* Shipped via Fedex/DHL, the exact cost depends on your specific
- A quantum leap in optical performance - the UL 20 Truss Dobsonian
telescope's huge 20" diameter primary mirror gathers more than 6
times more light than popular 8" reflectors or almost three times of the
light grasp of a 12" telescope
- A Premium, Light, Compact and Portable Design - About half the
weight of traditional Dobsonian telescopes.
- Outstanding Images - Premium quality, diffraction limited Newtonian
optical systems will deliver stunning views of the heavens from dark
- Light, Strong, Compact and Extremely Portable - The Hubble UL20
features a precision-machined all-metal construction. Fully assembled
the UL20 weighs at about 90 pounds. It has 8 rigid truss tubes and
extremely strong and portable folding ALT bearing structure. It
features a real mirror box for safe mirror protection, and convenient
storage and transportation
- Exclusive Optical Technology - The UL20 features Hubble lightweight
sandwich mirror with an optimized thermal design that cools up to 10
times faster than the regular solid mirrors
- Fast Optics - The UL20 fast optical system delivers bright images and
features a short tube keeping the eyepiece conveniently close to the
- Semi-Enhanced Coating on the Primary Mirror - The most
recommended (by professionals) 92% Semi-Enhanced Coating on the
primary mirror and 96% Enhanced coating on the secondary mirror.
- Modular and Compact Design: The Hubble UL20 is delivered in
several preassembled modules. The entire systems can be
assembled easily and quickly, as little as a few minutes.
20" Premium Ultra Light Dobsonian
8 x 50 Straight Through Illuminated Finder Scope with Brackets and
A top quality 50mm achromatic finder offering an inverted and reversed
image, perfect for Newtonian Telescope. A deluxe quick release double-ring
Finder Bracket including a dovetail base is included. There will be $15
additional charge for the surface delivery, or $25 additional charge the air
The scale markings and open center of the 8 X 50 Straight-Thru Finder
allows you to measure distances and easily center an object in the field of
view. The brightness of the reticle can be adjusted, which is nice when you
are searching for fainter objects.
The illuminator screws into the end of the finder and can be removed easily to
change batteries. The deep red illumination can be adjusted for brightness.
Truss Tube Grips
0.9m (35.5"), slid-on round cushioned grips, made of vinyl foam, they
insulate, cushion vibration and protect the truss tubes. Free shipping when
ordered with system.
$120 + S&H
The strong stainless steel handles, two top quality 6" pneumatic tires with ball
bearing. The shipping cost will be $70 for the surface delivery and $100 for
the air delivery, for US. The shipping cost might be different for other
$90 (f/3.7), $100 (f/4.2)
Made from the top quality Nylon/Lycra blended materials, it is one of the
options you would really like to have.
Free shipping when ordered with the system.
Truss Tube Carry Bag
$50 (f/3.7), $60 (f/4.2)
Made from the deluxe waterproof Nylon material with draw-string cord.
Free shipping when ordered with the system.
5-Star Artificial Star
$19.95 (free shipping if ordered with system)
It is really the time to have one, if you still don't have one yet!
Sorry, but It is not an option for UL20. You simply do not need one for our
Scope Storage Cover
$100 (free shipping when ordered with the system)
Made with nice and strong polyurethane coated nylon fabric; light reflecting,
water and dust resistant. A complete protection for your scope not only in the
storage but also in the field.
$50 (free shipping when ordered with the system)
A very nice and strong plastic mirror cover
Hubble SkyHub Wireless Digital Setting Circle System
$199 (Special offer when ordered with UL20 f/3.7)
Breakthrough Wireless Digital Setting Circle with revolutionary high
resolution, low power consumption ball bearing encoders at an inconceivable
More info here
Hubble SiTech and SkySafari based GOTO system
Special offer at $1995 only!
Simply the most powerful and feature rich GOTO system at an extremely
More info here
Which UL20, f/3.7 or f/4.2?
Advantages of f/4.2:
- Sharper images. It has almost 50% less coma than UL20 f/3.7; a coma
corrector will still be helpful, but many people may live without it.
- With the special introduction offer, you save $1,300 over UL f/3.7!
- Smaller central obstruction, 3.5” (f/4.2) v.s. 4.0” (f/3.7) secondary mirror
- Easier to achieve perfect collimation
Advantages of f/3.7:
- No ladder is needed for most people; while you may need one-step
ladder for an f/5 when close to zenith direction.
