Optical reference

Celestron StarSense Explorer 8-inch Dobsonian: aperture, focal length and eyepiece fit

What the Celestron StarSense Explorer 8-inch 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
203 mm (7.99 in)
Focal length
1200 mm
Focal ratio
f/5.9
Optical design
Newtonian reflector (parabolic primary)
Focuser / eyepiece barrel
2 in Crayford focuser with a 1.25 in adapter
Mount
Manual Dobsonian base (StarSense phone dock)
Highest useful magnification (published)
480x

Eyepiece ladder

2 pairings

This 203 mm f/5.9 Dobsonian pairs a full 8 in of aperture with phone-guided push-to. The 1200 mm focal length is far shorter than an 8 in SCT, so it delivers wide, bright deep-sky fields, and its 2 in focuser accepts long 2 in 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 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.