Thinking About a New Scope? Think Big!



best selling bookbook

179 Pictures, 88 drawings, 34 tables, 475 pages, Hardbound, 6" x 9".

Willmann-Bell Publishing

home-made dobsonian

Don Bailey, 14" f/5 Dob
Smyrna, Tennessee

"The Dobsonian Telescope"

A Practical Manual for Building Large Aperture Telescopes by Dave Kriege and Richard Berry.

"It belongs on the shelf of every amateur telescope maker, and for that matter every Dobsonian owner. With its whimsical style and thorough treatment of the subject the book is destined to become a classic..." Sky and Telescope, October 1998 - read more reviews

Topics covered in this book:

View Table of Contents

Whether you've never observed before, or whether you've been an amateur astronomer all your life, you will benefit from the hands on familiarity and experience in amateur astronomy and telescope making that the authors bring to this book.


Sorry no credit cards. Please pay by check.
$69.95 plus $5 postage to US destinations ($74.95 total)
Foreign orders please inquire for shipping cost.
With your order, be sure to include your shipping address.

Dave Kriege
PO Box 804
Lake Mills, WI 53551

Let me know if you'd like your copy autographed (Dave Kriege only)

Additional Articles Written by or about Obsession

20" telescope components built by Kenneth Pryor using The Dobsonian Telescope book.

Kenneth Pryor

Kenneth Pryor

Kenneth Pryor

Kenneth Pryor

About the book:

This book tells how to build a state-of-the-art Dobsonian telescope using readily available materials and supplies. Every step of construction is detailed in photographs and diagrams, and the underlying ideas are carefully explained. As a result of this three year collaboration between authors David Kriege (Obsession Telescopes) and Richard Berry (Astronomy and Telescope Making Magazines), experienced and well-known telescope makers, you now have the opportunity to build a high-performance telescope from 8 inches to 40 inches aperture based on the thoroughly tested designs described in this book.

The Dobsonian telescope takes its name from the astronomer/philosopher John Dobson, who introduced the concept of inexpensive, large aperture telescopes to astronomy. Amateur astronomers at the time were so amazed that a telescope built from simple, inexpensive materials performed so well that they could hardly believe their eyes. As home-built Dobsonians started showing up at star parties across the nation and people saw what Donsonians could do, the word spread. In just a few years, the Dobsonian revolution swept the world.

Since those early telescopes, Dobsonians have improved dramatically. An entire generation of amateur telescope makers contributed their best insights and refinements to Dobson's original design. Today's Dobsonians are larger, lighter, and more precise than ever before. For example, it is possible to build a telescope of 20 inches aperture that is compact enough to transport in a hatchback automobile, yet takes only ten minutes to set up at a remote dark-sky observing site.

Deep-sky observers especially appreciate Dobsonian telescopes. With the 20 inch (50 centimeter) aperture that the authors recommend for first time Dobsonian builders, hundreds of globular clusters, thousands of nebulae, and tens of thousands of galaxies are visible through the eyepiece. Planetary observers have discovered that from good observing sites, Dobsonians deliver breathtaking performance on the moon and planets. For the casual stargazer, familiar objects like the Hercules Cluster, the Great Nebula in Orion, the Lagoon Nebula and the galaxies of the Virgo Cluster are an entirely new experience.

Lario Yerino and his home built 20" f/5 at Okie-tex star party September 2019.


It was a pleasure to meet you at Okie Tex and show off my telescope.

Your telescope building instructions, as laid out in your book, are clear and very detailed. I enjoyed the process and learned some new construction techniques. By carefully following your instructions I ended up with a nice-looking scope which performs quite well; I have received many positive comments.

One example of the degree of instruction detail is the chapter that directs the size, number, and placement of the Teflon pads needed in order to rotate the scope. In my completed scope, the forces needed to rotate the scope horizontally and vertically are equal, resulting in a scope which can be positioned smoothly.

The year that I built this scope it won first place at the telescope construction contest at the Rocky Mountain Star Stare.

Many thanks,

Lario Yerino

Testimony from Serge Lachapelle

Here is the scope I built according to guidelines and great informations i found in your book "The Dobsonian Telescope", my bible during the construction. This 16" f/4.5 won the first prize award at a local homebuilt telescope competition.

