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My first telescope experience by George Brown

Telescope Making > ATM Diaries 3

My first telescope experience
By George Brown - February 2017

Can we help you?
Those were the first words spoken to me at my visit to Scope X.
Yes, I replied, I want to make a 12" telescope.

What do you want it for?
To look at stars, my reply.
Yes we know, but do you want to look at deep space, nebula, planets, or the moon?
I don't know!

What focal length, what f ratio…
What in the world are they talking about!

So for the first two Saturdays, I watched other ATMers grinding, and polishing their mirrors.
They realized that I was truly interested in continuing with making a telescope.
So they proposed making a 6" f6 -f8 mirror.
Little did I know about the work involved with mirror making.

Eventually I settled on making an 8" f6 - f8 mirror.

Now the fun begins.

Two pieces of glass, round, rubbed together over a period of time would produce a work of art; a masterpiece that is finished to within nanometers!
You could have blown my socks off!

So I got down to the "Nitty Gritty "of it - the long grind!
Grit, grit glorious grit, there's nothing quite like it.
"Go", start right off with 80, then 120, then 220, 320, 400, 600, 800, 1000, and finally 1200 and the polishing.

Each grind getting progressively finer and the scratch marks diminishing.
Then slowly, this round piece of glass that was of little significance had a concave surface with a sagitta of approximately 1.96 mm, and an F ratio of 6.45.

To think that only a few months earlier I knew absolutely nothing of the intricacies of telescope making.

Then I get told that you have three things that make you an expert: mirror and tool sticking together, getting a scratch on the mirror, and breaking the tool or mirror.
I can honestly report that two out of the three happened.
I got the tool and mirror stuck together and a "beautiful eye lash scratch."
The scratch came about from working in the garden, dirt under the nails, and forgot to clean my nails.
The scratch is still there as a reminder that you can't be too careful or hygienic (I won't make that mistake next time.)

Now I've constructed the framework and boxes etc, and assembled everything together, and guess what, I've finally got a telescope that I cannot stop talking about!

To think that you can manufacture a "precise piece of workmanship" (without the use of costly machinery) just by the use of your bare hands is remarkable!

Then there's the other telescope makers who give their input and encouragement and without them scope making wouldn't be interesting.
Of course I have to mention Chris Stewart and Johan Smit whose valuable insight and expertise make everything worthwhile.

I've finished my scope, and believe it or not, it's been overcast and raining constantly.
I haven't had the opportunity to view the evening skies.

Next project, a larger telescope possibly 10" or 12", because the bug has bitten!

George Brown

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