# Schmidt–Cassegrain

Also called: SCT, catadioptric.

A compact telescope with a mirror and a front corrector plate; long focal length (f/10) in a short tube.

SCTs fold a long light path into a short tube, so an 8-inch is portable and a 14-inch fits on a mount. Their long focal length gives high power easily — great for planets and small objects — but narrow fields; an f/6.3 [focal reducer](https://astropilot.space/glossary/focal-reducer) widens them. They often come on computerised GoTo mounts.

**Related:** [Maksutov–Cassegrain](https://astropilot.space/glossary/maksutov.md), [Focal reducer](https://astropilot.space/glossary/focal-reducer.md), [Central obstruction](https://astropilot.space/glossary/central-obstruction.md), [Dew](https://astropilot.space/glossary/dew.md)

From the AstroPilot astronomy glossary: https://astropilot.space/glossary/schmidt-cassegrain