Explore Scientific 20" f/3.6 Truss Tube Gen 2 Dobsonian Telescope

Description

Product Highlights

20" / 500mm Dobsonian Reflector
1826mm Focal Length, f/3.6 Focal Ratio
10:1 2.5" Two-Speed Helical Focuser
Floor-Based Manual Alt-Az Mount
Altitude Tension Clutch
Dual Radial Main-Mirror Fans
Red Dot LED Finderscope
Tool-Free Breakdown and Assembly

Completely redesigned, the Explore Scientific 20" f/3.6 Truss Tube Gen 2 Dobsonian Telescope gets improvements to stiffness and load bearing capacity of the optical components to safely carry the large primary mirror and move the entire system smoothly with greater vibration suppression. All connections of the tube structure are welded, with no rivets or screws.

The ability to produce the large 20" aperture gives users exceptional performance with a low dollar-to-aperture cost. 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 large aperture draws in a tremendous amount of light to present awe-inspiring details of the Moon and planets, make deep sky objects visible even for inexperienced observers, and reveal bright star clusters with resolution down to their core. Its exceptional f/3.65 focal ratio and 10:1 dual-speed 2.5" helical focuser makes this an ideal choice for imaging. The fast focal ratio enables devices to capture images in less time than slower scopes with limited light loss to diffraction and diffusion, while the unique focusing mechanism employed in the helical design gives it the ability to achieve tack-sharp focusing with zero backlash, which rack-and-pinion focusers are generally unable to do. This focuser will accept larger 2" eyepieces so users can enjoy a truly immersive visual experience and will ensure larger imaging sensors are completely covered.

The rocker box provides a rock-steady observational platform with very low vibration, and features high-altitude bearings with aluminum structures that allow for fine adjustment flows at high magnifications, and an array of fans in the box and at the primary mirror allows the telescope to quickly adjust to the ambient air temperature to reduce distortion. Finally, the tension control handle allows users to adjust the settings, allowing them to move the mount easily and smoothly by hand with minimal vibration and maintaining its position when released.

Optical Tube Assembly

Open aluminum truss design maintains performance while reducing weight, without sacrificing strength or stiffness
Oversized 20" / 500mm aperture draws in the light required for viewing deep space objects, like wispy nebulae and splitting binary stars, and reveals stunning lunar and planetary details
Fast f/3.6 focal ratio ensures high light transmission through the optical system with limited diffraction or diffusion
Long 1826mm focal length produces a high magnification potential
Silvered aluminum mirror coatings boost reflectivity to greater than 94% to maximize image brightness
120mm secondary mirror, 24% obstruction
Primary mirror and rocker box fans help to maintain mirror temperature to reduce distortion
Fans run on eight user-supplied AA batteries
Laser-engraved center mark on primary mirror enables easier collimation
Includes collimation assist tool for adjustments in the field

Mount

Manual alt-azimuth rocker mount design
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
Assembles and disassembles without tools

Focuser

Dual-speed focusing mechanism with 10:1 reducer enables fast coarse and precision fine focusing
Large 2.5" helical design provides strength and stability for large and heavy eyepieces, and moves the drawtube forward and back without rotation to maintain optical performance through eyepiece or imaging system
Accepts large 2" eyepieces to ensure a relatively large field of view at all magnification to keep objects within the eyepiece for the maximum amount of time before adjustments to the mount are required
Helical focusers use a toothless design that allows for smooth and precise focusing without backlash

Specifications

Optical Design	Dobsonian reflector
Aperture	20" / 500 mm
Focal Length	1826mm
Focal Ratio	f/3.65
Eyepiece Barrel Diameter	2"
Diagonal	N/A
Finderscope	Red dot LED
Tripod	None
Mount Type	Manual alt-az
Power Source	8 x AA batteries, for fans
Optical Tube Dimensions	Height, Fully Assembled: 70.5" / 179.1 cm Width: 27.0" / 68.6 cm
Weight	116.0 lb / 52.6 kg

BOX1: 60x60x38cm approx. 44 kg ; BOX2: 69x69x33cm approx. 17 kg ; BOX3: 15x15x115cm approx. 4 kg

In the Box

Explore Scientific 20" f/3.6 Truss Tube Gen 2 Dobsonian Telescope

Collimation Assist Tool

Red Dot LED Finderscope

Limited 1-Year USA Warranty, Extendable to Transferrable Lifetime Warranty with Registration

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