Hubble UL18 – A Lightweight 18" Dobsonian Telescope
The Hubble UL18 is a made-to-order 18-inch Dobsonian telescope, built specifically for serious visual observers who want true observatory-class performance in a portable, transportable design.
With a massive 18-inch primary mirror, the UL18 gathers over five times more light than an 8-inch telescope, and more than twice the light grasp of a 12-inch, unlocking faint galaxies, delicate nebular structure, and extreme planetary detail that simply isn’t possible with smaller apertures.
Light, Strong, and Surprisingly Portable
Each UL18 is custom built to order using precision-machined all-metal components. The truss construction uses eight rigid aluminium truss tubes and a folding altitude bearing structure to provide exceptional stiffness while keeping overall weight under control.
The large mirror box design protects the primary mirror during transport, while the modular layout allows the telescope to be broken down quickly for storage or travel. Fully assembled, the UL18 weighs just ~33 kg, making it one of the most portable 18-inch class Dobsonians available.
Optical Performance
At the heart of the UL18 is a premium parabolic primary mirror, individually tested and finished to achieve diffraction-limited performance (Strehl 0.95+). The secondary mirror is specified to 1/10 wave or better, ensuring excellent contrast and pinpoint stellar images across the field.
Both mirrors receive 96% enhanced reflective coatings, maximising light throughput while reducing scatter. This results in brighter deep-sky views, improved low-contrast detail, and excellent planetary performance even at extreme magnifications.
Choose Your Telescope Control
The UL18 can be customised to suit your observing style. You can use it fully manually, or opt for Guided Push-To or Automatic Go-To systems.
Manual Mode
Even without electronics, the UL18 is a precision Dobsonian with smooth, stable bearings and an easy-to-use truss design. You can enjoy the classic hands-on experience, exploring the night sky exactly as the great visual observers have for decades.
Guided Push-To Version
The UL18 Guided Push-To version features the SkyHub2 digital setting circle system, providing accurate real-time telescope positioning without motorised tracking. High-resolution 8192 PPR encoders on both axes continuously update your telescope’s position in compatible planetarium software.
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Alignment is fast and intuitive using a simple one-star alignment, with optional two-star alignment for increased accuracy.
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Works with SkySafari, Stellarium, Cartes du Ciel, TheSky, and other ASCOM-compatible software on Windows, macOS, Android, and iOS devices.
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Extremely low power consumption: up to 100 hours from a 15,000 mAh USB power bank.
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WiFi and Bluetooth supported (WiFi only for iOS devices).
Automatic Go-To Version
The UL18 Go-To version adds fully motorised pointing and tracking for a completely hands-free observing experience. It includes a smart hand controller with a 30,000-object database and supports advanced 1–9 star alignment for precise pointing accuracy.
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Built-in encoders and a real-time clock maintain accurate sidereal, lunar, and solar tracking rates.
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Control via WiFi or Bluetooth using SkySafari, Stellarium, or ASCOM/INDI-compatible software on Windows, macOS, Linux, iOS, or Android.
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Adjustable slew and guide speeds, spiral search, and park/unpark functionality provide smooth, precise movement for extended observing sessions.
Choosing Your Focal Ratio: f/4.0 or f/4.5
The UL18 is available in f/4.0 or f/4.5, allowing you to prioritise either maximum comfort or maximum optical refinement.
Why choose f/4.0?
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Lower eyepiece height – no ladder required for most users
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More compact overall system
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Wider true field of view
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Ideal for observers who value comfort and portability
Why choose f/4.5?
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Reduced coma across the field
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Slightly smaller secondary obstruction
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Better suited to high-power planetary and lunar observing
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Preferred by observers seeking ultimate optical purity
Both versions deliver extraordinary performance. The f/4.0 favours ergonomic comfort and wide-field observing, while the f/4.5 favours optical cleanliness and contrast. The choice ultimately comes down to observing style and personal preference.
Specifications (UL18)
| Optical design | Reflector |
|---|---|
| Optical diameter | 18" (457.2 mm) |
| Focal length | ~1860 mm (f/4.0) ~2058 mm (f/4.5) |
| Focal ratio | f/4.0, f/4.5 |
| Eyepiece height at zenith | ~1730 mm (f/4.0) ~1930 mm (f/4.5) |
| Optics type | Parabolic |
| Eyepieces | Not included |
| Optical quality | Diffraction limited++ (Strehl 0.95+ primary 1/10 λ PV secondary) |
| Finder scope | Not included |
| Focuser | 2" dual-speed linear bearing Crayford (50.8 mm) |
| Secondary mirror | 90 mm (f/4.0), 80 mm (f/4.5) |
| Secondary mirror obstruction by diameter | 19.7% (f/4.0), 17.2% (f/4.5) |
| Secondary mirror obstruction by area | 3.9% (f/4.0), 3.0% (f/4.5) |
| Mirror coatings / over-coatings | 96% Enhanced coating on primary and secondary mirrors |
| Tube material | 6063-T6 Aluminium Alloy tubes with black zinc-plated steel knob screws aluminium alloy main structure (OTA and mount) and steel mirror cell |
| Length of optical tube | ~1830 mm (f/4.0) ~2010 mm (f/4.5) |
| Weight, optical tube | ~28 kg |
| Weight, fully assembled | ~33 kg |
| Dawes Limit | 0.25″ |
| Rayleigh Limit | 0.30″ |
| Limiting Magnitude | 15.8 |
| Maximum Magnification | 900× |
| Additional / optional accessories | 8×50 Finder Tube Shroud Wheelbarrow handles Vinyl foam cushioned grips |
| Other features | Sling lateral support and deluxe push-pull brass knob collimation screws |
