of the observation (see also Coudé design). Therefore a fixed platform for observers or heavy analysis equipment can be built there.
Another possibility is to make the Nasmyth mirror rotatable. The image can thus be switched, for example, between an eyepiece for visual observation and a camera for astrophotography , or between different measuring devices.
