Celestron Omni CG-4 Telescope Mount Telescope Basics - Page 2

light-gathering power for the dollar. Because the light path is intercepted and reflected out to the side, you can have focal lengths up to 1000 mm and still enjoy a telescope that is relatively compact and portable. A Newtonian Reflector telescope offers such impressive light-gathering characteristics you can take a serious interest in deep space astronomy even on a modest budget. Newtonian Reflector telescopes do require more care and maintenance because the primary mirror is exposed to air and dust. However, this small drawback does not hamper this type of telescope's popularity with those who want an economical telescope that can still resolve faint, distant objects. Focal Plane Focuser Secondary Mirror Primary Mirror A cutaway view of the light path of the Newtonian optical design The Schmidt-Cassegrain and Maksutov The Schmidt-Cassegrain optical system (Schmidt-Cass or SCT for short) uses a combination of mirrors and lenses and is 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. The Maksutov optical system is similar to the SchmidtCassegrain but can have a secondary mirror or an aluminized spot in place of the secondary mirror. There are many variations of the Maksutov design. A cutaway view of the light path of the Schmidt-Cassegrain optical design 2