Explore Scientific


Explore Scientific 20" f/3.6 Newtonian Truss Tube Dobsonian Telescope

Completely redesigned, the Explore Scientific 20" f/3.6 Truss Tube Gen 2 Dobsonian Telescope features improved stiffness and load-bearing capacity of the optical components to safely carry the large primary mirror and move the entire system smoothly without any vibration.

Its oversized parabolic primary mirror is highly reflective and corrects spherical aberration to eliminate distortion across the entire field of view, especially at the edges.

The low-weight rocker box provides a rock-steady observational platform with high mobility and very low vibration.


  • All connections of the tube structure are welded, with no rivets or screws.
  • Open aluminum truss design maintains performance while reducing weight, without sacrificing strength or stiffness
  • Silvered aluminum mirror coatings boost reflectivity to greater than 94% to maximize image brightness
  • Primary mirror and rocker box fans help to maintain mirror temperature to reduce distortion
  • Six supporting base feet improve stability to improve vibration suppression and smooth rotation
  • High altitude bearings enable a wide adjustment and travel range, with smooth movement and limited vibration
  • Tension control handle allows for smoother rotation to reduce vibrations and limit overcompensation
Focal Lenght 1826mm
Focal Ratio f/3.6
Primary mirror diameter 50cm
Secondary obstruction 24%
Mirror cell support points 18
Truss pole length 100cm
Truss pole diameter 25mm
Secondary cage assembly diameter 57cm
Secondary cage assembly weight 8lb
Secondary cage assembly height 95cm
Mirror box/rocker box height 56cm
Mirror box weight 105lb
Height to center of eyepiece at zenith 170cm
Theoretical limiting stellar magnitude 0.23 arcsec
Theoretical Rayleigh limit 0.23 arcsec
Theoretical limiting magnitude 16.19
Theoretical maximum magnification 1000x


Note: Mirror weight can vary because of the manufacturing process; these values are approximate