Sandwich primary mirror
The ventilated sandwich design promotes cooling. A mirror close to ambient temperature reduces one source of image-softening air currents.
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Hubble Optics
Hubble Optics UL18 18 Inch Premium Ultra Light Dobsonian Telescope
$8,090.00
18-inch aperture with a choice of observing height.
The Hubble Optics UL18 is a 457.2 mm parabolic reflector for experienced visual observers. Its open truss and separate mirror box make a large telescope easier to break down, while two focal ratios give you a useful choice of eyepiece height.
A mirror box and removable trusses for large aperture observing.
The UL18 separates into an upper assembly, truss tubes and lower mirror-box structure. That makes it easier to pack for a dark-sky trip, while keeping the primary mirror in its support system. Allow time to reassemble and check collimation at the observing site.
Manual telescope pictured. Control hardware depends on the selected Telescope Control option; finder is optional.
How the UL18 supports and focuses the image.
18-point mirror support
The flotation cell distributes the rear support of the primary mirror. Lateral support and collimation are separate, so alignment does not rely on distorting the mirror edge.
Dual-speed focusing
The 2-inch linear-bearing Crayford focuser gives you coarse adjustment followed by fine focus. Eyepieces are selected separately to suit the targets and magnifications you use.
Choose how you find and follow objects.
Manual
Locate targets yourself and move the telescope by hand.
- PointingBy hand
- Following an objectBy hand
Guided Push-To
Digital position guidance helps you locate a target; you still move the telescope yourself. Push-To does not add motorised tracking.
- PointingGuided, moved by hand
- Following an objectBy hand
Automatic Go-To
After setup and alignment, the drive moves to selected objects and follows them as the sky turns. A suitable power source is required.
- PointingMotorised
- Following an objectMotorised
These are separate Telescope Control choices. Compatible hardware and software are required for phone or tablet control. Power requirements depend on the supplied control system.
Choose focal ratio for your observing position.
The lower focal-ratio option places the eyepiece lower. The higher focal-ratio option uses a smaller secondary mirror. Each focal ratio is available with all three Telescope Control choices.
f/4.5
- Eyepiece at zenithapproximately 1930 mm
- Secondary diameter80 mm
f/4.0
- Eyepiece at zenithapproximately 1730 mm
- Secondary diameter90 mm
Eyepiece heights are approximate, with the telescope pointing straight up. Your height and observing position determine whether a step is needed.
Plan the space and handling.
Assembled weight, Manualapproximately 32.7 kg (72 lb)
Eyepiece height at zenithf/4.5: approximately 1930 mm; f/4.0: approximately 1730 mm
Manual telescope figures exclude added control equipment and observing accessories. Plan carrying, storage and eyepiece access for your chosen configuration.
Good to know.
Choose eyepieces and finder separately
Eyepieces and a conventional optical finder are not included. Shrouds and other light-control accessories are separate options.
Check collimation after assembly
Collimation aligns the mirrors. Check it after reassembly and before observing. UL18 assembly and setup manual.
Allow for balance weights
The f/4.5 configuration can require additional counterweight at the lower end. Counterweights are not included.
Keep this telescope away from the Sun
Never point the telescope or finder at the Sun without the correct purpose-made solar protection. Unfiltered viewing can cause permanent eye damage.
Specifications.
Optics
Optical Design
Reflector
Optical Diameter
457.2mm
Focal Ratio
f/4.0, f/4.5
Eyepiece Height at Zenith
f/4.5: approximately 1930 mm; f/4.0: approximately 1730 mm
Optics Type
Parabolic
Optical Quality
Diffraction limited (Strehl 0.95+, 1/10 wave PV secondary)
Focuser
2" dual-speed linear bearing Crayford
Mirror Coatings
96% Enhanced on both primary and secondary
Secondary mirror diameter
f/4.5: 80 mm; f/4.0: 90 mm
Structure and controls
Tube Material
6063-T6 Aluminium Alloy, structural steel mirror cell
Optical Tube Length
~72" (f/4.0), ~79" (f/4.5)
Mirror support
18-point flotation cell
Assembled weight (Manual)
approximately 32.7 kg (72 lb)
Eyepieces
Not included
Conventional finder scope
Not included
Telescope Control
Manual; Guided Push-To; Automatic Go-To
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18-inch aperture with a choice of observing height.