Serge Lachapelle
Quebec, Canada

Testimony from Ken Pryor

A few words concerning "The Dobsonian Telescope" book.  The description of the book really tells it all. "A Practical Manual for Building Large Aperture Telescopes". Believe me when I say without this fantastic book, my scope would not have been possible. Dave and Richard out done them selves with this manual. Every detail is covered, and its step by step process makes building a large Dob a joy. I can testify to all that may contemplate such a challenging project, rest assured if you have the right tools, patience and fortitude you will succeed.

I can't imagine the hours that must have went into such a book. The willingness of Dave to share his knowledge with all ATM's is a testament of his character, dedication, and love for our hobby. My  finished telescope will give me many years of enjoyment under our dark night skies. The mysteries of the cosmos will be sharper and brighter now.

Thanks a million Dave for your book and help throughout the experience, hope to see you at Okie-Tex sometime and shake your hand.

Best Regards,
Ken Pryor

Ken Pryor Ken Pryor Ken Pryor

Ken Pryor Ken Pryor Ken Pryor

Testimony from Glenn Cox

Glenn Cox

Dear David, Thanks for doing for me what your dad did for you all those years ago - teach me how to build a telescope! Given the books dedication you surely understand how wonderful that kind of help can be. The book is simply the best "how to" book ever written. Trust me. I have use these types of books in the following endeavors wine making, auto engine rebuilding, weaving, photography, antique tractors, gardening, raising chinchillas, gold dredging, house design, interior design, landscaping, upholstery, woodworking, shooting, golf, mirror grinding, child rearing and inventing. Nothing comes close to your book. Thorough, understandable, and comprehensive in every sense of the terms. Your book is the best example of generosity of which I am aware. Sharing years and years of hard won knowledge is rare these days. I still have a lot of sanding, staining and finishing to do so I'd better get busy. Sincerely, ~ Glenn Cox

Testimony from Henri MOUHOT


I have a 16-inch telescope homemade.
it was inspired by your obsession telescopes.
This is a great scope very well balanced and very smooth movements.

1 rue de la Liberté
25700 MATHAY

Reviews for "The Dobsonian Telescope":

Sky and Telescope, October 1998

"It belongs on the shelf of every amateur telescope maker, and for that matter every Dobsonian owner. With its whimsical style and thorough treatment of the subject the book is destined to become a classic..." from Santa Fe, New Mexico, 03/03/98

Outstanding guide for constructing a Dobsonian Telescope. If you've ever considered making your own large telescope, this book is the definitive tome. It discusses the practical considerations for building a large amateur telescope with materials mostly available at hardware stores. More important than construction details, the design criteria and simple theory are discussed in detail, so that the builder can intelligently modify the design and innovate new variations on this design. What's remarkable about the book is that it covers construction techniques in detail by one of the leading manufacturers of large Dobsonians and no holds seem to be barred. It's clear that the authors' motive is spreading interest in telescope making and their effort reflects the etymology and highest meaning of the word "amateur". My only quibble is that the authors downplay the rewards of grinding one's own telescope mirror. This topic is covered in an appendix, but further "pride in manufacture" and significant cost savings can be achieved by making your own mirror and it is not such a daunting task. The book is richly illustrated, engagingly written, and an excellent value for $29. from Virginia, United States, 05/04/98

"The Book" if you're thinking about building a telescope. Excellent, interesting, and practical treatment of how you can build a state of the art, large to "giant"(8" to 40"+ aperture!) portable telescope. Uses the right amount of thorough well written engineering theory to justify the surprisingly simple component designs, materials, and construction techniques. The authors clearly want you to succeed. If your contemplating building a telescope based on your preconceptions, forget them, and read this book. The dobsonian approach featured here is a relatively recent major breakthrough in telescope design that few in the general public are aware exists. I can't imagine a "hotter" garage project for a dad to get into with his son or daughter.

Paul Greenhalgh (President)
Fraser Valley Astronomers Society British Columbia Canada

I thought I'd drop you a note to say "THANK YOU" for publishing your wonderful book on how to build an Obsession. As much as we would have loved to purchase one of your beautifully constructed and hand crafted telescopes, as well as support your wonderful company, alas it was to be an impossibility. Our humble club couldn't raise the funds needed to do so. Your unselfish act of publishing this excellent book, made our "wanting" dreams a reality! Our new 20" Obsession style telescope is truly beauty!!! An absolute breeze to use.... the result has been fantastic. I also want to thank you so very much, for your speedy assistance, in getting us the parts we needed, ie: Upper Truss Tube Clamps and Aluminum Side Bearings. The speed in which they arrived was absolutely outstanding! I CAN'T WAIT FOR FIRST LIGHT! Are we Obsessed yet? Dam Straight we are! And it's all thanks to you!!! She's Obsession alright, but built by FVAS members who followed your book to the absolute letter! AWESOME!!!! Clear Skies!

