The ASSA Amateur Telescope Making Class

Amateur Telescope Making (abbreviated as ATM) is a fascinating hobby with an illustrious heritage going back over 400 years. However, it is a bit of an arcane endeavour, so information on the subject can be difficult to find and many frustrating pitfalls await the uninformed. Consequently, ASSA conducts an ATM “class” (actually an ongoing weekly workshop) in Johannesburg, in order to guide people through the process.

The ASSA amateur telescope making (ATM) class has been in continuous operation since its inception in July 1991. The first session was held in the historic Library building at the Johannesburg Observatory, designed by Sir Herbert Baker. Since this room was used for general meetings and had a wooden floor, it was not ideal, albeit conveniently at the ASSA Johannesburg Centre’s home. We were fortunate to obtain the use of the old CSIR weather station north of Randburg (now Kya Sands), which was informally dubbed SPARC (for Space and Atmospheric Research Centre). When that site was sold, we moved back to the observatory for a while, until Parktown Boy’s High School kindly offered their Design Technology centre as a venue. We are grateful for the use of this conveniently-located facility, which has served us well.

Out of this telescope making class arose ScopeX, the annual astronomy and telescope exhibition which has been held for 18 consecutive years. Hundreds of people have flowed through the ATM class to gain the skills and esoteric knowledge required to build their own instruments, many of which have been showcased at ScopeX, to audiences numbering in the thousands.

Why build a telescope?

Because …

  • You can
  • It is fun
  • You will learn new skills
  • It will give you access to the universe
  • It may be significantly cheaper than buying one
  • You can build something tailored to your specific requirements.

Join our ATM class

If you are thinking about building a telescope, and live in the greater Johannesburg area, then why not join us? We have people coming from as far afield as Reitz and Rustenburg, and enjoy a large contingent from the Pretoria Centre.

If you have built a telescope outside this class, we would love you to bring it around to show off, inspire us, and share your experiences.

Frequently asked questions about the ATM class

Q: Who can attend?

The class is open to all who are intrigued by telescope making. While membership of the Astronomical Society is not mandatory for participation, we would encourage you to join an ASSA Centre. This is not only because the class is run under the auspices of the Society, but because enjoyment of your telescope is enhanced by involving yourself in the complementary activities of the Society.

We try to cater for both the beginner (who has not yet completed a telescope) and the advanced (who have successfully completed at least one telescope).

If you do not wish to join the class, but would like to know what is involved in building a telescope, you are welcome to drop in and observe. We will try to answer any questions you might have, but remember that the class members have priority when it comes to having our attention.

Q: Where is the class?

The class meets in the Design Technology centre of Parktown Boys’ High School. See the map below.

This is situated on the corner of Jan Smuts and Empire roads, Parktown, Johannesburg. Entrance is from Wellington Rd. (parallel to Empire). Go in the gate and follow the driveway to the right – it makes a right-angled bend to the left just as it hits some buildings. The technology centre is the building immediately to the left of the alleyway marked No Parking.

Please don’t park in a no-parking zone: your wheels may be clamped or your car could be towed away. Besides, it would annoy us as we need to maintain good relations with the school, our host.

Q: When does the class take place?

The class runs most Saturday afternoons, starting at about 2:30 PM. You can begin now!

Our classes are pretty much ongoing, though we sometimes have a day out if there are other events on at the school, around major public holidays, and towards the end of the year if the school is being used for Matric exam paper marking.

Q: Who do I talk to join?

When you arrive at the class, just ask anyone and they will steer you to someone who can answer your questions and get you started.

Note that the class is run on an informal basis and discussion is encouraged. This is a “mutual benefit” situation, so you are expected to interact with and help each other as a matter of course.

Q: How much will it cost?

General instruction is provided free of charge by volunteer tutors. Use of the workshop facilities, which you are expected to treat with respect and help keep clean, are provided free by the School.

The class fees can vary from time to time according to the costs of materials, and of course according to the size of the telescope mirror you want. Please ask at the class for the current prices.

All other costs are to your own account, but typically it is possible to build a suitable instrument for about R2000. The money goes out slowly over time, and the actual cost is a function of your expertise, scrounging ability, ingenuity and of course the standard of finish you desire.

To put this in perspective: you should end up with a scope that would be the equivalent in performance of one that would cost you at least 3x as much to buy commercially.

Q: What is included in the class fees?

The fees only cover initial costs of the materials for making the mirror (i.e. glass, abrasives, polishing agents) and a set of notes to guide you through the beginning stages. Glass disks are usually available in a number of sizes, ranging from 4″ to 8″ (100mm to 200mm).

All other costs are to your own account. However, since we help each other, the group also accumulates other materials that can be shared out among the members, either free or at nominal cost. If you have any special skills or materials to contribute to the group, or feel that you may be able to assist in any way in running the class, please volunteer.

Q: What are we building?

Typically a “Dobsonian”, i.e. a Newtonian reflecting telescope on a simple alt-azimuth mounting. If you have any doubts as to which size you want, we recommend going for a 6-inch (150mm). This is the ideal beginner’s scope, manageable in size and easy to build. It will give you access to the craters on the moon, the belts and moons of Jupiter, Saturn’s rings, the polar caps of Mars, and more deep-sky objects than you can comprehensively observe in a lifetime.

After making at least one such telescope, you may wish to try something more advanced. This could be a larger telescope, or a telescope of a more challenging nature. Over time, class members have produced interesting instruments with more exotic optical designs including: ‘fast” (short focal length) Newtonians, Schiefspieglers, Dall-Kirkhams, Cassegrains, folded Herschelians, achromatic refractors, and dedicated solar telescopes. Similarly, novel mountings and tracking platforms, eyepieces, finder telescopes and other associated items are tackled from time to time.

Q: How long will it take?

This is up to you: perseverance and commitment are the key determinants.

Typically you should be able to complete your telescope in about 6 months of spare time, and still have a life. Constant attendance at the class is not mandatory, but is highly recommended if you actually expect to complete your instrument. Building a telescope is a time-consuming and occasionally frustrating business, but the class is your support group. As long as you are prepared to persevere, and listen to instruction, you can do it!

There are those (admittedly experienced) telescope makers who have completed entire telescopes, from first deciding to build it right up to observing with the fully functional instrument, in one week of spare time. Then, there are many who take 25 years (literally), and even more who never complete their first scope. It’s really all up to you. It does take tenacity and commitment, so if you have a habit of giving up easily this might not be the hobby for you.

In the final analysis, no home-built telescope is ever really “finished”. You will always find something you would like to add, change, improve … in the end, you call it “done” and move on to enjoy it. In all probability, if you do get your scope to this point, you will revisit these details later, or build another one incorporating the ideas that come to you over time. If the bug bites, you may find yourself building telescopes forever: you have been warned!

Q: What do I need to bring to the class?

For your first visit, it would be helpful to have a notebook and pen, but that’s it. We will explain all, at the time. Wear casual clothes that you don’t mind getting a little dirty.

Q: Anything else?

All participation in any of the Centre’s activities is at your own risk. You will be expected to sign an indemnity & manifesto at the class. This is because we shall have access to potentially dangerous tools and materials, and to ensure you understand the use of the facilities and how the class runs. (Don’t worry: we haven’t lost anyone yet!) For further details, please come to the class and all will be revealed

Communications

We have a WhatsApp group to which you can subscribe. This is not mandatory, but presents an opportunity to ask questions outside of the class. It is the primary means to notify class members of (for example) events at the school that will prevent the use of the facilities for a period. When you enrol, ask about the WhatsApp group and we can add you. Also, see details of our FB group below.

Resources

Map

Gallery