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, 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. Our sandwich mirror will reach thermal equilibrium up to 10 times faster than a traditional solid 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.

Enhanced Optical Coatings:

The Hubble UL20 primary mirror and the secondary mirror are coated with the state of the art 96% 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 96% Enhanced coating has multiple over-coating of precision controlled dielectric layers to maximize the reflectivity and provide excellent chemical and mechanical protection for the mirror coating.

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.

UL20 Specs

• Optical diameter:508mm
• Focal length : ~1676mm (f/3.3), ~1880mm (f/3.7), ~2134mm (f/4.2)
• Eyepiece height at zenith: ~1490mm(~59 in, f/3.3), 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 lambda or better in PV for the secondary mirror)
• Finder scope: Not included
• Focuser: 2" dual-speed linear bearing Crayford
• Secondary mirror obstruction: 100 mm (f/3.3, f/3.7), 90mm (f/4.2)
• Secondary mirror obstruction by diameter: 19.7% (f/3.3, f/3.7), 17.7 (f/4.2)
• Secondary mirror obstruction by area: 3.9% (f/3.3, f/3.7), 3.1% (f/4.2)
• Mirror coatings/over-coatings: 96% Enhanced coating on both of the primary and secondary mirrors
• Tube material: 6063-T6 Aluminum Alloy tubes with black zinc plated steel knob screws; Aluminum Alloy main structure (OTA and mount) and structure steel mirror cell.
• Length of optical tube : 73 in (f/3.3, f/3.7), 83 in (f/4.2)
• Weight, optical tube : 76 lbs (f/3.3,f/3.7), 77 lbs (f/4.2)
• Weight, fully assembled : ~88 lbs. (f/3.3, f/3.7), ~89 lbs (f/4.2)
• Dawes Limit(arcsec): 0.19
• Rayleigh Limit(arcsec): 0.23
• Limiting Mag: 16.4
• Maximum Magnification: 1200
• Additional, optional accessories: 8x50 Finder, Shroud, Wheelbarrow, Vinyl foam Cushioned Grips
• Other features: Sling lateral support and deluxe push-pull brass knob collimation screws