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Other Articles Written by or about Obsession:

For reprints of the publications below please contact the publishers. Do not contact Obsession.

Astronomy Magazine

Telescope Insider

by Bill Andrews

Astronomy Magazine
June 2010 issue

Download PDF

Obsession's New 18-inch scope

by John Shibley
Astronomy Magazine April 2008,
Equipment review for the Obsession Ultra Compact 18 f/4.2 telescope
Kalmbach Publishing 800-446-5489

Obsession Telescopes

A New Obsession Introduction of Obsession 18 f/4.2 UC

Astronomy Technology Today May 2007

Cloudy Nights Telescope Reviews

The 18" f4.2 Obsession UC - Birth of a New Classic

Tom Trusock June 2007

Cloudy Nights Telescope Reviews

Readers Choice - 2007: Top Products

Cloudy Nights Telescope Review

  • Cloudy Night UC 18 review

  • First Look: Obsession 15" UC

Tom Trusock 7/08

Dobsonian Evolution

The Construction of Obsession 1

by Dave Kriege,
Telescope Making Magazine #35 Winter 1988-89
Kalmbach Publishing 800-446-5489

Building the 25 inch Obsession 2

by Dave Kriege,
Telescope Making Magazine #37 Summer 1989
Kalmbach Publishing 800-446-5489

An Observing Ladder for Big Telescopes

by Dave Kriege,
Telescope Making Magazine #41 Summer 1990
Kalmbach Publishing 800-446-5489

R & D and Off-the-Shelf Parts

by Dave Kriege,
Telescope Making Magazine #44 Spring 1991
Kalmbach Publishing 800-446-5489

The Obsession 20, Product Review

by Alan Dyer,
Astronomy Magazine March 1991
Kalmbach Publishing 800-446-5489

Star People

by Robert Reeves,
Amature Astronomy #10,
Tectron Publishing 941-758-9890

The House of Obsession

by Dave Kriege,
Amature Astronomy #14,
Detailed description of how to build a huge roll off roof observatory from an "off-the-shelf" building.
Tectron Publishing 941-758-9890

Build a Backyard Observatory for Peanuts

(House of Obsession or How to Build a Huge Observatory),

by Dave Kriege
Astronomy Magazine June 1997,
Feature article on how to build a huge roll off roof observatory from an "off-the-shelf" building,
Kalmbach Publishing 800-446-5489

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Table of Contents for "The Dobsonian Telescope"

Chapter 1 Large Aperture Dobsonians

1.1 Why Dobsonians Are Newtonians
1.2 How Dobsonians Work
1.3 The History of the Dobsonian Telescope
1.3.1 John Dobson Invents the Dobsonian
1.3.2 The Dobsonian Revolution
1.3.3 Optimizing the Dobsonian
1.3.4 The Second Dobsonian Revolution
1.4 The Dobsonian in Your Future

Chapter 2 Planning Your Telescope

2.1 Non-Telescopic Telescope Considerations
2.2 Tough Telescopic Considerations
2.2.1 Telescope Aperture Considerations
2.2.2 Are You Obsessed?
2.3 How To Get Started

Chapter 3 Engineering the Dobsonian

3.1 Engineering for Performance
3.2 Statics: How to Make a Stiff Telescope
3.2.1 Engineering Terms
3.2.2 The Moment of Inertia
3.2.3 Elastic Deformation
3.2.4 The Strength of Materials
3.2.5 Stiffness of a Truss Pole Flexure in the Rocker Box Flexure of a Telescope Mirror Why Simple Scaling Doesn't Work
3.2.6 Dobsonian Dynamics: How Dobsonians Move Balancing a Dobsonian
3.2.7 Friction in a Dobsonian Friction Defined Dobsonian Friction Curing Stiction
3.3 Materials for Telescopes
3.3.1 Wood Wood Is a Natural, Organic Composite Wood Is Orthotropic Selecting Wood
3.3.2 Aluminum
3.3.3 Teflon
3.3.4 Plastic Laminates "Ebony Star" and "Stardust" Laminates Glassboard Put Car Wax on Laminates
3.4 Protective Coatings

