Thinking About a New Scope? Think Big!
25" f/5 & f/4 Classic
- 25" Specifications
- Mirror Options
- Standard Features and Accessories
- Optional Accessories
- Ordering Information
Dave Kriege with Obsession #2 built in 1989.
Chaco Observatory at Chaco Culture National Historical Park in northwestern New Mexico's San Juan Basin.
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
- Low eyepiece height
- Easier to use for public viewing.
- Rich field of view. Great for star cruising the Milky Way and large deep sky objects. Easier to keep object in field of view.
|10 times the light gathering power of an 8 inch Schmidt-Cassegrain||Obsession
|Limiting stellar magnitude:||17||14.0|
|Rayleigh Resolution Limit:||0.22
(minimum diameter before a
nebular object fades from view)
Jon Isaacs, 25" owner in San Diego California
April 9, 2011
Dave, I am a proud owner of an Obsession Telescope which I purchased used, I am very happy with it and totally amazed at the smooth, stiction free motion, I have owned other Dobs but I was not prepared for the perfection of the motion, standing on the ladder at 520x and effortlessly placing the target just where I wanted it.
I was surprised how easy the 25 is to use. We have a small place on 4 acres in the mountains about 70 miles east of San Diego, the scope lives in the garage so it only takes a few minutes to set it up, I think removing the cover takes the most time.
Tim C., 25" owner in Statesboro, Georgia - March 19, 2013
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.
Metric info shown in italics
- 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
- f/4: 4.0" - 102 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
- f/4: 100" (± 2") - 2,540 mm (± 50 mm)
Eyepiece Height at Zenith:
- f/4: (approximately) 8" - 245 cm
- f/4: Length: 70" (± 2") - 180cm (± 5 cm)
- Diameter: 1.5" - 38 mm
- Wall Thickness: 0.049" - 1.2 mm
- Diameter: 30" - 76 cm
- Height: 16" - 40.5 cm
- Weight: f/4: 16 lbs. - 7.2 kg
- A= 35" - 89 cm | B= 35" - 89 cm | C= 28" - 71 cm | D= 32" - 81 cm
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
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.
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 (standard on all Classics)
JMI EV1 with motofocus
by Starlight Instruments
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!
See the Accessories page for more info on these items
(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.
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
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.
A Deposit is required to place an order ($3,500 for 25" Classic)
Mail the deposit to:
PO Box 804
Lake Mills, WI 53551
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.