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DVD
Free Obsession DVD product Video
To obtain a hard copy of Obsession literature including our 120 minute product video, e-mail your POSTAL address, or fill out this form and we'll mail it to you at no charge (World-wide).

The video is great for determining which aperture is best for you.




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First 18" UC customer, Richard Hammer - Springfield, Missouri




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Gordon Pegue at Okie-Tex 2007




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Bernard Chevalier in France with 18" UC




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Doug Murphy with his 18" UC


See more
18" UC user photos






Telescopes
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Home > Telescopes > 18" UC (Ultra Compact) Obsession

18" - f/4.2 UC

Orders received after June 1st - price will be $6,940.


Large aperture telescope that collapses into a very small package

*The Obsession 18" f/4.2 UC is $6,640 and includes:
  • Feathertouch focuser
  • Telrad
  • External light baffle
  • Counterweight kit
(Same price as Classic 18" with same items).


Watch the 18" UC video. (Quicktime required)
Watch it here or on YouTube



The NEW 18" f/4.2 UC 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. 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.












photos courtesy of
Astronomy Magazine






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 Galaxy and 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 98% Diamond brite secondary mirror. As with our Classic series, you cannot get better optics at any price anywhere. Galaxy and OMI are so confident of their quality that they post the serial number and test data for ever mirror they make on their web sites for everyone to review. Nobody else does this.

Compare the Ultra Compact to the Classic Obsession 18 inch below. You decide which best serves your observing needs. Both scopes provide stunning views, ease of motion, fast set up and a lifetime of observing enjoyment.

18" UC vs 18" Classic
Obsession
18" UC
Obsession
18" Classic
Eyepiece height at zenith 70 inches 78 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 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 or Galaxy) f/4.2 primary mirror requires a Paracorr coma corrector for optimum views. f/4.5 Paracorr optional but not needed.
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, 98% on secondary
Mirror cell Same for both, 18 point
Wheelbarrow handles Standard on both
Truss poles Six 1.25 inch diameter. All six interconnected 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 24" x 13.5" high. Includes virtual mirror box nested in rocker (will fit in any trunk or hatchback). Upper tube assembly placed next to lower unit. 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) 6 pounds 11 pound
Weight of heaviest component (includes 2 inch thick standard thickness mirror) 62 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)
27 inches

Clearance width needed when carrying UC virtual mirror box is 25 inches.
30 inches
Optional custom foam lined ATA travel case (Holds everything except the truss poles) UC uses a case 26 x 26 x 20 high (see below) Classic - No way.


18" UC Specifications: Metric info shown in italics

Primary Mirror:
  • 18" - 457 mm GALAXY, or OMI 2 inch thick mirror
  • 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:

  • 3.1" - 79 mm United Lens 1/10 wave or better. Interferogram included.
  • 98% reflectivity at 550 nm.
  • Super enhanced Brilliant-Diamond non-fading multi-dielectric coating

see Optics page for more info

Focal Length: 75" (± 2") - 1905 mm (± 50 mm)

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 alone folded for Transport
22 x 25 by 12 high
Virtual Mirror Box stacked in Rocker for Transport
25 x 25 x 13.5 high

Eyepiece Height at Zenith: (approximately) 70" - 178 cm

COMPARISON
5 times the light gathering power
of an 8 inch Schmidt-Cassegrain
Obsession
18" UC
Typical
8"
Limiting stellar magnitude: 16.0 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


View Specifications Table for all Obsession Telescopes
English version | Metric version
Download PDF


Mirror Options:
see the Optics page for more info

Obsessions are built with premium diffraction limited optics from Galaxy and OMI (Optical Mechanics Inc.).

Choose from Galaxy or OMI mirrors when ordering.

M13 Comparison

Standard Options and Accessories
  • Feathertouch focuser by Starlight Instruments - standard on Ultra Compact.

  • Telrad - standard on Ultra Compact.

  • External light baffle

  • Counterweight kit - standard on Ultra Compact.

  • Wheelbarrow handles
    Comes standard on all Obsessions 15" through 30" at no extra charge.
    They're not necessary on the 12.5".

  • Primary Mirror Coating
    Enhanced Aluminum - 96% reflectivity, with dielectric overcoat (a supreme coating) standard on all primary mirrors.

  • Secondary Mirror Coating
    An Obsession exclusive - Super enhanced Brilliant-Diamond is standard on all Obsession secondary mirrors. This premium multi-dielectric coating has 98% 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 98% Brilliant Diamond secondary, the optical system is equivalent to an extra 2" of aperture!


Optional Accessories:
See the Accessories page for more info on these items

  • Travel Case - white 26" x 26" x 20" thermo-formed, high-density polyethylene shipping container (foam lined) - $495. (Having scope shipped in this case saves you about $100 in packing costs).
    Case meets the Air Transport Association's (ATA) Specification 300, Category 1 requirements.

  • Paracorr - $295. (Highly recommended at f/4.2)

  • Ripstop Nylon light shroud - $159. (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 super res 10K encoders - $835
    more info

  • ServoCAT Goto Drive System more info

  • 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.
    more info


Ordering Information:
A Deposit is required to place an order ($2,000 for 18" UC).

Mail the deposit to:
Obsession Telescopes
PO Box 804
Lake Mills, WI 53551
USA


You can e-mail your order, or mail it with the deposit.

  • With your order, please list any options and/or accessories you want, your mailing address, e-mail address if any, and phone number(s).
  • After we receive it, we will send you an order confirmation letter.
  • Delivery is usually 1 to 2 months from time of order.
  • Please e-mail for current delivery times.
  • Balance due prior to shipment.
  • Prices do not include shipping and crating. We ship throughout the world via UPS.
  • Any questions, please call or e-mail.
  • NOTE 10% order cancelation charge.

Need more information?
To obtain a hard copy of Obsession literature including our 120 minute product video, e-mail your POSTAL address, or fill out this form and we'll mail it to you at no charge (World-wide).

The video is great for determining which aperture is best for you.


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