| NOTE: THIS ITEM CANNOT BE SHIPPED STORE PICKUP ONLY SELECT PICK UP AT CHECKOUT |
Yes, our inventory is accurate!
SHIPPING NOT AVAILABLE - In Store Only
Condition: This is a LOADED 18" Obsession Dobsonian from about 2015 in very good condition. You've heard of the quality that is an Obsession scope, now come see it for yourself. This is over FIFTEEN THOUSAND DOLLARS worth of equipment for under FIVE THOUSAND BUCKS.
The mirror is in good shape, but it is definitely dusty. See the photos, where we've tried to capture this - the dust you see in different areas of the mirror is consistent across basically the entire surface of the mirror. In addition to the general dust, there are a couple of small spots on the edge of the mirror surface. One of these spots is where masking tape contacted the mirror. You may be able to clean this off yourself with something like GooGone, or more to the point, its optical equivalent. (We have no idea if GooGone itself will actually work or will be worse for the optics.) You will definitely want to give the mirror a good and thorough cleaning after purchase.
Alternatively, the previous owner is willing to split the costs of resurfacing the mirror with you, up to $650. Ostahowskioptiocs.com in Anza, Calif. (760-445-3398) is quoting $649 for stripping and recoating an 18-inch mirror. You would be responsible for packing and shipping both ways. Please contact us with any questions about that.
The scope is in mechanically excellent condition - everything works. It includes an upgraded Feathertouch Focuser. This scope includes both the Nexus and Argo Navis digital setting circles as well as the ServoCAT goto drive/tracking system. It is set up with the Nexus system, but includes the Argo Navis separately as well. We've tested the Nexus DSC system and the encoders are working. We've tested the ServoCAT system and the motors work to move the telescope in all four directions.
It also includes a huge amount of upgrades. a ripstop light shroud for the tube, two power sources, a Barlowed laser collimator, a dew heater for the secondary mirror, as well as light shields for the primary mirror at the bottom of the tube, and for the secondary mirror at the top of the tube.
You will need to make sure that you can handle a scope of this size and complexity: it is over 6 feet tall, and you will need to work with connecting all the plugs and the cabling to make sure everything is functioning as it should. While we can't really assist you much with this, as we don't know how everything works together, the previous owner is available and has volunteered to give you some advice about disassembling and reassembling. We do have both the original manuals and the previous owner has prepared cheat sheets to assist you in this regard.
The scope packs away in a large hard-shelled case, included.
Here's everything that's included - and it is loaded:
- Obsession 18” f4.2 UC (Ultra compact) OMI Primary and Astrosystems secondary
- ServoCat GOTO drive upgraded with Nexus DSC Pro (digital setting circles), powered ground board system installed and with ServoCat Hand controller (a $3495 upgrade). Scope is set up for three means of control:
- (1) using SkySafari as the Planetarium software for control and GOTO;
- (2) scope can also be used as PUSH/TO or
- (3) controlled by ServoCat Hand controller
- Feathertouch focuser with curved rotatable base, compression rings and feather touch 1.25” to 2.0” eyepiece adapter (a $650 upgrade)
- Markless Astronomy digital setting circle (DSC) mounting stalk
- Nexus DSC (digital setting circles)
- Pegasus Astro Pocket Powerbox Micro for powering dew heaters, cameras (a $107 upgrade)
- Argo Navis DSC (not installed) (an $895 upgrade)
- Dew heater for secondary (an $85 upgrade)
- Telrad finder (a $45 upgrade)
- Astromania Cheshire collimator (long version)
- Astrosystems Laser Colllimator with Barlow attachment (a $195 upgrade)
- Apertura universal 10 Amp AC Adapter/power supply (a $120 upgrade)
- Pyramid PS-9KK Regulated 12 volt Power supply
- 12 volt cooling fan for primary
- Side bearing stabilizer bars
- 10K encoders and encoder arm assembly
- Robinson Jig
- Counterweight kit
- Ripstop Nylon Light shroud (with 2 fiber glass support sticks) (a $219 upgrade)
- Upper and lower light baffles
- Astrosystems Telescope cover for 18 UC scope
- Astrosystems Truss Tube carry case
- Wheel barrow handles for scope with 10 inch pneumatic wheels
- White travel/foam-lined storage case for 18 UC scope
- Quick start Instructions and original manuals.
That's over $5800 in upgrades - and the entire scope is only $4500!
Also included is an old Mallincam system.
NO WARRANTY, GUARANTEE, OR RETURNS ON THIS ITEM. BUYER TO INSPECT PRIOR TO PURCHASE.
This is only available for in-store pickup.
Just your size. Large Aperture, no big ladder needed!
The Obsession 18" UC is the ultimate compact scope for the discriminating enthusiast who wants big aperture in a small package.