Chapter 4 Optics for Dobsonians

4.1 Basic Newtonian Optics
4.2 Choosing the Mirror
4.2.1 Choice 1: What Aperture?
4.2.2 Choice 2: What Focal Ratio?
4.2.3 Choice 3: Make or Buy?
4.2.4 Choice 4: What Glass?
4.2.5 Choice 5: Cut Sheet or Molded Blanks?
4.2.6 Choice 6: Fine or Precision Annealed?
4.2.7 Choice 7: How Thick?
4.2.8 Choice 8: Blanchard Ground?
4.2.9 Choice 9: What Coatings?
4.2.10 Choice 10: Optical Quality
4.3 Thinking About Eyepieces
4.4 Thinking About the Focuser
4.5 Sizing the Secondary Mirror
4.6 To Offset or Not to Offset?
4.7 Testing Telescope Optics
4.8 What To Do If You Don't Like a Mirror

Chapter 5 The Primary Mirror Cell

5.1 The Flotation System and the Sling
5.1.1 Flotation in Theory
5.1.2 Flotation in Practice
5.2 Building the Flotation System
5.2.1 Flotation System Design Material for Bars and Triangles Flotation System Pads Build the Cell Subassemblies
5.3 The Tailgate
5.3.1 Evolution of the Tailgate
5.3.2 The Open-Frame Tailgate
5.3.3 Tailgate Layouts
5.3.4 Cutting Tailgate Materials
5.3.5 Drill Holes Before Welding
5.3.6 Weld Using a Jig
5.4 Mount the Tailgate in the Mirror Box
5.4.1 Collimation Bolts
5.4.2 Flotation System Hardware
5.4.3 The Sling and Split Bolts
5.4.4 Side Pins

Chapter 6 The Secondary Cage

6.1 Dimensioning the Secondary Cage
6.1.1 The Truss-Tube Advantage
6.1.2 The Inside Diameter of the Secondary Cage
6.2 Constructing the Secondary Cage
6.2.1 Order the Spider and Secondary Holder, and Focuser
6.2.2 Cut the Rings
6.2.3 Make Three Rings for "The Big Ones"
6.2.4 Drill the Strut Seats
6.2.5 Make the Struts
6.2.6 Attach the Struts to the Rings
6.2.7 The Focuser Board
6.2.8 Install the Kydex Light Baffle
6.3 Connecting Ring for "The Big Ones"
6.4 Install the Hardware
6.4.1 Install the Focuser

Chapter 7 Building the Mirror Box

7.1 Holding It All Together
7.1.1 Why the Mirror Box is Stubby
7.2 Mirror Box Materials
7.3 Designing the Mirror Box
7.3.1 Height and Width of the Mirror Box
7.3.2 How Balance Affects the Mirror Box
7.3.3 Calculating the Balance Point
7.3.4 The Depth of the Mirror Box
7.4 Balancing the Telescope
7.5 Split Blocks for the Mirror Box
7.6 The Side Bearings
7.6.1 Making the Mirror Box
7.6.2 Cutting the Sides
7.6.3 The Light Baffle
7.6.4 Assembling the Mirror Box
7.6.5 Side Bearing Dimensions
7.6.6 Bonding Flat Panels of Plywood
7.6.7 Constructing the Side Bearings
7.6.8 Placing the Side Bearings
7.6.9 Mounting the Side Bearings
7.7 To Shortcut or Not To Shortcut?
7.8 The Dust Cover

Chapter 8 The Truss Tube

8.1 How to Build a Serious Truss Tube
8.1.1 Flexure in Truss Poles
8.1.2 The Diameter of the Truss Poles
8.1.3 The Length of the Truss Poles
8.2 Attaching Truss Poles to the Mirror Box
8.2.1 Overview of Pole Sockets
8.2.2 Wooden Split-Block Sockets How to Make Split-Block Sockets Simplified Split Block Sockets Fancy Cam-Action Pole Sockets Strap and Channel Sockets
8.3 How to Align Truss Pole Sockets
8.4 Attaching Truss Poles to the Secondary Cage
8.4.1 The Crushed Tube Method
8.4.2 The Threaded-Insert Method
8.4.3 The Offset-Bracket Method
8.4.4 The Seats and Wedges Method Making Pole Seats Making Pole Wedges

