Optical reference
Celestron C8 optical tube: aperture, focal length and eyepiece fit
What the Celestron C8 optical tube measures, the magnification and true field each eyepiece produces in it, and the barrel, mount payload and camera adapter that fit.
Published specifications
Eyepiece ladder
2 pairings| Pairing | Magnification | True field |
|---|---|---|
| Celestron Omni 6mm Plossl in the Celestron C8 optical tube | 339x | 0.15 deg |
| Celestron X-Cel LX 25mm in the Celestron C8 optical tube | 81x | 0.74 deg |
The C8 is the bare 203 mm f/10 SCT tube behind the 8SE and a generation of imaging rigs. Its 2032 mm focal length is long, so a focal reducer is common for wide-field or deep-sky photography.
Because magnification is the telescope's 2032 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 81x here and a 10 mm eyepiece gives 203x. The highest useful magnification is the published 480x, beyond which the image dims and softens without showing more detail.
The focuser takes 2 in eyepieces, so long 2 in wide-field eyepieces such as the Omni 56 mm fit as well as 1.25 in ones.