Optical reference
Orion SkyQuest XT12 Classic Dobsonian: aperture, focal length and eyepiece fit
What the Orion SkyQuest XT12 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 XT12 Classic Dobsonian | 429x | 0.19 deg |
| Tele Vue 10mm Delos in the Orion SkyQuest XT12 Classic Dobsonian | 150x | 0.48 deg |
The XT12 is a large 305 mm f/4.9 Dobsonian, 12 in of aperture at a 1500 mm focal length. Its light grasp reaches faint galaxies and globular clusters, and its 2 in focuser takes the widest low-power eyepieces.
Because magnification is the telescope's 1500 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 60x here and a 10 mm eyepiece gives 150x. The highest useful magnification is about 610x (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.