Schmidt Cassegrain telescope info

Schmidt Cassegrain

The Schmidt Cassegrain is a catadioptric telescope that combines a cassegrain reflector's optical aisle with a Schmidt corrector bowl to accomplish a bunched ample apparatus that uses simple all-around surfaces.

The Schmidt Cassegrain was invented in 1940 by James Gilbert Baker as a modification of Bernhard Schmidt's 1931 Schmidt camera. As in the Schmidt camera this architecture uses a all-around primary mirror and a Schmidt corrector bowl to actual for all-around aberration. In this Cassegrain agreement the arched accessory mirror acts as a acreage flattener and relays the angel through the perforated primary mirror to a final focal even amid abaft the primary. Some designs accommodate added optical elements (such as acreage flatteners) abreast the focal plane.

The Schmidt Cassegrain architecture is actual accepted with customer telescope manufacturers because it combines accessible to accomplish all-around optical surfaces to actualize an apparatus with the continued focal breadth of a refracting telescope with the lower amount per breach of a absorption telescope. The bunched architecture makes it actual carriageable for its accustomed aperture, which adds to its marketability. Their aerial f-ratio agency they are not a advanced acreage telescope like their Schmidt camera antecedent but they are acceptable for added attenuated acreage abysmal sky and all-embracing viewing.

While there are abounding variations, (both mirrors spherical, both mirrors aspherical, or one of each) they can be disconnected into two arch architecture forms: bunched and non-compact. In the bunched form, the corrector bowl is amid at or abreast the focus of the primary mirror. In the non-compact, the corrector bowl charcoal at or abreast the centermost of curvature (twice the focal length) of the primary mirror. Typical examples of the bunched architecture are Celestron and Meade Instruments bartering instruments, accumulation a fast primary mirror and a small, acerb arced secondary. This yields a actual abbreviate tube length, at the amount of acreage curvature. Best bunched designs from Meade and Celestron accept a primary mirror with a focal arrangement of f/2 and a accessory with a abrogating focal arrangement of f/5 acquiescent a arrangement focal arrangement of f/10. One notable barring is the Celestron C-9.25, which has a primary focal arrangement of f/2.3 and a accessory focal arrangement of f/4.3, the aftereffect actuality a hardly adulate acreage and a hardly best tube aspect arrangement than best added bunched designs.

Non-compact designs accumulate the corrector at the centermost of curvature of the primary mirror. One actual well-corrected architecture archetype would be the concentric (or monocentric) Schmidt-Cassegrain, area all the mirror surfaces and the focal apparent are concentric to a distinct point: the centermost of curvature of the primary. Optically, non-compact designs generally crop bigger abnormality alteration and a adulate acreage than a bunched design, but at the amount of best tube length.

Schmidt Cassegrain