advice on telescopes
July 16, 2004 1:10 PM   Subscribe

I am interested in buying a telescope for someone who moved into a condo that has a great view of the Chicago skyline as well as an ocassional awesome view of the moon. The telescope would be used mainly for looking at other buildings as well as for viewing the surface of the moon when it is full and close. The thing is, I know absolutely nothing about telescopes. I've done some research via google and am at a loss. I also called a hobby shop but the sales person was extremely unhelpful. Could someone knowledgable about telescopes give me some advice about brand, kind, size etc.?

also, I am looking to spend between $200 and $300.
posted by alicila to Technology (17 answers total)
for astronomy, the aperture of the telescope is what is most important (the size of the hole at the front). this means that you probably want a reflecting telescope (one with a mirror to collect the light) rather than a refracting telescope (one that uses a lens), because big mirrors are cheaper than big lenses (all professional telescopes use mirrors).

reflecting (mirror) telescopes are short and fat (they look a bit odd), refracting telescopes (lens) are long and thin (what you traditionally think of as a telescope).
posted by andrew cooke at 1:17 PM on July 16, 2004

(so get a short fat one)
posted by andrew cooke at 1:18 PM on July 16, 2004

(the reason aperture is important is that you are trying to see things that are faint - not so true of moons and buildings, but true if you want to look at planets or galaxies. if you're only looking at moon and buildings then that may not matter so much.)

also, the moon is always more-or-less the same distance away. it sometimes looks really big on the horizon, but that's an illusion. really.
posted by andrew cooke at 1:20 PM on July 16, 2004

Binoculars might be an interesting alternative to a telescope. More portable and easier to aim.
posted by Nelson at 1:37 PM on July 16, 2004

If you are using it for shorter focus applications (buildings and such) you will probably not want a "real" telescope, celestron has a range of spotting scopes that work for both applications. I haven't tried these, but the celestron stuff in general is decent. Dealtime has a category that might help finding the prices.
posted by milovoo at 1:54 PM on July 16, 2004

Also, (big advantage) the spotting scopes do not flip the image, it's not as much fun to view a skyline upside-down.
posted by milovoo at 2:09 PM on July 16, 2004

If it were for you, I'd recommend getting a pair of good 7x35 or 10x50 binoculars; if you actually use them, then get a telescope. But it's not for you.

For skylines and the moon, you don't need a big aperture. I'd second milovoo about getting a spotting scope.

DO NOT UNDER ANY CIRCUSTANCES WHATSOEVER get a telescope from a department store (or similar) or a full-service hobby shop. 99 times in 100 it will be pure dogshit.

UTTERLY IGNORE the magnification of the telescope. That is not what makes it good. What makes a good telescope are quality optics and construction and, for astronomy, a big fat aperture. You can get more magnification anytime you want by buying a Barlow lens.

Some respectable telescope brands are Celestron, Meade, TeleVue, and Orion. BUT at least some of these also seem to sell dogshit telescopes through department stores, so be a little careful.

$200--300 will get you something quite nice.
posted by ROU_Xenophobe at 2:23 PM on July 16, 2004

Argh. Posted before I was done.

Go pick up the latest issue of Astronomy or Sky and Telescope, and you'll have a good sense of what's out there.
posted by ROU_Xenophobe at 2:24 PM on July 16, 2004

yeah, sorry for focussing (ha) on astronomy. i agree with everyone else really.
posted by andrew cooke at 2:51 PM on July 16, 2004

There are two types of telescopes: reflecting and refracting. Reflecting telescopes have a giant mirror that collects the light, and a secondary mirror somewhere in the path that redirects the light to an eyepiece, where the actual "magnification" takes place. Refractors use giant lenses to magnify the light -- these are your standard "guy on a ship looking for land" telescopes.

There is one subset of reflectors called Shmidt-Cassegrains. With these telescopes, there is a mirror at the back, which takes the light and aims it at a mirror at the front, which takes the light and aims it back to an angled mirror where you look in. The reason for the extra mirror is that with a normal reflector, the point of focus is usually waaaay down at the other end of the scope. A big mirror = a very long telescope. With a SC, you can effectively halve the length.