There are no short cuts in construction or performance.
The Obsession 18" UC features the same quality craftsmanship and award winning design as found on our renown 20, 25, 30 and 36 inch telescopes.
We've done our homework - the 18" is easy to set up and a joy to use.
Fantastic deep sky and planetary images.
One look and you'll re-learn what it means to be excited about astronomy.
| 5 times the light gathering power of an 8 inch Schmidt-Cassegrain | Obsession 18" UC |
Typical 8" |
|---|---|---|
| Limiting stellar magnitude: | 16 | 14.0 |
| Rayleigh Resolution Limit: | 0.31 arc seconds |
0.68 arc seconds |
| Contrast limit: (minimum diameter before a nebular object fades from view) |
4.8 arc minutes |
11.0 arc minutes |
18" Specifications:
Metric info shown in italics
Primary Mirror:
- 18" - 457 mm OMI 2 inch thick mirror
- Fused silica glass standard on all 18" Classic primary mirrors.
- 96% reflectivity
- Enhanced Aluminum Coating and Dielectric Overcoat (a supreme coating)
- Center marked for precise collimation
- plus Interferometry certification
see Optics page for more info
Secondary Mirror:
- Pre-installed
- 3.1" - 79 mm United Lens 1/10 wave or better
- Interferogram included
- 96% reflectivity at 550 nm
- Super enhanced Brilliant-Diamond non-fading multi-dielectric coating
see Optics page for more info
The 18" f/4 UC (Ultra Compact) is a revolutionary design. It is a large aperture telescope that collapses into a very small package. If you have limited hauling or storage capacity, (like the trunk of a small car) then this is the scope for you.
Our revolutionary Virtual Mirror Box (VMB) is the foundation of the UC design. It is a welded steel framework made from NC laser cut steel. It provides four main functions. It provides the primary mirror cell, the altitude bearings, the connection points for the truss poles, and a retainer for the wheelbarrow handles. To keep it as ultra compact as possible, the side bearing portion is foldable to reduce the height of the VMB by half.
In the transport mode the clearance height is a mere 14 inches. Or place the VMB (Virtual Mirror Box) next to the rocker in your car and reduce the height even more. Now everyone can have a big aperture scope and take it to their dark sky site. This telescope will appeal to those that like the ultimate in form follows function style. Lower eyepiece height means 90% of observing will be done with your feet on the ground. The UC is all black with a modern space frame construction. If your vehicle is small or you intend to put it in the trunk, then the Ultra Compact is the obvious choice. And if you want the ultimate in Dobsonian evolution, the Obsession Ultra Compact 18" is it.
No compromises. The UC uses the same proven design criteria and materials that made the Classic Obsession so successful and the most copied larger aperture dob on the market. We use the same premium optics from OMI that we do in our Classic series of telescopes. Diffraction limited and all figured and tested with interferometry. Ion deposition 96% enhance primary coating. Two inch flex free glass. One tenth wave 96% Diamond brite secondary mirror. As with our Classic series, you cannot get better optics at any price anywhere. OMI is so confident of its quality that it posts the serial number and test data for every mirror they make on their web sites for everyone to review. Nobody else does this.
18" UC vs 18" Classic |
||
Obsession 18" UC |
Obsession 18" Classic |
|
| Eyepiece height at zenith | 67 inches | 71 inches |
| Set up time including nylon light shroud | Same for both | |
| Ease of use (setup, take down, collimation) | Same for both | |
| Ease of Motions (hand guiding) | Same for both | |
| Construction/materials | Same for both, except: | |
| components covered with satin black laminate | components are stained and have six coat polyurethane finish | |
| Bearing geometry and surfaces | Same for both, Ebony star on etched virgin Teflon | |
| Light baffling | Classic is better with 360 degree upper tube assembly baffle. UC 160 degree baffle opposite focuser. Views and contrast are identical unless there is a nearby street light in the area. If you only observe in the city at home then the Classic is the better choice. If you like to take your scope to a dark site the UC is an excellent choice, especially if you drive a sedan or have limited transport space. | |
| Optics (OMI) (Ostahowski does not offer anything under 18 inches) | Same for both. f/4.2 primary mirror - requires a Paracorr coma corrector for optimum views. Fused silica glass standard on all 18" UC and Classic primary mirrors. |
|
| Secondary mirror | Same 3.1 secondary mirror for both. Central obstruction and image contrast the same for both under good skys. | |
