Reflecting telescope#Schiefspiegler

The cutter - Schiefspiegler is a reflecting telescope primarily for observation of the sky, which was developed by Anton Kutter. It represents a modification of the cassegrainschen reflector, the mirrors are tilted against each other. This design allows an image without vignetting by the secondary mirror and holder.

By tilting the mirror act as error coma, astigmatism and spherical aberration which must be corrected. Overall, a z -shaped beam path results (as opposed to Yolo Schiefspiegler with its X-shaped beam path ) and thus even at long focal length instruments comparatively short length, but also an unusual and somewhat bulky design.

To correct the error, there are several options:

• One can keep ( to lens diameter ratio focal length) small aberrations of the convex secondary mirror to an accurate measure diagonally filters ( anastigmatic design) and by a long focal ratio.
• The secondary mirror can be ground aspherical.
• In the beam path after the secondary mirror in addition a correction lens (Wedge lens ) or a lens system is installed ( catadioptric design).

Only in this way Schiefspiegler are to use for astronomical observations.

The image definition and contrast performance of a Schiefspiegler is superior to that of a Newtonian telescope or Cassegrain telescope, since no interfering components in the beam path are. Disadvantage compared to a refractor of the same aperture at the open construction generally available, slightly greater sensitivity to local air currents ( Schlieren, flickering of the image ). Cutter recommended its structure up to a maximum opening of 16 inches (400 mm).