Restoring a Children's Classic

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One of the more interesting aspects of being the local "Astronomy Prof", is the little gifts one occasionally receives. When I took my high school and college astronomy classes out to do a star party for the local Elementary school in May, the local paper was there and did a small piece on the event. A few weeks later, the college Dean visited my classroom and dropped off a very decrepit looking (and partially disassembled!) telescope of 1970's vintage (completely covered in dust and bird droppings). The Dean explained that a local senior citizen had come to his office to make a 'donation' to "that nice man who does astronomy for the children." It seems this nice old man was convinced that I needed a telescope just like this one he had purchased for his own children decades ago. The Dean made it emphatically clear that his office was not the Salvation Army Drop Box, but the old fellow was insistent, and - long story short - I got landed with the baby!

A quick inspection showed that none of the glass was actually broken, so I took the messy package home. It seemed like the perfect 'Father & Son' project to keep my 12-year old busy during the summer. The scope was a 50mm f/12 (600mm f/l) on a yoke mount, everything was filthy and most of the metal parts were covered with corrosion. Never the less, we set to work disassembling it - and we were pleasantly surprised!

We began with the 5x25 finder. Unlike so many of the plastic offerings of this sort today, the OTA was steel and the lens cell was an aluminum casting that was actually milled out to hold the objective. The cross hairs (copper wires coated with lamp black) were mounted on a brass cell that was threaded into the eyepiece assembly so they could be brought properly into focus. The 2-element EP was set in a helical focuser that not only kept the cross hairs in focus, but allowed the owner to adjust the finder scope to perfect focus. All the elements were glass, and the "Japan Telescope Institute" inspection sticker on the barrel proclaimed "coated optics". Once the mess was cleaned off, we saw that this was indeed so! The finder mount was intact, and we used oven cleaner (!) to remove the corrosion from the nickel-plated steel screws. A bit of clear tape on the barrel restored the 'perfect fit' on the finder mount and returned it to functionality. The view was surprisingly clear and sharp once it was reassembled!

The OTA was next. We removed the focuser and disassembled it. The nickel-plated steel draw tube was spotted with corrosion, but once again, spray-on oven cleaner and a nylon scrubbing pad worked wonders removing almost all the corrosion spots and restored most of the finish. Unlike bargain scopes today which often use molded plastic focuser parts, ours had an angled rack made of machined brass firmly riveted to the draw tube, and a knife-edge baffle was installed inside to improve contrast! The old grease was very messy and oxidized, mineral spirits and an old tooth brush cleaned that up with ease. We re-lubed with new silicon grease and re-assembled the focuser and threaded on the EP holder - everything now worked as smooth as silk!

The steel OTA was painted flat black inside, we renewed that with a new coat of paint and noted that the OTA also had a proper baffle installed. My son was puzzled by these, and I used a ray diagram to show him how the baffles cut off stray light and how this made the background darker and improved contrast. Nothing like a hands-on lesson in practical optics! The objective cell was also an aluminum casting that had been milled out to accept the objective. This turned out to be a cemented doublet with what appeared to be nice multi-coatings on both surfaces. It took a bit of work to get the objective out of the cell and cleaned up, but once reinstalled, it seemed to be in great shape in spite of all the abuse it had had over the years.

We turned out attention to the tripod last of all, using lemon oil to refinish the wood, and oven cleaner once again to remove the corrosion from the screws. The yolk mount was in pretty good shape, but one of the screws that secured the OTA was missing. We replaced that with a small bolt from the garage. The wooden tripod legs were in good shape, and the thing re-assembled easily. A quick check on the patio to line up the finder (it still worked perfectly!), and we were almost ready for 'first light'.

The star diagonal was indeed a prism (not a cheap mirror), but it had cracked - it was also only 0.965". I had a spare 0.965" - 1.25" hybrid diagonal and a vintage 12.5mm ortho EP which we installed - then we waited impatiently for darkness! As it is about new moon, we chose Saturn for our first target of the night... and rediscovered the frustration of using a yoke mount coupled with a small aperture and narrow fov EP with little eye relief. It was like going back to my childhood all over again!

The yoke mount has a tremendous amount of backlash, especially in the vertical direction, and although the tube moved smoothly and the finder worked perfectly, centering on Saturn took some patience and practice. It was only 50x, but never-the-less, the fov was quite narrow. We could fit Saturn and Porrima all in one field, but not much else! The small eye relief forced both my son and I to remove our specs to use the scope, but Saturn was there in all its glory, and the rings were clearly visible! I searched for Titan, but the moon evaded all our efforts. Even so, there was almost no perceptible chromatic aberration, right out to the edge of the field. The 50mm doublet performed very nicely and the internal baffles made the field very black - contrast was very impressive! When we switched to Antares, the red color was immediately noticeable. Although there was some flaring on Antares, it was not objectionable. We will look forward to trying it out on the Moon next weekend!

Dan

[Ags]

Great write up. The scope sounds good for another 50 years!

[jgs001]

Nice write up, and it looks very nice all cleaned and restored... but yuck.. that objective...

[John]

Thats a good job - these scopes deserve to be looked after and to have young, curious eyes pressed to them

My 1st scope (which I still have) was a 1960's Tasco 2.4" F/13 refractor on a similar mount but with steel legs. On a better mount and with decent eyepieces these scopes can perform extremely well. Minimal CA and really nice star images.

That scope showed me so many objects for the very 1st time - the thrill of discovery was there almost every time I used it

[philj]

Great job Dan, thats another vintage scope saved from neglect. Its amasing what state these scopes end up in after years of abuse but that objective takes the record for dirt I reckon. I have had to clean mold and mildew, paint and other unrecogniseable stuff but Ive never had one that bad so far.

As John says these scopes once you put them on a decent mount can be very good. I have a 1964 Swift 60mm with optics by AXA (Early Takahashi) and this is an excellent scope , Im always amased at just what can be seen with 60mm

Philj

[newman]

I just love stories about restoration, from cars and ships to stuff like scopes. Great job and thanks for sharing the story, I enjoyed the read.

[Ad Astra]

Thanks for all the nice comments, folks!

I figured that for many of you, it would be a trip down memory lane just as it was for me. My first scope was a venerable 60mm Tasco, very similar to this, but with steel legs, that I got for Christmas in 1969. We lived in an apartment over a local store, and I went out into the near 0-degree weather filched a ladder from my Grandmother's house several blocks away, dragged it up the fire escape, then used it to get on the snowy roof of our building... which put me at eye level with a street light. But hey look! Just across the alley the building is 7-feet higher! I bet the ladder could bridge the gap over the alley!

Long story short, with telescope in hand, I "walked the plank" across the alley to get to a darker observing sight. Saturn was absolutely beautiful that night, as was the waxing crescent moon. Until my sister snitched that I was "out on the fire escape" with my telescope. Needless to say, the parents couldn't find me (I had pulled the ladder up after myself and vanished like the Cheshire cat), until my Mom spotted the ladder across the alley. She told me to "come down from there RIGHT NOW!", and then almost had a heart attack when I walked back across the ladder over her head.

Needless to say, I didn't sit down for about a week, and I didn't get to use the telescope for a month.

Never dimmed my enthusiasm for a minute, and last night with my son it all came rushing back. What a thrill!!!

Dan