What lifespan does a telescope have?

[Syntarsus]

I'd kind of assumed that with no moving parts telescopes last forever. However then I came across this comment which surprised me from the Orion-Optics site:

We are frequently asked how long do aluminium coatings last for before the mirror (s) need re-coating. This is virtually impossible to answer because it depends on how well you look after your telescope's optics. Keeping them dry and ensuring all moisture (dew or condensation) is allowed to dry off before putting your telescope away should give easily 10 years of service before a re-coat.

So do mirrors need re-coating every now and then and if so is cost effective on the cheaper scopes (for instance something like the much recommended 200p)? How much does it cost?

Are there other parts that need replacing now and then?

Are refractors better than reflectors in terms of low maintenance or as an investment?

Should you expect a telescope to last a lifetime or do they eventually reach a state where it's not worth repairing them?

Thanks

Steve

[swamp thing]

I believe "Galvoptics" offer this service at very reasonable rates.

I had my 10" done a couple of years ago and it was only few tens of pounds rather than the few hundreds to replace it.

Since it has been done I have compared my old recoated 10" against a brand new Skywatcher and the performance is the same.

Regards Steve

[Starbabe]

I would imagine less than 10 years if you live in a high rust area, seaside, mountain etc.

[umadog]

Yes, you have to re-coat Newtonian optics. The coatings may last 2 years or they may last 8 years. Depends how often they get damp and it depends how good the coating job was. Re-coating a mirror is a non-issue and isn't terribly expensive. It's definitely worth re-coating an 8" Newtonian when it's necessary. Other than that, if you're buying a telescope with no electronics then there's no significant maintenance to do. You may need to replace Teflon pads, perhaps. No reason it shouldn't last for decades.

Refractors don't require this re-coating since the lenses, whilst coated, are comparatively tough. The down-side with refractors is that they cost a lot more per inch of aperture and they're harder to mount. An 8" refractor is more or less unheard of, whereas an 8" Newtonian is very common.

[haitch]

Ihad great views through my dob even before I refurbed it (an 80s scope built in Wales) and 1/2 the coatings were completaly missing so even when you notice a little deterioation don't panic.

I've now got Hilux caotings from Orion Optics - not cheap for a 14" but should last a fair while longer than standard coatings.

[Merlin66]

The 200" at Palomar was built in the 1940's - the mirror has been recoated regularly ever since and I hope it has another 70 years of life left in it.

Telescopes will live for ever. Usually outlast their owners!

[brantuk]

Scopes last untill you get aperture fever - then you have to sell it and get a bigger one - but you never get to use it cos you have to do loads of overtime paying for the thing lol

[NGC 1502]

Should you expect a telescope to last a lifetime or do they eventually reach a state where it's not worth repairing them?

Steve

Hi Steve, all good comments already given.

But if the scope is a hi-tech model then I think the story is different. Not many of us expect a washing machine or television to last for decades, so a 'bells & whistles' scope probably wont either, at least not without repairs now and then.

Regards, Ed.

[Charon]

Sad thing but nothing lasts forever.

[jamespels]

As with everything, it all depends on the scope, how complicated it is, how well built it is and so on.

I have a TAL (Russian scope made in the same place as they make mortar tubes - the OTA looks like it comes from the same stock); these are built in the military style (just enough essential parts - yes, that is where "JEEP" comes from, well engineered, easy to service) and I fully expect it to outlive me. That said, it still needs regular servicing (strip down & re-grease every year; replace worn out bearings as necesary - some will last the life of the scope but the harder working ones will wear out in a few years; sooner or later the motor drive will fail and need replacing and so on). Also, as others have said, the mirror will need resurfacing at some point (when will depend on the local conditions and how well you look after it). All of this helps keep an excellent scope performing well and is a modest cost (last rebuild cost me about £40, including getting a local smith to drill out and re-tap two siezed grub screws) and well worth it in my opinion.

Some of the cheaper scopes will not last nearly so well but SW are comfortably at the point where I would expect the 200P to have a long useful life and it will be very cost-effective to keep and maintain it.

HTH,

J.

[Syntarsus]

Not much to add but thanks for all the informative replies.

[haitch]

There is another point , of course... Glass is not a solid but a super cooled fluid. It is flowing so eventually a mirror or lens will lose it's figure. No idea how long that would take and there are a number of factors such as orientation in storage and regularity of use that will affect it.

[Merlin66]

Agreed...but I think it takes much more than a couple of lifetimes....I've seen tests done on With/ Calver glass mirrors which were produced in the mid 1880's and the figure was still perfect!!!