Chapter 9 Bearings

9.1 How Dobsonian Bearings Work
9.1.1 What is Friction?
9.1.2 Friction in the Altitude Bearings
9.1.3 Friction in the Azimuth Bearings

Chapter 10 The Rocker and Ground Board

10.1 Sizing the Rocker
10.2 Rocker Construction
10.2.1 Ground Board
10.2.2 Ground Boards for "The Big Ones"
10.3 Constructing the Ground Board
10.3.1 The Azimuth Pivot
10.3.2 How to Make the Pivot Bolt
10.3.3 Installing the Pivot Bolt
10.3.4 Installing Teflon Bearing Pads Calculating the Size of the Altitude
Bearing Pads Calculating the Size of the Azimuth Bearing Pads
10.4 A Handy Option: Bearing Locks
10.5 Handles for Portability
10.5.1 "It Rolls On Air"
10.5.2 Attaching Handles to the Rocker
10.6 Handling the Big Ones

Chapter 11 Assembly and Troubleshooting

11.1 Last-Minute Preparations
11.2 Installing the Optics
11.2.1 Center-Dot the Primary
11.2.2 Center Dot the Secondary Mirror
11.2.3 Install the Primary Mirror
11.2.4 Install the Secondary Mirror
11.2.5 Adjust the Sling
11.2.6 Collimate the Optics
11.3 Set-Up, Use, and Take-Down
11.3.1 Set Up
11.3.2 Using the Telescope Balance Bearing Surfaces Dew Ventilation Safety Precautions
11.3.3 Take-Down
11.4 Cleaning the Optics
11.5 Troubleshooting
11.5.1 Too Little Focus In-Travel
11.5.2 Sticking Poles and Blocks
11.5.3 Telescopes and Moisture

Chapter 12 Using Big Dobsonians

12.1 Eyepieces
12.2 Filters
12.3 Finders
12.3.1 The Telrad Finder
12.3.2 Finder Telescopes
12.3.3 Get Two Finders
12.3.4 Jumbo Finders
12.3.5 Digital Setting Circles
12.4 Electrical Accessories
12.4.1 Dew Zappers
12.4.2 Heat Ropes
12.4.3 Portable 12-Volt Power
12.4.4 Marine Batteries
12.4.5 Power on the Secondary Cage
12.5 Keeping Warm and Dry
12.5.1 Warm Clothing
12.5.2 Keep Warm with Heat Packs
12.6 Eliminating Stray Light
12.6.1 The Light Shroud Sewing a Shroud Installing the Shroud
12.6.2 Focuser Baffling
12.6.3 The External Light Baffle
12.6.4 The Tailgate Cover
12.7 Telescope Covers
12.7.1 Mirror Box Dust Cover
12.7.2 Hat Box for the Secondary Cage
12.7.3 Secondary Mirror Cover
12.7.4 The Telescope Cover
12.8 Dark Observing Sites
12.8.1 Why You Need a Dark Site
12.8.2 Site Selection
12.8.3 Human Factors

Chapter 13 Epilog: Making a Small Telescope

13.1 Materials You Need
13.2 Overview of Construction
13.3 Begin with the Tube
13.3.1 The Primary Mirror Cell
13.3.2 Locate the Mirror Cell
13.3.3 Finish the Tube
13.3.4 Add End Rings
13.3.5 Assemble the Tube
13.4 The Mounting
13.4.1 Build the Tube Cradle
13.4.2 Side Bearings
13.4.3 Locate the Tube Balance Point
13.4.4 Construct the Rocker
13.4.5 Make the Ground Board

Appendix A Wood as a Structural Material

A.1 The Properties of Plywood
A.1.1 Types of Plywood
A.1.2 The Stiffness of Plywood
A.2 Selecting Plywood for Telescopes
A.2.1 Hardwood Veneer Hardwood Core Plywoods (HVHC)
A.2.2 Hardwood Veneer Softwood Core Plywoods (HVSC)
A.2.3 Softwood Veneer Softwood Core Plywoods (SVSC)
A.2.4 Particle Board

