Thinking About a New Scope? Think Big!


Big Dob Checklist

Telescope Making 35

It all Started Here...
And It Was Just the Beginning...

Thinking about a large aperture telescope? Obsession is the original premium large aperture Dobsonian. We set the standard and keep raising it year after year. Before you spend your hard earned money, read this checklist. Discover why Obsession is "the telescope of choice" for deep sky enthusiasts.

Ask your self, why do so many Dobsonian manufacturers try their hardest to copy the Obsession? Why did Phil Harrington (author of Star Ware-guide to buying telescopes) say about Obsessions, "the standard by which all other Dobsonian style Newtonians are judged." Why does everyone compare their product with Obsession? Why did Willmann-Bell, the largest publisher of astronomy books, publish our book "THE DOBSONIAN TELESCOPE, A Practical Manual for Building Large Aperture Telescopes"

Ask yourself why... our competition will wish you hadn't.

checkmarkOverall Construction

Outstanding craftsmanship and superior materials is what sets us apart. We use rigid 11 to 13 ply Birch/Maple plywood with furniture grade plys which are beautifully exposed to show off the end grains. Others use 3 to 5 ply, "pretend" birch plywood with covered end grains to hide the truth (Or pay extra to "upgrade"). No one can match the skill of our cabinet makers or the beauty of our 5-layer gloss finish!

checkmarkGeneral Design

All Obsessions are ultra-low profile and balanced for optimum use and enjoyment. Some of the others use counterweights and bulky bottom boxes with several inches of slop between the primary and mirror box. Obsession developed all the innovations listed on this page. We did the R&D that other manufacturers try to copy.

checkmarkPrimary Optics

Obsession uses only the finest diffraction limited optics from Ostahowski, and OMI. All mirrors are 2.0" thick for a stable figure, no flexible ultra-thin 1.6" blanks like some others. Those thin blanks are twice a flexible as our 2" mirorrs. Flexure in ultra-thin mirrors has long been know to cause astigmatism at the eyepiece. Don't compromise here! And because we use only the best optics on the market, our images will make you a believer in large aperture. Coupled with secondary mirrors that have a minimal 15% to 17% obstruction, image constrast on the planets is optimum. When the seeing is good, not only will you get exquisite views of deep sky objects, but you will also see large detailed views of the moon and planets that are better than photographs! It's no secret that at the big star parties the lines are always behind the Obsessions.

checkmarkSecondary Optics

An Obsession exclusive - Super enhanced Brilliant-Diamond is standard on all Obsession secondary mirrors. This premium nonfading multidielectric coating has 98% reflectivity at 550 nm. The ultimate coating for the deep sky obsessed. This coating is standard on all Obsession secondarys at no extra charge. No one else offers this kind of quality - it's like getting an extra inch of aperture for free! With Obsession you get the best reflectivity on the market. Brilliant-Diamond coatings and precision flats from Ostahowski Optics are just two of the reasons Obsessions out perform all others. Our competition likes to compromise here to save money. Ask them where do they get their secondary mirrors. Ask them are they are tested and certified with interferometry. Ask them if they have a dielectric fade resistant 98% coating.

checkmarkMirror Cell

When it comes to cradling the optics, we don't mess around. All Obsessions come with a stainless steel, computer designed mirror cell. We use an 18-point cell on our 18 to 25-inch telescopes.

checkmarkTail Gate

The Obsession mirror cell is mounted in an elegant 3-rung open frame tailgate which permits rapid cooling by the included fan. Design permits primary to be left in the box during transportation and cleaning. If the others use a solid bottom box, removable mirror or less than adequate mirror support, you will regret the difference.

checkmarkSide Bearings

We use our exclusive strong cast aluminum side bearings (properly sized at 1.3 x the aperture) for each telescope we build. Obsession bearings use Glassboard/Ebony Star surfaces which glide on virgin teflon for smooth, "one finger" motion. Others cut corners by using "one size fits all" bearings made of flimsy laminate coated wood.


We use 1-1/4" to 1-1/2" diameter truss poles which mount in laminated cam actionblocks. Others may use skinny hardware store poles and fracture-prone one-piece oak blocks. Our blocks are mounted on the outside of the mirror box for a compact, solid base with easy to reach knobs. Others may use internally mounted blocks which increase the size of the bottom box and are very hard to find in the dark. Our upper cam levers clamps are much easier to engage than other designs. You don't need four hands like the competition's scopes do.

checkmarkUpper Tube Assembly

Obsessions have rings cut from AppleplyTM. With the highest strength-to-weight ratio of all plywood, maple face veneer and gorgeous endgrains, it's simply the best. Standard on Obsessions-an expensive "upgrade" on some others. And our rings are machined round so they look great, not cheap hexagons like some others.

checkmarkFocuser & Board

The JMI-DX3 focuser is standard. Unlike the clunky focusers found on other scopes this premium 2" focuser has super smooth ball bearing rollers that rack in and out easier, holds heavy eyepieces better and is more accurate with laser collimators. Others may cut corners here. It's mounted on a beautiful and rigid curved maple focuser board that matches the radius of the upper tube assembly. Where would you rather place your expensive eyepieces? (Check out our cool brass engraving too.)


Steel wheelbarrow handles are standard on all Obsessions, 15" thru 25". They're warp proof, have 10" pneumatic tires and are stronger and lighter than cheap wood handles. The mirror box, primary mirror, rocker and ground board are transported as a single unit, all quickly and easily rolled about with the wheelbarrow handles. The wheels carry the weight-not you. No need to lift anything. No heavy mirror cell with delicate primary to lug out and hassle with. No mirror box and rocker to carry around. Why struggle lifting heavy components when you can comfortably roll out everything all together on air filled wheels. Set up is fast and easy so you can enjoy astronomy instead of a workout!


No tools, no helper, no fuss, no kidding. 5 minutes, vehicle to deep sky. If other 'scopes require assistance and a bunch of tools, somebody wasn't thinking of your convenience.

checkmarkThose Little "Extras"

Our custom fitted light shroud really fits and sports an embroidered emblem. Custom nylon stuff sack with cord lock closure included. In addition each Obsession also comes with a cast brass name plate engraved with your name. These extras won't improve the optical images but you'll be bursting with pride when you show them to others. Our competition stops way short of these touches.

checkmarkThe Company

Obsession has a solid track record with over a thousand exuberant customers in forty countries (And don't just take our word for it, read the customer comments.