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Made in the USA

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Telescopes


25" f/5 & f/4 Classic

25" f/5 Classic Obsession

25" f/5

Dave Kriege with his 25" built in 1989


25" f/4 Classic Obsession

25" f/4

Chaco Observatory at Chaco Culture National Historical Park in northwestern New Mexico's San Juan Basin.


M13 comparison

specs

25" f/5$12,495

Orders received after April 1st price will be $12,995.


25" f/3.5$17,995

Plus Shipping & Crating


Forget averted vision. Globulars, nebulae, and galaxies will come screaming out of the eyepiece.

You won't believe your eyes. This is the cure for aperture fever!

Join the realm of Herschel whose famous NGC catalog of deep sky object descriptions are exactly what you will experience.

This is the telescope that Dave Kriege, founder of Obsession, uses for his personal observing.

The Obsession 25 is considered to be the ultimate telescope for the serious deep sky astronomer who can afford the best.

One person set up, one handed guiding, one incredible observing machine.

Try direct vision - you'll get used to it.


25" f/5 vs 25" f/3.5:

The 25" Obsession can be ordered as an f/5 or as an f/3.5.

f/5 (125" 3,175 mm focal length)
f/3.5 (87" 2,200 mm focal length)

Eyepiece height at zenith for 25" f/5 is 10 feet.
Eyepiece height at zenith for 25" f/3.5 is 7 feet.

Advantages of f/5

Advantages of f/3.5

In short, both scopes provide dramatic and exciting views. The f/5 is the ultimate personal scope. It yields better coma free images, but requires two more ladder steps. The f/3.5 is easier for public viewing, but requires a coma corrector like the Paracor.


10 times the light gathering power of an 8 inch Schmidt-Cassegrain Obsession
25"
Typical
8"
Limiting stellar magnitude: 17 14.0
Rayleigh Resolution Limit: 0.22
arc seconds
0.68
arc seconds
Contrast limit:
(minimum diameter before a
nebular object fades from view)
3.4
arc minutes
11.0
arc minutes

Customer Comments

Will O., 25" owner - January 14, 2010

I've only had one opportunity to get out to my dark site since I got the 25" but what a night! My most memorable views were of the Perseus galaxy cluster with NGC1275. I spent 30 minutes in this area and I kept seeing more and more the longer I looked. Thor's Helmet (NGC2359) was beautiful and seemed three dimensional. The detail is so astounding that it takes a while to have it all sink in!

I am most surprised at how easy it is to use a scope of this size. In spite of it's size, I setup and was ready for observing in less than half the time it took with my 16". Any doubts I had about using a large scope were removed after handling this for the first time. Great design and engineering! Will

Read more 25" customer comments


M13

M13
by Dan Price

NGC 891

NGC 891
by Bob Brunck

M27

M27
by Bob Brunck

Saturn

Saturn
by Antonio Roman


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25" Specifications:

Metric info shown in italics


Primary Mirror:

  • 25" - 635 mm f/5 GALAXY, or OMI 2 inch thick mirror
    25" - 635 mm f/3.5 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:

  • f/5: 3.5" - 89 mm United Lens 1/10 wave or better
    f/3.5: 4.5" - 114 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:

  • f/5: 125" (± 2") - 3,175 mm (± 50 mm)
    f/3.5: 87" (± 2") - 2,200 mm (± 50 mm)

Eyepiece Height at Zenith:

  • f/5: (approximately) 10' - 305 cm
    f/3.5: (approximately) 7" - 213 cm

Mirror Cell:

  • 18-point

Truss Pole:

  • f/5: Length: 87" (± 2") - 220 cm (± 5 cm)
    f/3.5: Length: 60" (± 2") - 152cm (± 5 cm)
  • Diameter: 1.5" - 38 mm
  • Wall Thickness: 0.049" - 1.2 mm

Upper Assembly:

  • Diameter: 30" - 76 cm
  • Height: 16" - 40.5 cm
  • Weight: f/5: 15 lbs. - 6.8 kg
    Weight: f/4: 16 lbs. - 7.2 kg

Lower Assembly:

  • A= 35" - 89 cm | B= 35" - 89 cm | C= 28" - 71 cm | D= 32" - 81 cm

see diagram


Mirror Box weight:

  • The heaviest component (what you don't lift): 150 lbs - 68 kg
  • Weight at Handles: (what you lift at Wheelbarrow handles): 40 lbs - 18 kg

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Mirror Options:

Obsessions are built with premium diffraction limited optics from Galaxy and OMI (Optical Mechanics Inc.). See Optics page for more info.

Choose from Galaxy or OMI mirrors when ordering 25" f/5.
Only OMI supplies mirrors for our 25" f/3.5.

Obsessions are also available without optics if you already have your mirrors. Call, fax, or email for price and delivery.

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Standard Options and Accessories:


Choose from four great focusers

The JMI EV3 comes standard on all Classic Obsessions. Or upgrade to the EV1, or EV1 with motofocus, or the awesome Feathertouch by Starlight Instruments. See the Focuser Options page for more information.

JMI EV3

JMI EV3 (standard on all Classics)


JMI EV1 with motofocus

JMI EV1 with motofocus

JMI EV1

JMI EV1


Feathertouch by Starlight Instruments

Feathertouch
by Starlight Instruments


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 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


Counterweight kit

(you supply the lead shot or sand) Recommended if you intend to use heavy barlow/eyepiece combinations, a Paracorr coma corrector, a traditional finderscope, or the Argo Navis digital setting circles.


Telrad


Ripstop Nylon light shroud


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

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

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Ordering Information:

A Deposit is required to place an order ($3,500 for 25" Classic)

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.