Optical reference
Orion SkyQuest XT4.5 Classic Dobsonian: aperture, focal length and eyepiece fit
What the Orion SkyQuest XT4.5 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 |
|---|---|---|
| Celestron Omni 6mm Plossl in the Orion SkyQuest XT4.5 Classic Dobsonian | 150x | 0.33 deg |
| Celestron Omni 15mm Plossl in the Orion SkyQuest XT4.5 Classic Dobsonian | 60x | 0.83 deg |
The XT4.5 is a compact 114 mm f/7.9 Dobsonian, a small aperture on a simple base that is easy for a beginner to point. Its 900 mm focal length is friendly to mid-length eyepieces for the Moon, planets and brighter deep-sky objects.
Because magnification is the telescope's 900 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 36x here and a 10 mm eyepiece gives 90x. The highest useful magnification is about 228x (roughly twice the aperture in millimetres), beyond which the image dims and softens without showing more detail.
The focuser takes 1.25 in eyepieces, so use 1.25 in eyepieces; a long low-power 2 in eyepiece will not fit this focuser.