What you want will depend on how it will be used. If you just want to peek in the neighbors apartments, I'd go along with everyone else and recommend a good pair of binoculars. For $300 you can get some nice ones. If you want to use it for star-gazing, or astrophotography, you're do well to get one with an equatorial mount, which moves the telescope slowly in conjunction with the movement of the Earth (so the object in the eyepiece stays still). These don't come cheap, however, and weigh a ton.

If you want a basic scope for simple astronomy, I'd recommend a 4.5" - 6" reflector. Meade is the creme-de-la-creme of Schmidt Cassegrain designs; they have computer controls on their mounts where you plug in your location on the Earth and the time of day, then tell it to show you, say, the Andromeda Galaxy, and it automatically moves the scope in the correct position. These will run you a couple hundred more than you're willing to spend, however.

You can get a smaller Meade refractor, with "AutoStar" technology, for about $300 -- the ETX 70AT Telescope, for example.
posted by Civil_Disobedient at 7:08 PM on July 16, 2004

This guy has an 8" on a equatorial mount (no drive motor) for $385.

Here's a 6" Newtonian Reflector (standard reflector) for $120.

Look around, there are deals to be had.
posted by Civil_Disobedient at 7:26 PM on July 16, 2004

I would advice you to get one with an equatorial mount (as opposed to an azimuth-elevation one). Even with a modest telescope you can see Jupiter and Saturn and with a properly aligned equatorial mount you can follow them by turning only one knob at a time making it less frustrating for beginners. The skyline doesn't move so the mount isn't that big an issue for that although it will be less intuitive to use than an Az-El mount for that application. Also some beginner models include what I believe is called an erecting lens or eyepiece that you can use so that the skyline doesn't appear upside down.
posted by golo at 1:24 AM on July 17, 2004

You can also ignore my advice and go straight for a motorized telescope that nowadays can be surprisingly inexpensive. Even with moderate light pollution astronomy can be an entertaining hobby, especially for those of us that don't go out so often. I also recommend to get a beginners book. 99% of the dots we see in the sky will still look like dots through a telescope and a book can help you to find those objects that, depending on the person, might slightly amuse them or blow their minds.
posted by golo at 1:41 AM on July 17, 2004

one cautionary point - astronomy through a telescope is nothing like the pictures you're used to seeing every day in newspapers and on the net (which are typically from the space telescope or space probes, and so way above the atmosphere, or from huge telescopes that can look at much fainter detail than a $300 or $3000 amateur instrument). mars is a slightly red blob. venus is a slightly striped blob. saturn's rings are little more than an oval blob. galaxies are fuzzy blobs. unless you're really keen on astronomy, the moon is the only thing worth looking at, and binoculars are fine for that (disclaimer - bitter ex-astronomer speaking ;o).

just in case you're thinking "oooh, maybe astronomy is interesting"...
posted by andrew cooke at 5:33 AM on July 17, 2004

I just wanted to second the mention of needing an equatorial mount telescope for astronomical viewing. When I was a kid my grandparents bought be a refractor telescope without such a mount and I found it very frustrating trying to look at the moon through it. The moon moves surprisingly fast through the field of view of a 'scope - you end up spending much more time adjusting and moving the 'scope to keep up with it than you do actually looking at it. My dad had an equatorial mount scope that allevieated this problem.
posted by dnash at 9:56 AM on July 17, 2004

thanks everyone. what kind of binoculars are good? i'm not sure whether i will get the telescope or the binoculars now. i really don't want to see upside down naked people. maybe if the person likes their gift this year i can upgrade them to a nice telescope next year.
posted by alicila at 11:28 AM on July 17, 2004

what kind of binoculars are good?

More or less standard 7x35 or 10x50 will be fine.

You can escalate up to 20x80 or 20x100/25x100 if you feel like it. At those sizes though, they're going to be big and unwieldy enough that you'd want them on a tripod.

For your proposed uses of *ahem* snooping-lite and looking at stuff like the moon, I don't think that's what's wanted though. A spotting scope will do better for that, since you can swap out eyepieces or pop in a Barlow lens to alter magnification, and you're paying for one good optical assembly instead of two.

Looking around, there are 4" and 5" (if you look used) Maksutov-Cassegrain spotters out there in your price range. That'd be what I'd do; refractors are going to be a bit big and unwieldy to put on the balcony or in a cramped urban apartment. Something with an aperture that size might double as a good intro astronomical telescope too if you take it someplace with dark skies.
posted by ROU_Xenophobe at 12:08 PM on July 17, 2004

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