Behind that he mounted a smaller circular plain glass plate of the same substrate to serve as a corrector plate
to remove the astigmatism in the guider image introduced by its light passing through the 45[degrees] mirror.
In common with SCTs, Schmidt cameras brought light to a focus using a catadioptric combination of a refracting corrector plate
followed by a spherical short-focal-length primary mirror.
In 1930 the Estonianborn German optician Bernhard Voldemar Schmidt (1879-1935) devised a special corrector plate
, a small glass object with a complicated shape that could be placed near the focus of a spherical mirror.
In addition to its f/2.2 spherical primary mirror, the design incorporates a Schmidt corrector plate
that eliminates image-blurring spherical aberration.
The project soon ran into technical difficulties, partly because the astronomers wanted to build two telescopes in one--a Schmidt camera for wide-angle photography, which could be converted into a conventional Cassegrain reflector for spectroscopy when the giant corrector plate
This is true whether we're talking about a reflector's mirror, a refractor's objective, or the corrector plate
of a Maksutov or Schmidt-Cassegrain telescope.
The optical design consists of a full-aperture corrector plate
combined with a Mangin primary mirror and 2-element corrector lens, yielding a 60-mm fully illuminated photographic field.
Because the HyperStar lens and your camera are mounted directly on the SCT's corrector plate
, they form part of the telescope's "central obstruction." While the HyperStar's diameter isn't much bigger than that of the secondary mirror it replaces, cameras can be much larger.
The XLT in the name refers to the Celestron's StarBright coatings, which are applied to the SCT's front corrector plate
and both mirrors, and are designed to maximize the light throughput of the scope.
If I take my 12-inch Schmidt-Cassegrain telescope's cap and cut an off-center hole that just fits between the central obstruction and the corrector plate
's edge, will I have an unobstructed system with all the advantages of a refractor?--Steve Silverman, Costa Mesa, CA
Compared to Maks, the relatively thin Schmidt corrector plate
makes the C6 about 3 pounds lighter, and it requires less time to reach thermal equilibrium when carried from a warm house into the cool night.
A fire extinguisher was found resting on the Schmidt corrector plate
, many sharp nails were shoved inside the telescope from the eyepiece side, and the finderscopes were left in various states of disrepair.