Nemo's Astronomy World

The 50¢ 20" String Telescope

The Mirror Story - As a veteran garage saler and bargain hunter, I've discovered many treasures, but this is the topper.

    In the spring of 2004 I was running errands on a Friday in Portland, and decided to check out some garage sales (the good stuff usually is gone by Saturday).  I followed a sign to a rather "professional looking" garage sale with a large canopy covering the whole driveway.  I made the circuit and didn't see anything that really interested me other than some plastic coin tubes that I thought might work to put some of my eyepieces in.  I picked out 3 and asked the guy how much.  He said 50 cents, and I said OK.  

    He asked me if I was a coin collector, and I said no, "I'm going to use them for my telescope eyepieces."  He then said, "hey, if you know something about telescopes, I've got something else around here you might be interested in."  He then proceeded to move some boxes in the back of his garage and pulled out this large and heavy plywood box (with hinges and a handle).  

He opened it, revealing a large mirror, and proceeded to tell me that it had been made for the government and had certainly cost a lot to make.  My heart started racing as we got a yardstick and measured it - 20 inches.  It was obviously a reflector mirror - even had a white circle at its center.  

    Since he seemed to know that it cost a lot to make, I figured he would know what it was worth (way beyond my budget) - but I hesitated to ask.  Instead, I told him I belonged to an astronomy club and I was sure there would be someone in the market for such a mirror, and If he gave me his number and a price, I'd spread the word for him.  Before he'd finished writing down his name, he suggested that I just buy it from him and make a few bucks myself by re-selling it - and announced that he'd be happy with $150.00.

    I thought about it for a nanosecond, and said OK.  I emptied my wallet and produced $139.00.  I told him I would need to go to a cash machine to get the rest, but he said not to bother, $139 was fine - and we loaded it in my car.

    And that's the TRUE story of how I came by my 20" mirror - all because of a 50 cent purchase at a garage sale!

    A few weeks later I took the mirror to Steve Swayze (another RCA member and highly regarded commercial mirror maker) to see if I had a lemon or a gem.  He determined it was an F5 with a "nice edge, nice curve, smooth surface, good correction throughout and no edge problem."  In other words, nearly perfect.   Steve would sell a mirror like this for about $3,000, and offered to buy it from me on the spot.  Tempting, but I had another plan for the mirror.

The Construction Story:  

First Light: August 20, 2006

Telescope Details


Primary Mirror:  20" (508 mm) X 2" (50.8 mm)

Focal Length = 98.75" (2,489.2 mm)

Secondary Mirror: 3.1"


Total Weight ~ 133#

Mirror = 44#

Mirror Cell / Box = 29#

Rocker Box = 47#

Secondary / Focuser = 8#

Poles / Hardware = 5#

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