The extra components are installed downstream of the secondary mirror inside the focus tube, and also serve to increase the telescope's focal length. This is how Celestron squeezes 1000mm of focal ...

The Optical Tube Assembly (OTA) measures a 1000mm (f/5) focal length and 200mm primary mirror diameter. Its design is recognized as a 'fast' telescope because of its light-gathering capabilities ...

The big and bold Orion SkyView Pro 8 GoTo Reflector Telescope is aimed at serious stargazers. Its impressive 1000mm focal length is capable of letting our imaginations reach into deep space ...