I mean, they’re basically a set of mirrors and lenses in a tube on an equatorial mount, right? And the cost of lenses has come right down. And the mirror could be made in a mould, right? Sure you can add on the fancy motorised mount and goto features, but they’re not necessary.
Is it just that they’re not mass-manufactured?
Alas, this is purely academic as I can’t afford a scope, and even if I could, I live in an area of severe light pollution (if there’s snow on the ground, I can read without the lights on).
There are plenty of reasonably good, cheap telescopes. Celestron make on for $50. Once you stat going up in quality, though, prices tend to skyrocket as the component quality and the build quality goes up, while the demand drops off. You can’t pay Fiat prices and expect a Ferrari F1 car.
But why? Why does a 16" cost north of $10K when a 8" from the same manufacturer costs a tenth of that? Lenses can now be made by machine, and I’m assuming that the mirrors can too. Larger components can’t cost all that much more, can they? After all, they’re just pieces of glass and steel.
I can only assume that not only the material cost goes up with larger scopes, but to manufacture and assemble high-precision instruments takes time and money. Also, as Tapioca Dextrin mentions, demand drops off, which will drive up costs.
Higher quality scopes, have higher quality materials that go into them. From the lenses and mirrors to the coatings, alignment and quality control standards. There’s a ton of variables, but cheap materials, construction and assembly will only get you so far. When you want to go further, I’m sure the cost will rise exponentially with regards to the quality, power, and resolve of the instrument.
Lenses are cheap now? That’s news to me. High quality optical glass is as expensive as it ever has been so far as I know. Certain sorts of lens elements (aspherical, for example) have gotten cheaper, but on the whole the maxim in photography is that lens values depreciate very slowly.
As for why a 16" scope is 10x more than an 8", these sorts of things don’t scale in a linear fashion. The 16" mirror has 4x the mirror area of an 8", keeping 4x the area entirely free from defects is going to require a jump in QA procedures, and the big jump in price will mean a big drop in unit volume so economies of scale are going to be lost.
I hope these posts have explained why quality telescopes are expensive. The tolerances in both the lenses/mirrors and the mechanical parts are very exact if the scope is to perform properly.
As has been noted, there are a raft of cheap scopes, but they mostly will prove so aggravating that most people who buy them give up in frustration.
If you want the most bang for the buck, look at Dobsonians. The are big tubes with large mirrors, an eyepiece holdernd a tripod. You guide them by hand and don’t need an equatorial mount or a wedge.
Also, check with astronomy clubs locally looking for a good used one. Often members have to sell a scope as they no longer can observe, or have moved up to a better instrument. Be very wary of any advertised that you cannot see and try out yourself.
Finally, you may want to check a library for books on telescope making. Many people not only grind their own mirrors, but make all the parts to get a fine scope for a fraction of the cost of buying one.
And many backyard astronomers drive long distances to get out of the light pollution. Local clubs may have star parties at distant places where you can carpool. I’d hate to see you give up an interst in astronomy too quickly.
It’s even worse than that. A 16" telescope is about twice as large in every dimension, so it has eight times as much stuff in it. Also, there are way fewer 16" telescopes made. The tendency of massive objects to deform under the force of their own weight, which makes ants able to carry several times their own weight but makes elephants barely able to carry themselves, is also harder on bigger telescopes, because having the parts shift by a quarter wavelength of light is equally bad for all sizes of scope.
But telescopes are pretty cheap when you compare them to camera lenses of about the same size.
Sure, the mirror blank can and probably is made in a mould. However, it must then be ground to a very precise curve, and polished into an even more precise one. IIRC the minimum tolerance for the surface of the mirror of a Newtonian reflector is that it must be within one quarter of a wavelength of light. This is roughly 0.00000581 inches, a teeny tiny measurement, of the order of 1/172120 of an inch. And closer tolerances are better. Also, most mirrors aren’t ground to a spherical surface, but instead to a parabola, or in the case more exotic designs, to some assymetrical figure. This can be done using machinery, but it isn’t a really fast process.
Thanks, but even if I could afford a scope, I live in an area of very high light pollution generally (SE England). I’ll content myself with looking at the glorious pics from the big telescopes. As I said in my OP, my interest is purely academic.
When I was a kid, we made our own. We got a book called “Amateur Telescope Making”. We ground our own lenses. It was a slow process and took patience. The scope itself was built out of wood by my dad. When we got done, I could see a gap between the rings of Saturn and the planet. It was a 6 inch telescope and worked great.
The effort and labor required for grinding parabolic or spherical mirrors is actually quite costly. That doesn’t even count the costs of materials. Lenses are even more costly.
Has it? Your eyeglass lenses are not the same as the work needed for objective lenses or the eyepieces. Certainly lenses are cheaper that in the past, but not free or negligible.
no, no! NO!
You cannot do that. The mirror will be disaster, image-wise. Mirrors must be ground and then coated.
Molded lenses are very poor, as would be any molded mirrors. They might be useable for light condensing, but not imaging.
No, but you are ignoring a lot of other parts, such as the focusing mechanism, the mounting of the lenses or tubes (which takes some engineering).
They are pretty well mass-manufactured for a hobby item.
People vastly overestimate how bad their light pollution is: the moon and major planets are barely affected by it, and you can still get good views of some deep sky objects.
I’ve known people in downtown of major cities who can still get some decent views of objects. Don’t begrudge what a telescope, or even your eyes can do with a little effort.
And just outside London to boot.