Appendix B Grinding, Polishing, and Figuring Large, Thin Mirrors

B.3 Obtaining a Mirror Blank
B.3.1 Porthole Glass: the Classic Choice
B.3.2 Pyrex Sheet Glass
B.3.3 Choose the Mirror Diameter
B.3.4 Choose the Mirror Thickness
B.3.5 Choose the Focal Ratio
B.4 Grinding Tools
B.4.1 Solid and Built-up Tools
B.4.2 Segmented Tools
B.5 Prepare a Suitable Work Area
B.6 Preparing for Grinding
B.6.1 Facing the Blank
B.6.2 How to Prevent Astigmatism
B.6.3 Bevel the Edge
B.6.4 Grinding Strokes
B.7 Rough Grinding
B.8 Fine Grinding
B.8.1 Fine Abrasives
B.8.2 Getting a Sphere
B.8.3 Going on to #220
B.8.4 The Fine Side of Fine Grinding
B.9 Preparing to Polish
B.9.1 Pitch
B.9.2 Polishing Agents
B.9.3 Pitch Base
B.10 Making the Pitch Lap
B.10.1 Grooving the Lap
B.10.2 Pressing the Lap
B.11 Polishing
B.11.1 Judging the "Feel" of the Lap
B.11.2 Holding the Lap
B.11.3 Completing the Polish
B.12 Testing
B.12.1 Test Stand and Testing Tunnel
B.12.2 Begin Testing Early
B.12.3 Testing for Astigmatism
B.13 Figuring
B.13.1 Goals in Figuring
B.13.2 Rating Telescope Mirrors
B.13.3 Do the Best You Can
B.14 Test Methods
B.14.1 Testing the Sphere
B.14.2 The Sphere and the Paraboloid
B.14.3 Star Testing
B.14.3.1 Doing a Star Test
B.14.3.2 Interpreting the Star Test
B.14.4 Applying a Null Test
B.14.5 Reading a Ronchi Screen
B.15 The Art of Figuring24
B.15.1 High, Low, Long, Short
B.15.2 Figuring Laps
B.15.3 Figuring Strokes
B.15.3.1 The Long, Straight, Central Stroke
B.15.3.2 The W Stroke
B.15.3.3 Tangential Strokes
B.15.3.4 Strokes for Small Polishers
B.15.4 Correcting a Low Edge
B.15.5 Correcting a Turned-Down Edge
B.15.6 Correcting High Zones
B.15.7 Correcting Low Zones
B.16 A Few Final Words

Appendix C Digital Setting Circles

C.1 A Bit of History
C.2 How Digital Circles Work
C.3 Accurate Circles Need an Accurate Telescope
C.4 Installation
C.4.1 Mounting the Azimuth Encoder
C.4.2 Mounting the Altitude Encoder
C.4.3 Mounting the Computer
C.5 General Advice

Appendix D Equatorial Platforms

Appendix E Resources and Suppliers

E.1 Aluminum tubing
E.2 Foam tube insulation
E.3 Double-sided tape
E.4 Specialty tools, knobs and latches
E.5 Threaded inserts
E.6 Levelers (collimation knobs)
E.7 Felt tabs and floor protector pads (mirror cell pads)
E.8 HVHC plywood (Hardwood Veneer Hardwood Core)
E.9 Sliders or cord locks and sling webbing
E.10 Heat ropes
E.11 Heat paks
E.12 Black Ripstop Nylon (for the light shroud)
E.13 Kydex plastic for the light baffle
E.14 E.14 Etched virgin Teflon
E.15 #1782 Stardust Quarry Finish Formica
E.16 #4552-50 Ebony Star countertop laminate
E.17 Glasssboard (bead board or fiberglass reinforced panel)
E.18 Self-tapping threaded wood inserts
E.19 Cam levers
D.20 12-Volt cooling fans
D.21 Ladders (for big telescopes)
D.22 Small parts
D.23 Epoxy resins
D.24 Loading ramps, pneumatic wheels for wheelbarrow handles, and marine trailer jacks
D.25 Black aperture f/ratio labels
D.26 Plastic grommets for light shroud
D.27 Duct tape
D.28 Collimation tools
D.29 Commercial Components for Telescope Making
D.29.1 Optics, focusers, digital setting circles, eyepieces, Telrads
D.29.2 Spiders and secondary mirror holders
D.29.3 Cast aluminum poles seat, clamping wedges, side bearings
D.51 Mirror Making Supplies
A.51.1 Pyrex glass
A.51.2 Kerr dental plaster
A.51.3 MicroGrit abrasives
A.51.4 Optical pitch
A.51.5 Ronchi screens for mirror testing




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