Optical reference
Orion SkyQuest XT10 Classic Dobsonian: aperture, focal length and eyepiece fit
What the Orion SkyQuest XT10 Classic Dobsonian 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 |
|---|---|---|
| Tele Vue 3.5mm Nagler Type 6 in the Orion SkyQuest XT10 Classic Dobsonian | 343x | 0.24 deg |
| Celestron Omni 9mm Plossl in the Orion SkyQuest XT10 Classic Dobsonian | 133x | 0.38 deg |
The XT10 is a fast 254 mm f/4.7 Dobsonian: 10 in of aperture at a 1200 mm focal length. It gathers far more light than an 8 in for fainter deep-sky objects, and its 2 in focuser takes long wide-field eyepieces.
Because magnification is the telescope's 1200 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 48x here and a 10 mm eyepiece gives 120x. The highest useful magnification is about 508x (roughly twice the aperture in millimetres), 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.