We hear this story quite often:
“I was going through my old room at my parents house and I found my old telescope! I hadn’t seen it since I was twelve! I wonder if it still works?”
“My father passed away, and I found this old telescope in his belongings, I never knew he had one. Can it work?”
” I was at a flea market and I picked up this telescope for just $20. Its missing a few parts, I think, but I wonder if I can get it working?”
” We bought a house and while cleaning it out we found this telescope. I wonder how good it is and if it will work?”
“I bought a lapse storage unit in an auction and one of the things inside was this telescope. How much is it worth if I clean it up?”
It isn’t a daily event here at the store, but it sure does happen a lot. People find/refind/salvage an old telescope and they want to know if it is a)valuable or b)can be made to work again.
The short answers to those questions are a) Probably not and b) maybe, but is it worthwhile?
Here’s the facts: almost 90% of the telesco0pe we see brought in to the store are small refractors. They are usually older versions of something like this Orion Observer 60.
Small refractors make up a huge portion of telescope sales today, especially for beginners, and it was no different 10,20, 30, or 40 years ago. They are usually the least expensive models available and were sold in camera shops during the holidays – larger telescope you usually had to send away as mail-order. These small refractors had company names that often are not around anymore: Jason, Telestar, Bauch & Lomb, and so on. Now you may notice from the link above that the Observer 60 has a price of just under $100. Remember that number because as your telescope get repaired it is going to cost money – and at a certain point you might think that maybe getting a new telescope is more economical than repairing an old one.
Still, let’s break this down into different categories of problems:
Unsalvageable – At one astronomy club’s star party I once saw a visitor who had brought his old telescope for the club members. When he tilted the end to the ground the lens fell out – followed by a pint of rust flakes. This was a pretty cut and dry case, but in some cases it might not be so obvious what is unsalvageable.
1) Bakelite telescope bodies – I’d be amazed any telescope with this kind of body survived as long as it did.
2) Plastic telescope bodies – These can vary a lot. Some are actually decent or even ABS plastic. But the models with cheap colorful plastic aimed for very little kids are usually not worth saving.
3) Damaged Tripod legs – The shift in low-cost telescopes from wood legs to aluminum legs only took place about 12 years ago, so most old telescope often have wood tripod legs. Wood is fin but it can warp from moisture or splinter from pressure. If there is damage to the legs or the bracket on the tripod legs odds are it is not worth repairing.
4) Missing main lenses or mirror, missing eyepieces are one thing (see below), but if you telescope is missing the main lens/mirror it will not be worth saving.
5) Bends in the tube. Dents are one thing, a telescope with bent tube simply is not going to work.
6) Rust – usually only happens with reflectors, but rust inside the tube is big trouble. Outside is no so big a deal.
Needs Parts – Most old telescopes are physically just fine but are just missing a few things. Telescopes often have lost the little things that came with it, such as the eyepieces. This is a problem as the eyepieces are need for the telescope to work. The good news is that you can often buy these parts – but it might get harder to do so in the future.
1) Eyepieces – second only to missing diagonals, eyepieces are usually what most found telescopes are lacking. This is not too much of an issue as you can usually buy new eyepieces. Trouble is, when they run $20-30 per eyepiece you use up a lot of that ‘$100’ figure we mentioned earlier.
Another issue with eyepieces is the size. Times were most low-cost telescopes were made in Japan and used eyepieces that had a .965″ (25mm) barrel diameter. The US standard was 1.25″. As time went on and manufacture of low-cost telescopes was moved to Taiwan and then Chine the US standard was used more frequently. This is good as people buying a new telescope have a better design, but it also means that there is less reason to make the smaller lenses. 10 years ago the major telescope suppliers made decent design .965″ eyepieces. But the need for them dried up with the old Japanese models so they stopped making them. If you cannot find .965″ eyepieces you may need to use and adapter and US standard eyepieces.
2) Diagonals are probably lost more often than the eyepeices. They have the same sizing issues and unfortunately can be harder to find than eyepieces in the .965″ standard. Some telescopes can still come to focus without their diagonal, but some cannot.
3) Finder Scope – While lacking a finder scope does not make the telescope useless, it does make it much, much, much harder to use. Usually most old telescopes had a cheap, plastic 5x finder that are difficult to adjust. A LED reflex finder is a much better option, although you may have to buy it and a bracket to attach it.
4) Dust caps – Without dust covers your optics will likely accumulate dust and grime. If these are missing you might want to improvise something as they will be hard to replace. A clean cloth held on by a rubber band can work for short term storage of a telescope.
Mechanics – Things fall apart, but they can often be repaired.
1) Small dents and dings – these usually won’t affect much. Even the most severe dent a tube can take before bending is not likely to block the light path.
2) Tripod parts go missing. Some of these can be lethal to the telescope’s recovery. Brackets that are attached to wood tripod legs can bend or break and are not worth repairing or replacing. On the other hand, often what gets lost are thumbscrew and bolt systems that attach the tripod leg to the accessory tray that keeps the legs properly sturdy. These can usually be replaced at a local hardware store for a small amount.
3) Stick legs. Wood swells. Sometimes it bends but often what happens is that the center portion of the tripod leg swells up and can’t be adjusted. You may need to use some strength to get it loose again and it may require some sanding or grease. No cost to fix this, however. If the swelling results in bent or broken legs, however, you are back into the unsalvageable category.
Optics Cleaning – Unless your telescope was sealed in a box it is likely to have some dust on its optics, or worse.
1) Dust. This can be blown off with a rubber ‘blower bulb’. It is important to clear the lens or mirror of dust if it needs more cleaning in any case.
2) Grime, etc. Lenses can be cleaned with the proper lens cleaning fluid. Look for optics cleaning fluid that is suitable for optical coatings. Don’t use window cleaner. Be sure to use optics cleaning tissues as well as using household tissues and paper towels can damage the lens and coatings.
3) Mirrors with grime. These need to be cleaned, and here are some instructions on how to do so.
This list is by no means comprehensive – the number of things that can be wrong with an old telescope is enormous. But it does give you a sense of what the costs and efforts would be for salvaging an old telescope.