- Wider FOV.
Both f/3.7 and f/4.2 will provide you the excellent views. A coma corrector is
required for the UL20 f/3.7.
With our unique two-section truss tubes for f/4.2 (one section truss for f/3.7),
f/4.2 is just as portable and strong as f/3.7. At the end, it is really your
Please note that some counter weight (real and/or a virtual spring
counter weight) will be required for f/4.2 at the bottom, which is NOT
The Hubble UL20 Premium Dobsonian telescope is optimized to offer you
high-quality, large-aperture telescopes designed in a very light and compact
package for extreme portability. With a Hubble UL20, you are free to travel to
your favorite dark-sky sites anywhere in the world.
Why should you select a Hubble UL20?
UL20 is a serious telescope for a serious observer, yet still easily transportable
to dark sky locations by one person. The Hubble UL20 not only delivers the
premium optical experience you need to seriously explore our universe, but
tipping the scales at only about 90 lbs it's one third of the weight of classical
Dobsonian telescope and folded into a compact package that will fit in almost
The UL20 is a perfect balance between a telescope with huge light-gathering
capability and unbeatable portability. It will be the telescope that gets taken
out of the garage or from the back of a car to be used frequently. It will provide
stunning views of the heavens and a lifetime of observing enjoyment.
The UL20 has a parabolic primary with a full 20-inch diameter of optical
surface, a generous 20.4” overall diameter; not an 20-inch blank with a
beveled and much smaller optical surface, which is about 4% more optical
surface and light gathering than any other 20” scopes in the market.
Hubble UL series has been designed to be as light and compact as possible,
making the task of transport to your favorite dark-sky site as easy as possible.
The heaviest component of the UL20 is the primary mirror, which weighs in at
about 38 pounds, and the entire telescope is only about 90 pounds, which is
remarkably light for a 20-inch telescope. In addition, with its fast focal ratio
mirror, the Hubble UL20 telescope has an eyepiece location that can almost
always be reached when you are standing with both feet on the ground (only
69" from the ground when the UL20 is pointed at zenith).
With the Hubble UL20, the view will be simply spectacular all over the sky. The
Hubble UL20 is a telescope that can provide a lifetime of satisfying observing
experiences in a 90-pound package!
Features of the UL20:
Exclusive Sandwich Mirror Technology: Our sandwich mirror technology
has been used to manufacture research-grade optical elements and proven
by over a half dozen years of successful applications at research facilities
such as NASA, Princeton University, California State Polytechnic University
San Luis Obispo, the US Army, and in professional and amateur telescopes
around the world. Hubble sandwich mirror’s open core and close back design
not only allows air to circulate through the mirror, but also provide the
maximum structure strength to allow a simpler mirror cell design. Our
sandwich mirror will reach thermal equilibrium up to 10 times faster than a
traditional solid 20-inch mirror and means the mirror can deliver great views
even as the air around the telescope is changing temperature.
Why is thermal equilibrium so critical? The main issue is "mirror seeing," the
turbulence seen through the eyepiece of the telescope when the air above the
mirror is different from the mirror itself. Since a sandwich mirror cools far more
rapidly than a solid mirror of the same thickness, this major source of
distortion is eliminated quickly, giving you sharp and stable views. With ever-
changing temperatures during observing or imaging, your thick and solid
mirror may never reach equilibrium, and never reach its full optical potential.
This is one of the major reasons why our lightweight-sandwich mirror has
superior optical performance in real world situations, even without an active
cooling system. (Active cooling systems, such as fans, introduce their own
problems, such as micro vibration, which may seriously degrade the image
quality.) Our sandwich mirrors reach equilibrium extremely fast, and without
any external disturbing aid.
Semi-Enhanced Optical Coatings: The Hubble UL20 primary mirror is
coated with the most recommended (by professionals) 92% Semi-Enhanced
optical coatings to assure it collects as many (while scattering as little) photons
as possible to focus it into a bright and contrast-rich image. The optimal 92%
Semi-enhanced coating has an over-coating of precision controlled dielectric
layer to maximize the reflectivity and provide excellent chemical and
mechanical protection for the mirror coating. A 96% enhanced optical coating
is applied on the secondary mirror.
