Other Telescope Designs

There are many telescope designs that have been developed throughout the last couple of centuries. More than just the reflector, refractor and Schmidt-Cassegrain designs have been put into production for amateur use. Two of the more popular of these alternate designs have been the Maksutov and Schmidt-Newtonian designs.

The Maksutov optical system makes use of multiple mirrors to fold a long focal length into a short tube. In order to accomplish this, a thick corrector plate is placed as the first optical element exposed to the sky to correct for spherical abberations. A reflective spot is placed on the back of the corrector plate and this serves as the secondary mirror to reflect the image through a hole in the primary mirror. This design is simpler to make than a Scmidt-Cassegrain design, but the thicker glass components take longer to adjust to temperature changes.

The Schmidt-Newtonian design looks like a standard Newtonian reflector, but the primary mirror is usually a short focal length, spherical mirror that provides very wide fields of view. Then to correct the severe spherical abberation a Schmidt corrector plate is added to the front of the tube.

Usually these telescopes are sold as optical tubes only, although some are sold as part of a fork mounted system. The optical configuration allows very high quality images with good contrast, and as such, compare favorably with refractors for high power observation such as planetary work. Cost per inch of aperture is second only to refractors.