Figure 3-2
A cutaway view of the light path of the Newtonian optical design
The Schmidt-Cassegrainoptical system (Schmidt-Cass or SCT for short) uses a combination of mirrors and lenses and s referred to as a compound or catadioptric telescope. This unique design offers large-diameter optics while maintaining very short tube lengths, making them extremely portable. The Schmidt-Cassegrain system consists of a zero power corrector plate, a spherical primary mirror, and a secondary mirror. Once light rays enter the optical system, they travel the length of the optical tube three times.
Inside the optical tube, a black tube extends out from the center hole in the primary mirror. This is the primary baffle tube and it prevents stray light from passing through to the eyepiece or camera.
Figure 3-3
A cutaway view of the light path of the Schmidt-Cassegrain optical design
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