The Hubble Optics UL18 is a 457.2 mm parabolic reflector for experienced visual observers. Its open truss and separate mirror box make a large telescope easier to break down, while two focal ratios give you a useful choice of eyepiece height.
A mirror box and removable trusses for large aperture observing.
The UL18 separates into an upper assembly, truss tubes and lower mirror-box structure. That makes it easier to pack for a dark-sky trip, while keeping the primary mirror in its support system. Allow time to reassemble and check collimation at the observing site.
Manual telescope pictured. Control hardware depends on the selected Telescope Control option; finder is optional.
How the UL18 supports and focuses the image.
Sandwich primary mirror
The ventilated sandwich design promotes cooling. A mirror close to ambient temperature reduces one source of image-softening air currents.
18-point mirror support
The flotation cell distributes the rear support of the primary mirror. Lateral support and collimation are separate, so alignment does not rely on distorting the mirror edge.
Dual-speed focusing
The 2-inch linear-bearing Crayford focuser gives you coarse adjustment followed by fine focus. Eyepieces are selected separately to suit the targets and magnifications you use.
Choose how you find and follow objects.
Manual
Locate targets yourself and move the telescope by hand.
- PointingBy hand
- Following an objectBy hand
Guided Push-To
Digital position guidance helps you locate a target; you still move the telescope yourself. Push-To does not add motorised tracking.
- PointingGuided, moved by hand
- Following an objectBy hand
Automatic Go-To
After setup and alignment, the drive moves to selected objects and follows them as the sky turns. A suitable power source is required.
- PointingMotorised
- Following an objectMotorised
These are separate Telescope Control choices. Compatible hardware and software are required for phone or tablet control. Power requirements depend on the supplied control system.
Choose focal ratio for your observing position.
The lower focal-ratio option places the eyepiece lower. The higher focal-ratio option uses a smaller secondary mirror. Each focal ratio is available with all three Telescope Control choices.
f/4.5
- Eyepiece at zenithapproximately 1930 mm
- Secondary diameter80 mm
f/4.0
- Eyepiece at zenithapproximately 1730 mm
- Secondary diameter90 mm
Eyepiece heights are approximate, with the telescope pointing straight up. Your height and observing position determine whether a step is needed.
Plan the space and handling.
Assembled weight, Manualapproximately 32.7 kg (72 lb)
Eyepiece height at zenithf/4.5: approximately 1930 mm; f/4.0: approximately 1730 mm
Manual telescope figures exclude added control equipment and observing accessories. Plan carrying, storage and eyepiece access for your chosen configuration.
Good to know.
Choose eyepieces and finder separately
Eyepieces and a conventional optical finder are not included. Shrouds and other light-control accessories are separate options.
Check collimation after assembly
Collimation aligns the mirrors. Check it after reassembly and before observing. UL18 assembly and setup manual.
Allow for balance weights
The f/4.5 configuration can require additional counterweight at the lower end. Counterweights are not included.
Keep this telescope away from the Sun
Never point the telescope or finder at the Sun without the correct purpose-made solar protection. Unfiltered viewing can cause permanent eye damage.
Specifications.
Optics
Optical Design
Reflector
Optical Diameter
457.2mm
Focal Ratio
f/4.0, f/4.5
Eyepiece Height at Zenith
f/4.5: approximately 1930 mm; f/4.0: approximately 1730 mm
Optics Type
Parabolic
Optical Quality
Diffraction limited (Strehl 0.95+, 1/10 wave PV secondary)
Focuser
2" dual-speed linear bearing Crayford
Mirror Coatings
96% Enhanced on both primary and secondary
Secondary mirror diameter
f/4.5: 80 mm; f/4.0: 90 mm
Structure and controls
Tube Material
6063-T6 Aluminium Alloy, structural steel mirror cell
Optical Tube Length
~72" (f/4.0), ~79" (f/4.5)
Mirror support
18-point flotation cell
Assembled weight (Manual)
approximately 32.7 kg (72 lb)
Eyepieces
Not included
Conventional finder scope
Not included
Telescope Control
Manual; Guided Push-To; Automatic Go-To
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