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Made in the USA

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Telescopes


25" f/5 & f/4 Classic


25" f/5 Classic Obsession

Dave Kriege with Obsession #2 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.


25" Classic Obsession

25" (customized)

Custer Institute and Observatory - Southold, NY


M13 comparison

specs




25" f/4$14,995

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.


Advantages of f/4


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

Paul W., 25" owner at OzSky Star Party - April 9, 2014

An exceptional view of the Homonculus Nebula surrounding Eta Carinae. I've noted in the past that this object is the only one that resembles its Hubble Telescope image. It more than resembled its Hubble view this week. It was at least as detailed, if not more, in the eyepiece of the 25" Obsession. I've seen this object on my three previous visits to OzSky, but never before like this.
Paul W.


Tim Conners, 25" owner in Statesboro, Georgea
April 22, 2013

Jon Isaacs 25" Obsession

Dave, Shot these last night with my 25-inch f/5 and iPhone 4S. Used a Baader 90+ percent neutral density filter on my 31 mm Nagler for the Moon photo and just a little post-processing in Aperture.

I'm no astrophotographer, but the Moon shot rivals those in the magazines.

I put a 2.5x Powermate on my 6 mm Ethos for a magnification of 1300x on the Moon. The air would calm every minute or so and I'd get goosebumps from the views. I had to be resolving surface features less than a mile in diameter with that setup.

Tim Conners


Tim C., 25" owner in Statesboro, Georgia - March 19, 2013

Maria Conners

I wanted you to know that my 13 year old daughter, Maria, just took the top award in her school's science fair competition, measuring the orbits of a handful of double stars with my new 25-inch. She had a blast. The judges loved it. And Dad couldn't be happier... Tim C.

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/4 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/4: 4.0" - 102 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:

  • f/4: 100" (± 2") - 2,540 mm (± 50 mm)

Eyepiece Height at Zenith:

  • f/4: (approximately) 8" - 245 cm

Mirror Cell:

  • 18-point

Truss Pole:

  • f/4: Length: 70" (± 2") - 180cm (± 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/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/4.

Interferometry certification included on all mirrors, both primary and secondary. Ion deposition 96% enhanced coatings standard on all mirrors.

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Standard Features 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 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!

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.