The power of a 20" aperture with state-of-the-art OnStep GoTo — find and track any of 30,000+ objects
automatically via WiFi, Bluetooth, or the Smart Hand Controller. All-metal CNC construction with folding ALT
bearing for extreme portability.
f/4.2: $7,195
USD
f/3.7: $7,995
USD
f/3.3: $8,895
USD
Deposit (50% of base system)
Sandwich Mirror
GoTo Tracking
All Metal
Dual-Speed Focuser
Aperture
508mm (20")
Focal Ratio
f/3.3, f/3.7, or f/4.2
Mirror
Sandwich
Weight
~99 lbs
Exclusive Sandwich Mirror Technology
The lightweight sandwich mirror design cools dramatically faster than solid mirrors, minimizing thermal
gradients and eliminating a major source of image distortion. Unlike fan-based cooling, this passive
design achieves rapid and stable thermal equilibrium naturally — without introducing vibration.
Why this matters: One of the primary limitations in large-aperture telescopes is "mirror seeing" —
turbulence caused by temperature differences between the mirror and the surrounding air. In changing
conditions, a thick solid mirror may never fully reach equilibrium, preventing it from achieving its
full optical performance.
The sandwich mirror design minimizes this effect, allowing the system to reach optimal performance
quickly and consistently, delivering sharper and more stable views without the need for active cooling.
OnStep GoTo System
Built-in WiFi, Bluetooth, and Smart Hand Controller with 30,000+ objects. INDI and ASCOM driver support.
Compatible with SkySafari, Stellarium, KStars, and more. Telescope encoders for extra pointing and
tracking accuracy.
Enhanced Optical Coatings
96% enhanced reflective coatings on both primary and secondary mirrors with precision-controlled
dielectric layers. Maximum light throughput for bright, contrast-rich images on deep-sky targets.
All Metal Construction
CNC-machined 6063-T6 aluminum alloy truss tubes, structural steel mirror cell, and aluminum alloy OTA
and mount structure. Finished with environmentally friendly black powder coating.
Sharper images with almost 50% less coma than f/3.7 — a coma corrector is helpful but many people can live
without it. Smaller central obstruction (3.5" vs 4.0"). Easier to achieve perfect collimation.
Advantages of f/3.3 and f/3.7
No ladder needed for f/3.3 at all; f/4.2 may need a one-step ladder near zenith. Wider field of view —
even wider with f/3.3. A coma corrector is recommended for f/3.3.
All three focal ratios provide excellent views. With our unique two-section truss tubes for f/4.2 (one section
for f/3.3 and f/3.7), all are equally portable and strong. Please note that some counter weight will be required
for f/4.2 at the bottom (and for f/3.3 at the top), which is not provided.
Add these when ordering, or contact us at info@hubble-optics.com
View all 13 accessories
Carbon Fiber Truss Tubes
$800
Elegant, stronger, and lighter Carbon Fiber Truss Tubes.
12V Battery Holder
$30
A steel battery holder. Free shipping when ordered with the system.
Red Dot Finder Scope
$45
Light weight Red Dot Finder with brackets and dovetail. Simple, effective, and easy to adjust. Free
shipping with system.
8x50 Illuminated Finder Scope
$100
Top quality 50mm achromatic finder with dovetail bracket. Scale markings and adjustable red illumination.
+$25 shipping.
Truss Tube Grips
$7 each
0.9m cushioned vinyl foam grips — insulate, cushion vibration, and protect the truss tubes. Free shipping
with system.
Shroud
$120
Top quality Nylon/Lycra blend. Blocks stray light for better contrast. Free shipping with system.
Wheelbarrow Handle
$250
Stainless steel handles with two 6" pneumatic tires and ball bearings. Includes $100 shipping. Order with
system only.
Truss Tube Carry Bag
$60
Deluxe waterproof Nylon bag with draw-string cord. Free shipping with system.
5-Star Artificial Star
$22
Essential collimation tool. Free shipping when ordered with system.
Scope Storage Cover
$120
Polyurethane-coated nylon — light reflecting, water and dust resistant. Full protection in storage and in
the field. Free shipping with system.
Mirror Cover
$45
Strong plastic mirror cover. Free shipping with system.
Light Baffle
$50
Reduces stray light for improved contrast. Free shipping with system.
No fan needed — our sandwich mirror reaches thermal equilibrium without one.
There's a 50% deposit for the base system, and the full payment for the optional accessories at the order time.
The rest including shipping will be paid before the delivery (about 60 days after the deposit) via a PayPal
invoice.
UL20g will be shipped in 4 boxes: the main structure 1 & 2, the truss tubes, and the primary mirror.
Country
Regular (US$)
US
995
US (Hawaii)
1,062
Australia
965
Austria
894
Belgium
940
Brazil
2,950*
Canada
915
Chile
1,450
Denmark
850
France
875
Germany
860
Israel
Contact Us*
Italy
910
Japan
590
Korea, South
565
Lithuania
1,980
Mexico
1,065
Netherlands
795
New Zealand
920
Norway
845
Philippines
450
Poland
Contact Us*
Portugal
965
Romania
955
Russia
1,495
Singapore
476
South Africa
1,700
Spain
Contact Us*
Sweden
830
Switzerland
860
Taiwan
510
UK
890
* Shipped via FedEx, the exact cost depends on your specific address.
