A high-quality, large-aperture telescope optimized in a very light and compact package for extreme portability!
The Hubble Optics UL20 is a serious telescope for a serious observer, yet still easily transportable to dark sky locations by one person. The 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 any car.
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.
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!
There are two versions of the UL20: f/3.7 and 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.
- Smaller central obstruction
- Easier to achieve perfect collimation
Advantages of f/3.7:
- No ladder is needed for most people
- Wider field of view
Both f/3.7 and f/4.2 will provide you the excellent views. A coma corrector is required for the f/3.7.
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 provided.
- Exclusive Sandwich Mirror Technology: Hubble optics 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, California State Polytechnic University San Luis Obispo, for the US Army, and in 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. 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.
- Semi-Enhanced Optical Coatings: The 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.
- Engineered Mirror Support: The Dobson has an extensively modeled and optimized flotation system that provides more than adequate support for the sandwich mirror. The three-point 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.
- All Metal Construction: The 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.
- Linear Drive Crayford 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 eight times finer than the larger focus wheels. This fine adjustment allows for critical focusing during high power visual observing or for imaging applications.