Stellafane Amateur Telescope Making Main Page
Russell Porter
Grinding a Mirror |
"For
it is true that astronomy, from a popular standpoint, is handicapped by the inability of the average
workman to own an expensive astronomical telescope. It is also true that if an amateur starts out to
build a telescope just for fun he will find, before his labors are over, that he has become seriously
interested in the wonderful mechanism of our universe. And finally there is understandably the stimulus
of being able to unlock the mysteries of the heavens by a tool fashioned by one's own hand."
Russell W. Porter
Founder of Stellafane, March 1923
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Introduction
It has been over 10 years since I first published the ATM Page in November 1998. Now in January 2009 I have
started to freshen them up, clarify confusing sections, convert them to our newer web page style, and complete
sections that have not previously been done. This will take months to accomplish, and there may be some
rough edges while the work is in progress. Please let me know
if you find errors or bugs, I'll try to correct them quickly. The ATM pages are the most popular pages on
our web site, and I hope to keep them a very useful resource for the world-wide ATM community.
Ken Slater, Webmaster. A lot has changed since Russell Porter wrote those words - today the "average workman" can afford
to buy an already made telescope and Dobsonian mountings are very popular. Much is also unchanged - mirror
grinding techniques are very similar to those written up by Porter and Ingalls in the 20´s and 30´s. Many amateur
astronomers still choose to fabricate their own instruments, for the pride of accomplishment, the gaining of
knowledge and the insurance of quality. Telescope making is at the heart of the Springfield Telescope Makers
- after all it is two thirds of our club's name - and on these pages we hope to show your that you too can make
your own telescope - and it can be an excellent performer!
A note on ATM techniques: There are almost as many ways to make mirrors and telescopes as there are
telescope makers. On these pages we present one or more ways that have worked for us, but that doesn't mean
there aren't many other valid approaches. In fact, many of us enjoy ATMing because we can experiment with different
techniques and sometimes find better ways of making or building a telescope. And even if our new technique isn't
better, we usually learn something valuable in the process. On these pages, however, we have tried to stick
with simple and proven techniques that are most appropriate for novice mirror and telescope makers, and are
generally what we teach beginners at the Stellafane Mirror Class.
Amateur Telescope Making Table of Contents
General Information
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Provides basic information about telescope for beginners, and briefly discusses important factors that
should be considered in Selecting a First Telescope.
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There are a lot of misconceptions about making a mirror - read this even if you don't plan to make a
mirror, but just want to know how it is done - with your bare hands and a few simple tools,
you can grind and figure a fine mirror with a surface accurate to a few millionths of an inch!
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This page has formulas for many telescope and mirror parameters. It will calculate parameters for two
different telescope designs and compare the results for you. It provides data to help in selecting a telescope,
and also provides information necessary for mirror making and testing.
Telescope Mirror Making
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Pyrex Mirror Blanks
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Grinding
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Polishing in the McGregor Observatory
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Polishing
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Figuring & Testing
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Aluminizing or Silvering
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Mirror Making References & Calculators
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(includes many short videos)
Optical Testing
Cody Tests his Mirror
Testing Overview
Basic Testing Knowledge
Mirror Quality
How good is Good Enough?
- Polish Quality
- Surface Quality
- Figure Quality
Practical Testing
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The Ronchi Test
- Testing for a Sphere
- Testing for Edge Problems
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The Foucault or Knife Edge Test
- Testing for a Sphere
- Testing for a Parabola
The Star Test
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The Stellafane Tester
Complete plans for all the test equipment you need to accurately test and figure your mirror.
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Build a Foucault / Ronchi / Knife-Edge Tester
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to make a Mask or Pin Stick for your mirror.
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on your Inkjet or Laser Printer
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Building a Telescope
We currently do not have any material in this section.
ATM Resources & References
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Information about the publications we use to develop or check the information on these pages.
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Internet Resources on our Links Page
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Hundreds of links to all aspects of telescope making on the internet.
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US suppliers of Mirror Blanks, Grinding & Polishing Supplies, and Telescope Making Supplies.
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Many can offer help with your project.
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A good place to look at various telescopes and chat with their owners.
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A world-wide list of Mirror Making Courses we know about, part of our Mirror
Class section.
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