A Real Mirror Cell In A Real Mirror Box: : The UL20 has an extensively
modeled and optimized 18-point flotation system that provides more than
adequate support for the sandwich mirror. The three-point Push-Pull
collimation system is completely independent from the sling lateral support. It
will totally eliminate the often-found potato chip astigmatism introduced by
sling belt when using the simple 3 pivoted bolts collimation system. In a simple
pivoted bolts collimation system, the collimation of the primary mirror may
cause the sling belt to pull the mirror axially on the mirror edge, bending the
mirror to a potato-chip shape, causing annoying astigmatism. It also comes
with a real mirror box for easy and safe mirror protection and transportation.
All Metal Construction: The UL20 mechanical structures have been
extensively modeled via 3D CAD and advanced FEA to provide the optimal
structure strength and stability. Machined with Computer Numerical Control
(CNC) technology and hand fitted to assure proper fit and finish. Super strong
T6063-T3 aluminum alloy truss tubes, structure steel mirror cell and aluminum
alloy OTA and mount structure. Completed with deluxe and environmentally
friendly black powder coating, it is such a pleasure to look at, not to mention
the enjoyment to look through.
Dual-Speed 2-inch Linear Drive Crayford Focuser: The Hubble UL20
comes with a precision dual-speed, 2-inch diameter focuser. It's a beautiful
piece of precision machining that enhances the viewing experience as well as
the overall impression of a premium quality instrument you'll have with this
telescope. This focuser is robust! It is a zero-backlash "Crayford-style" design
further enhanced with modern "linear bearings" meaning you get a rock-solid,
super smooth focusing experience that can handle the weight of even the
heaviest of modern eyepieces. Its tension, the pressure on the drawtube, is
preset to a very reasonable level, but adjustable to lock heavy equipment in
place if desired. The smaller stainless steel focus control adjusts focus at a
rate 8 times finer than the larger focus wheels. This fine adjustment allows for
critical focusing during high power visual observing or for imaging applications.
The focuser has 50mm of travel distance.
- Optical design : Reflector
- Optical diameter : 508mm
- Focal length : ~1880mm (f/3.7), ~2134mm (f/4.2)
- Eyepiece height at zenith: 1745mm (~69 in, f/3.7), 2000mm (~79 in, f/4.2)
- Optics type : Parabolic
- Eyepieces: Not included
- Optical quality : Diffraction limited++ (Strehl 0.95+ for the primary mirror,
1/10 lambada or better for the secondary mirror)
- Finder scope : Not included
- Focuser : 2" dual-speed linear bearing Crayford
- Secondary mirror obstruction : 100 mm (f/3.7), 90mm (f/4.2)
- Secondary mirror obstruction by diameter : 19.7% (f/3.7), 17.7 (f/4.2)
- Secondary mirror obstruction by area : 3.9% (f/3.7), 3.1% (f/4.2)
- Mirror coatings/over-coatings : 92% Semi-Enhanced Aluminum coating
on the primary and 96% Enhanced coating on the secondary mirror
- Tube material : 6063-T6 Aluminum Alloy tubes with black stainless steel
knob screws; Aluminum Alloy main structure (OTA and mount) and
structure steel mirror cell.
- Length of optical tube : 73 in (f/3.7), 83 in (f/4.2)
- Weight, optical tube : 76 lbs (f/3.7), 77 lbs (f/4.2)
- Weight, fully assembled : ~88 lbs. (f/3.7), ~89 lbs (f/4.2)
- Additional, optional accessories : 8x50 Finder, Shroud, Wheelbarrow,
Vinyl foam Cushioned Grips
- Other features : Sling lateral support and deluxe push-pull brass knob
Shipping and Handling:
A real benefit of a our Ultra Light, Ultra Compact and Ultra Portable UL20 to
you, a very reasonable worldwide shipping cost (at least for most of the
countries) for the total system. Please understand the surface shipping is a
great value, but may take more than additional 10 weeks for the delivery.
UL20 will be shipped in 6 boxes: the main structure 1 & 2, the truss tubes 1
& 2, the accessories and the primary mirror.
All units will be shipped from Hong Kong!
$2797.50 (f/3.7), $2397.5 (f/4.2) deposit
at the order time, rest, including options
and shipping will be paid before the
delivery (about 60-90 days after the
deposit) via a Paypal invoice.
Please note that the above 60-90 days
delivery is the estimated production lead
time only, which does not include
shipping transit time.
Please specify your requested options in
your payment for the deposit.
UL 20 f/3.7
UL 20 f/4.2