Looking for a guide to help you learn the fine points of building everything from large Dobsonians to tiny travel scopes, and to help keep you from making expensive mistakes? Look no farther. Learn to design and build telescopes, from tiny light-weight models to some of the largest Dobsonians on the planet. TMD is filled with the information you are looking for to make your next project a success!

Can you imagine an 8" f/6 that only weighs 25 pounds and folds up into a 12x12x13" box? Here are the photos.

Travel Scopes

Tom Clark pioneered these fold-up designs where all the parts nest inside of each other for easy transportation and storage. The mounts are rock solid, while being easy and fast to assemble.

This 18" f/5 was built for a trip to the southern hemisphere in 1994. Total weight is 97 pounds. We observed with it from Lake Titacaca in Bolivia, at an altitude of 12,800 feet. What views!

Nesting Design for Portability

Large Telescopes


Tom built The Yard Scope in 1992 and it was one of the largest amateur instruments in the world at that time. The 36" f/5 mirror is one yard in aperture - thus the name. The 540 pound monster is one of the most famous amateur telescopes ever built. The 360 pound 36" f4.5 Yard Scope II was built in 1998 and used at the author's home in Chiefland, FL until replaced with a larger instrument in 2003.

Order your copy of The Modern Dobsonian today, and learn from the author's 25 years of experience in building telescopes. Mail your check to: 


Tom Clark

5450 NW 52 Ct.

Chiefland, FL  32626



Only $12.95 + $3.50 shipping to your US address.

Medium Size Telescopes


The most popular amateur scopes are the 12-20" sizes.

    Under the name Tectron Telescopes, Tom Clark has built nearly 200 telescopes for customers around the world. On the left is an early 25" f/5 that weighed 250 pounds. On the right is the 24" f/4.5 that replaced it when we started building ultra-lights. This 24" f4.5 only weighs 160 pounds, yet is ultra-stable. It folds up into a 30x30x24" box for traveling.

Here is the author with a 32" f/4.5. It features a removable mirror box to make set up very easy. This scope could be set up with two guys in less than 10 minutes. Any scope that is easy to transport and set up is one that will be used a lot.

Above is Tom's 24' home-made dome that is on the edge of the club observing field in Chiefland, FL. The scope is a 42" f/4. It is 14' long, weighs 1600 pounds, and has a go-to drive to make observing from inside the dome a pleasure. Watch the observatory and telescope construction in this side show.

Tom lives in the Chiefland Astronomy Village in north Florida. Serious astronomers are welcome to join us for some of the finest observing in the east. We have members from 18 states who regularly come to Chiefland for astronomy vacations. Chiefland.htmlChiefland.htmlshapeimage_5_link_0

Compare the size of the non-folding 6" f/8 with the folded up 8" f/6, 12" f/6, and 24" f/4.5. The 24" takes less floor space than the 6" does. The cart the scope is sitting  on allows the author to easily load  the scope into his van by himself for trips to star parties.

This 10" f/5.6 weighs 56 pounds and isn't a lot bigger than the 8", yet provides excellent views.

TMD shows the construction of my 18x18x20"

12" f/6 that only weighs 54 pounds. (photo below)

Tom Clark and Vic Menard worked together building these foam and fiberglass 16" and 20" fork-mounted Newtonians in 1986. They were featured in Sky and Telescope in 1987.

Tom's workshop in 1992 with six 15" f/5s under construction. Tom retired from Tectron Telescopes in 1999 and no longer builds scopes for customers.

First published in 1992    This is the fourth printing - revised in 2005  

8.5" x 11"  80 pages

The Yard Scope 36" f/5

The Yard Scope II  36" f/4.5

24" f4.5

8" f/6

6" f/8

Tectron Telescopes  Tom's latest telescope making projects and the occasional scope for sale.


Astro Memories     Sharing twenty-five years of being a telescope maker and amateur astronomer.


The Chiefland Observers  If you would you like to visit one of the finest observing sites in the country, here is our group's web page to get you started. This is your invitation to look through a 42". Email ahead please!


Tom's Telescope Making Album. Covers 25 years of telescope making, and shows the evolution of Tom's Dobsonians from the first non-folding scopes right through the design of today's best folding telescopes.


The Dome and the Beast  Watch the construction of Tom's 24' observatory dome and  42" go-to Dobsonian.


Talk to the Astronomy Gods - An article about observing with very large telescopes.


Star Parties of the USA.   A short version of Tom's presentation on visiting the major star parties in the country.


It's the Seeing, Mate    - An article on large scope observing at the Winter Star Party


The Chiefland Experiment  Part I   Learn about how the Chiefland Astronomy Village was started.


The Chiefland Experiment Part II    Read about living at and running an astronomy village.


Collimation     This article on collimation appeared in issue #17 of Amateur Astronomy Magazine and covers using Tectron collimation tools. They were designed by Tom in 1986 and produced until 2007 when Tom retired. For over 20 years they were the best collimation tools available.


Observing Etiquette      If you are new to astronomy, here is an article to get you up to speed on how to fit in  at observing events. This article first appeared in  Sky and Telescope in 9/93, and it ran in Amateur Astronomy Magazine in #18, summer 1998.


Living at a Dark Sky Site     This 2002 article was published in Amateur Astronomy Magazine


Thanks, Astronomy  Tom retired from editing Amateur Astronomy Magazine after #54, Summer 2007. In this farewell article, he describes what the hobby has meant to him and Jeannie.

Above and below are Tom's personal scopes. The 8" and 12" fold up so small that they can be carried anywhere. The 24" is used in our yard at Chiefland, and taken to star parties around the country.

24" f4.5

12" f6

12" f/6

24" f4.5

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