Orion SkyQuest XT6 Classic Dobsonian: 150 mm aperture, 1200 mm focal length, f/8, Newtonian reflector (parabolic primary). The magnification, true field and exit pupil each eyepiece gives, and the barrel, mount and camera adapter that fit.

Updated 05 September 2026.

Optical reference

Orion SkyQuest XT6 Classic Dobsonian: aperture, focal length and eyepiece fit

What the Orion SkyQuest XT6 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

Aperture
150 mm (5.91 in)
Focal length
1200 mm
Focal ratio
f/8
Optical design
Newtonian reflector (parabolic primary)
Focuser / eyepiece barrel
1.25 in rack-and-pinion focuser
Mount
Manual Dobsonian base
Highest useful magnification (2x aperture rule)
about 300x

Eyepiece ladder

2 pairings

The XT6 is a 150 mm f/8 Dobsonian, a slow 6 in that is gentle on eyepieces and shows sharp lunar and planetary detail. Its 1200 mm focal length gives comfortable medium power with common 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 300x (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.

Match an eyepiece, mount or camera

Questions and answers

What is the aperture of the Orion SkyQuest XT6 Classic Dobsonian?

150 mm (5.91 in)

What is the focal length of the Orion SkyQuest XT6 Classic Dobsonian?

1200 mm

What is the focal ratio of the Orion SkyQuest XT6 Classic Dobsonian?

f/8

What is the optical design of the Orion SkyQuest XT6 Classic Dobsonian?

Newtonian reflector (parabolic primary)