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Hubble Optics Dobson telescope N 457/2058 UL18 f/4.5 Premium Ultra Light DOB


Quick Overview

The Hubble Optics Dobson telescope N 457/2058 UL18 f/4.5 Premium Ultra Light DOB is a lightweight construction ultraportable 18-inch telescope. The views through an instrument of this size are extremely impressive and the designers of this telescope have achieved an excellent balance between price, build quality and optics. A larger telescope such as this is not for the beginner, but the Hubble Optics UL18 will continue to deliver consistently breathtaking views for those who are up to the challenge of owning a telescope on this scale. To make finding and centering objects easier, an additional encoder "push to" kit is available, as is a light shroud - both are highly recommended.

Please note: this telescope is not kept in stock and normally has a lead time of 3-5 weeks for delivery.

Only 1 left

Availability: In stock



A high-quality, large-aperture telescope optimized in a very light and compact package for extreme portability!

The UL18 is a telescope big enough to give satisfying views for a serious observer, yet still easily transportable to dark sky locations by one person. The Hubble Optics UL18 not only delivers the premium optical experience you need to seriously explore our universe, but tipping the scales at only about 72 lbs it's one third of the weight of classical Dobsonian telescope and folded into a compact package that will fit in any car.

The UL18 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 UL18 has a parabolic primary with a full 18-inch diameter of optical surface, a generous 18.4” overall diameter; not an 18-inch blank with a beveled and much smaller optical surface, which is about 5% more optical surface and light gathering than any other 18” scopes in the market. In addition, with its fast focal ratio mirror, the Hubble UL18 telescope has an eyepiece location that can almost always be reached when you are standing with both feet on the ground (only 68" from the ground when the UL18 is pointed at zenith).

The Hubble UL18 is a telescope that can provide a lifetime of satisfying observing experiences in a 72-pound package!

There are two versions of the UL18: f/4 and f/4.5

Advantages of f/4.5:

  • Sharper images. No need for a coma corrector at all.

  • Smaller central obstruction

  • Easier to achieve perfect collimation



Advantages of f/4:

  • No ladder is needed for most people; while you may need one-step ladder for an f/4.5 when close to zenith direction.

  • Wider field of view



Both f/4 and f/4.5 will provide you the excellent views. The f/4.5 provides the perfect view for the most demanding observer, without coma corrector. A coma corrector is strongly recommended for the UL18 f/4.

Please note that some counter weight will be required for f/4.5 at the bottom, which is NOT provided.

Some Features:

  • 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

    Type Reflector
    Type of build Newton
    Aperture (mm) 457
    Focal length (mm) 2058
    Aperture ratio (f/) 4.5
    Resolving capacity 0.25
    Limit value (mag) 15.1
    Light gathering capacity 4260
    Max. useful magnification 914
    Tube construction Truss Tube
    Tube material Aluminium
    Tube weight (kg) 28
    Main mirror´s construction parabolic
    finish quality 1/10
    Secondary mirror diameter (mm) 70
    Secondary mirror obstruction 19.7
    reflectivity 96
    Adjustable yes
    Ventilation for central mirror no
    Primary mirror - Material Pyrex glass
    Type of build Crayford
    Gear reduction 1:10 Fine movement
    Connection ( to eyepiece) 2
    Adjustment range (mm) 50
    Mounting type Dobson
    GoTo control no
    Included accessories
    1.25'' eyepieces without
    2'' eyepieces without
    Finder scope Red dot finder
    Total weight (kg) 32
    Eyepiece height at zenith (mm) 1930
    Series Ultra Light
    Area of application
    Astrophotography not recommended
    Moon & Planets yes
    Nature Observation no
    Nebulae & galaxies yes
    Sun no
    recommended for
    Beginners no
    Advanced yes
    Observatories no



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