| Coatings | Same for both. 96% on primary, 96% on secondary | |
| Mirror cell | Same for both, 18 point | |
| Wheelbarrow handles | Standard on both | |
| Truss poles | Six 1.25 inch diameter. Connected in pairs at apices. | Eight 1.25 inch diameter. All eight separate. |
| Stability | UC has 6 pole design and Baltic Birch steel reinforced segmented bearings. Much less mass than Classic. | Eight pole design and one piece cast aluminum side bearings. Mirror box and rocker have more mass. Total weight is about 50 pounds heavier than the UC. Classic is a better choice for CCD imaging. |
| Dimensions for transport | 24" x 25" x 12" high. Includes virtual mirror box nested in rocker (will fit in most trunks or hatchback). | 27" x 27" x 26" high (rocker and mirror box) Upper tube assembly placed next to lower unit. |
| Upper Tube Assembly weight (with Feathertouch focuser) | 8 pounds | 11 pounds |
| Weight of heaviest component (includes 2 inch thick standard thickness mirror) | 72 pounds. Includes the virtual mirror box, mirror, and dust cover | 82 pounds Includes mirror box, mirror, and dust cover. |
| Weight at wheelbarrow handles | about 10 pounds | about 15 pounds |
| Weight of complete scope | about 90 pounds | about 140 pounds |
| Clearance width required with wheelbarrow handles attached. (or minimum size of doorway needed to roll in or out with wheels attached) |
29 inches Clearance width needed when carrying UC virtual mirror box is 28 inches. |
30 inches |
18" UC Specifications:
Metric info shown in italics
Primary Mirror:
- 18" - 457 mm Ostahowski, or OMI 2 inch thick mirror
- Fused silica glass standard on all 18" UC primary mirrors.
- 96% reflectivity
- Enhanced Aluminum Coating and Dielectric Overcoat (a supreme coating)
- Center marked for precise collimation
- plus Interferometry certification
see Optics page for more info
Secondary Mirror:
- Pre-installed
- 3.1" - 79 mm United Lens 1/10 wave or better
- Interferogram included
- 96% reflectivity at 550 nm
- Super enhanced Brilliant-Diamond non-fading multi-dielectric coating
see Optics page for more info
Focal Length:
- 72" (± 2") - 1830mm (± 50 mm)
Eyepiece Height at Zenith:
- (approximately) 70" - 178 cm
Mirror Cell:
- 18-point
Truss Pole:
- Length: 55" (± 2") - 140 cm (± 5 cm)
- Diameter: 1.25" - 32 mm
- Wall Thickness: 0.035" - 0.9 mm
Upper Assembly:
- Diameter: 22" - 56 cm
- Height: 13.5" - 34 cm
- Weight: 6 lbs. - 2.7 kg
Lower Assembly:
- Virtual Mirror Box stacked in Rocker for Transport
24" x 25" x 22" high
Standard Features and Accessories:
Feathertouch focuser by Starlight Instruments
Standard on all Ultra Compacts
Low profile, Crayford type, 2 inch focuser, with 1-1/4 inch threaded adaptor for filters. Compression rings. Can be swiveled on it's base to the most convenient position. A joy to use and beautiful to look at.
Telrad
Standard on all Ultra Compacts
External light baffle
Standard on all Ultra Compacts
Counterweight kit
Standard on all Ultra Compacts
Wheelbarrow handles
Comes standard on all Obsessions 12.5" through 25" at no extra charge.
Primary Mirror Coating
Enhanced Aluminum - 96% reflectivity, with dielectric overcoat (a supreme coating) standard on all primary mirrors. See Optics page for more info.
Secondary Mirror Coating
An Obsession exclusive - Super enhanced Brilliant-Diamond is standard on all Obsession secondary mirrors. This premium multi-dielectric coating has 96% reflectivity at 550 nm. The ultimate coating for the deep sky obsessed. This coating is standard on all Obsession secondaries at no extra charge. Brilliant-Diamond is just one of the reasons Obsessions out perform all others.
With 96% enhanced on the primary and our standard 96% Brilliant Diamond secondary, the optical system is equivalent to an extra 2" of aperture!
12 volt cooling fan
12 volt cooling fan comes standard on all Classic and Ultra Compact scopes.
Fused quartz
18” UC Obsessions use fused quartz for the primary mirror glass.
Optional Accessories:
See the Accessories page for more info on these items
Paracorr
$475 (Highly recommended at f/4.2)
Ripstop Nylon light shroud
(Highly recommended)
Barlow-Laser Collimator 2" barrel
(Highly recommended). Includes 2" magnetic barlow lens and mask for the new barlowed laser collimating technique. Great visual aid and no better way to accurately align fast Newtonians. learn how
Argo Navis digital setting circles
with ultra res 32K encoders
ServoCAT Goto Drive System
Dew heater for secondary mirror
Secondary mirror heating system automatically senses the air temperature and the mirror temperature, then maintains the secondary at a preset (adjustable) temperature above the ambient air temperature to prevent dewing or icing.
Pre-installed (if ordered).