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First Experiences with a Telescope

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#1 Tangerman

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Posted 18 September 2020 - 10:05 AM

Two years ago, a good friend and then roommate of mine and I had a university physics course. As part of that course, we decided to build a telescope for a final project. We found, from Wikipedia, that Newtonian telescopes are relatively simple, so with no other instruction such as books or Youtube videos or this site, we went to work. We got a 3" 800mm focal length mirror from Amazon, the cheapest eyepieces we could find (SVBONY set of 26mm, 9mm, and 4mm), and went to the hardware store and got a bit of wood, screws, epoxy, and 4" wide black PVC pipe. 

The build: We epoxied the mirror to our little piece of wood, then we drilled some holes in the PVC and used both epoxy and screws to attach it to the wood around the mirror. We drilled a hole at about the right height for the eyepieces, and drilled two more holes at that same height. Through those holes we put a wooden chopstick. We found an old mirror at a thrift store, scored and broke it, and attached that mirror to the chopstick using some sort of gummy, non-permanent adhesive. We used the same adhesive to make the chopstick not rotate in its holes. We found, by looking at a faraway sign, where the eyepieces would come into focus. We stacked cardboard on top of the eyepiece hole, with holes cut out in the middle, until that point. Then we took it outside. Oh no! Everything was double! Although I should be amazed this worked at all. The thrift store mirror was like regular mirrors: reflective side protected by glass. The glass surface was giving us an image at a different spot than the reflective surface. We needed a mirror with reflective coatings on the outside.

Luckily, I worked in a chemistry laser lab. My advisor understood what my problem was (laser optics usually have reflective surfaces on the outside). He had a small piece of silicon, nicely polished, I estimate about 50-60% reflectivity, that he was done testing (plus we had more, and larger, samples). So he let me have that, and I replaced the secondary with this. 

My friend and I drove out to a dark site (easy when you're in Utah). We looked at some stars with the telescope, usually leaning the scope against the car as we lacked a mount. It was April, and the setting moon was near Orion. The moon was very cool to see for the first time in a telescope, and scanning around Orion, I found my first fuzzy. I had no charts or astronomical knowledge, I simply got lucky and found M42 on my first try. 

I've observed a lot more since then, and I've upgraded to a 10" Dob. For some reason, I stayed in the hobby, and have been richly rewarded.

Anyone else do everything horrendously wrong their first time and yet still got bitten by the astronomy bug?


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#2 mic1970

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Posted 18 September 2020 - 10:11 AM

Not me, but great story.  



#3 lphilpot

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Posted 18 September 2020 - 10:38 AM

In 1989 I had some half-price quick-focus binoculars (i.e., the "wrong" kind) and stepped out back one night just out of curiosity. That's what hooked me. My first charts were in a book called "Star Maps for Beginner". They were pretty bad, but I kept on. I moved up to a 4.5" f/8 Newtonian on a GEM, a 10" Dob, 14.5" Dob, etc. over time.



#4 ed_turco

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Posted 18 September 2020 - 11:09 AM

My first experience was with a 30 power, 40mm refractor.  I tried it on stars and they were HUGE!  Then I turned it on the full moon,  bumped the eyepiece and learned to focus. After all, I was only eleven years old on the January evening in 1957.

 

The moon was INCREDIBLE!  After that one glance, my life would never be the same.

 

 

Cloudy Nights Article: May, 2015

"The Definitive Newtonian Reflector."
A discussion of the age-old question "Are Apos really better than Newtonian reflectors?" Not!

http://www.cloudynig...reflector-r2983

Sky and Telescope articles:

"Making an Aplanatic Telescope." Nov. 1979: 473-7.
"Tripods from Crutches." Jan. 1996: 31.
"A Scavenger's 12-Inch Telescope". Apr. 1998: 96-97.


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#5 MitchAlsup

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Posted 18 September 2020 - 06:06 PM

 

For some reason, I stayed in the hobby, and have been richly rewarded.

It is a hobby that enriches its participants.



#6 PalomarJack

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Posted 18 September 2020 - 10:40 PM

"Anyone else do everything horrendously wrong their first time and yet still got bitten by the astronomy bug?"

 

No, thanks to Sam Browns All About Telescopes everything I built was/is pretty much on the mark.

 

Besides I don't think you did anything horrendously wrong, you had the right idea, just the wrong secondary. For what it's worth, it probably gave vastly better performance with your original secondary than Newtons first attempt at a reflective telescope. That had a 1" spherical (sort of) primary, a somewhat flat secondary, a simple single lens eyepiece and worked at around f/7, I think. I read an article about it's optical quality after testing it a while back and it was bad, really bad. They did not polish the optics, just tested them with the varnish on them, with a rather bright light source. As far as I know he built one or two more and went onto other things. Just was not into observational astronomy. But as we know, the design is sound and his genius is obvious. Besides the occasional refractor, it's the only design I build.

 

And YouTube for building a telescope? Believe me, you did no miss much. And Wkipedia is good for only telling you about what ATMing is, and not much else concerning it, with way too many words. Couldn't finish it without taking a nap half way through.

 

Cheers...




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