Questions about Telescopes

Factual Questions
1

I’d appreciate if anyone could answer any of these questions for me. THANKS!

[ul]
[li]How much does a good one cost?[/li][li]What’s the best one I can get for under $200?[/li][li]What should I be looking for when buying them?[/li][li]What do all the specs stand for (Moon Filter? Concave Objective Mirror? Focal Length? Equatorial Telescope Mount? Etc.)[/li][li]Is this something that someone who likes to look at the starry sky like?[/li][li]Is Southern Michigan an OK place to use it?[/li][li]On a side note, how much does it cost to name a star after someone?[/li][li]would that someone be likely to be able to see that star with the telescope?[/li][/ul]

2

I can’t answer the telescope questions, but the Master has spoken on the star naming point; you can hear more directly from the IAU and from this site.

3

An in-law’s hobbyist opinions:

  • The best cheap ones are the “stubby” refractors, around F/6. Meade and Orion both make them.
  • They cost $300-$600, you want an objective lens at least 100mm dia.
  • The reason that the stubbies are better is that the mounts of cheap telescopes tend to be flimsy and have lots of mechanical play, but the stubby telescopes are lighter and less susceptible to such problems.
  • Ideally you want an equatorial mount with a clock drive included, or at least an equatorial mount that a clock drive can be added onto later.
  • A refractor is also useful for looking at terrestrial objects. There are a couple cheap stubby Newtonian reflector scopes out, but their mirrors are crap (he says) and they aren’t good for looking at earth-bound things (which is a common use of telescopes by sort-of enthusiasts).
  • There are other types of small scopes like Schmidt-Cassegrains and Maksutovs that technically give better images, but they are lots more expensive than regular (cheap) refractor telescopes.
    ~
4

An enjoyable astronomical telescope could cost a few hundred dollars. Two hundred might be tough, but five hundred would give you many choices.

Some details that you might care about:
Astronomical telescopes need nice mounts and clock drives to follow astronomical objects as the earth’s rotation makes them move across the sky. If you are just looking around at large objects like the moon or star clusters or large nebulae, you can see a little bit without the clock drive.
Filters aren’t important for a beginner on a budget.
To see planets, you want lots of magnification and a very good stable mount, but the diameter of the telescope is not so important.
To see the easier galaxies and gas nebulae, you want a large aperture but not lots of magnification. You probably want a good stable mount but not necessarily the costliest.
Telescopes with mirrors but no big lenses give you the biggest aperture for the money. These include Newtonian and Cassegrain designs. Telescopes with big lenses are very expensive.

If you like loooking at the starry sky and want to spend $200, you’d probably have a great time with some nice binoculars, especially if you got ones with big lenses.

5

If you don’t need polar mount (nice, but not critical unless you are doing photography), the best bang for the buck is a Dobsonian mount. (That way all your money goes for the optics and not the mount)

(like http://www.telescope.com/cgi-bin/OrionTel.storefront/3d72173e0f04792eeacec0a80a6506c1/Product/View/A031 )

Not trivial to transport however. (I have the older revision of the 8 inch version, and can transport it in my Geo Prizm)

Since those star naming “services” have no official bearing whatsoever, you could name Vega, Sirius, or Betelgeuse and then you wouln’t even need a telescope to see them.

Note IMHO that most stars are BORING in a telescope, they are still points. (Though splitting doubles can be fun). The cool things (again IMHO) are planets and nebulae.

Brian

6

I mostly agree with DougC…

Two things, though:

  1. an equatorial mount is nice, but can be a pain in the butt to set up… and is NOT necessary (depending on what you are doing, that is…).

  2. a clock drive is only needed if you are planning to take photographs through the telescope. They can be fairly expensive… so if there are no plans for astrophotography, skip the clock drive. Also, a clock drive is useless unless the equitorial mount is set up JUST right. Any error in doing this will really screw up your picture (see point number one, above).
    It sounds to me as if this telescope will be a gift for someone else. Is this so? If so, does the person in question know much about telescopes? You might want to consider something like a gift certificate at a telescope store if this is the case, so that the giftee can choose what they want… I wouldn’t want Astrogirl to buy me a scope, because she doesn’t know anything about it, OR my astronomy habits (which can be a big factor in the type of scope to buy).

Some factors to consider:

-will there be any astrophotography?
-what are the viewing habits? Planetary observation, deep space objects, or into the next door neighbor’s daughter’s room? Or all of these?
-is the person a newbie scope owner? (high possibility of disappointment if the person has never looked through a scope before… things don’t necessarily look like the pictures you see from NASA.)
-where and when will the scope be used? (portability and ease of set-up issues here)
-other factors I am forgetting, I’m sure.

Here’s a good site for telescope buying tips: Err… here!

Now, to answer a couple of the Qs from the OP:

A moon filter is a filter that screws in to (usually) the end of the eyepiece… the moon is pretty bright, and at times you need a filter to cut down on the brightness so you can look at it through the scope. Similarly, you will find sun filters so you can look at the sun without burning a hole in your retina…

A concave objective mirror is the main mirror in a Newtonian-type reflection telescope. It is, er, concave. The light in this type of scope passes down a tube, and is bounced off the concave mirror to be reflected and focused on the eyepiece.

Focal length is basically the length of the telescope body. Longer focal length is better for planetary-type observation, shorter is better for nebulae/deep space objects (warning! Vastly over-simplified! But gimme a break… I been drinking!)

An equitorial mount refers to the mount that connects the telescope to the tripod (or other base) that it sits on. An equitorial mount aligns the telescope with the axis of rotation of the Earth, so that as you move the scope, it traces an arc that follows the curved path of stars/planets/nebulae, etc. as the Earth revolves(did that make sense?). Can be a bear to set up correctly (as I said earlier) and isn’t really needed unless you are planning to take long exposure photos (long exposure here meaning more than a few seconds… without an equitorial mount, the star or whatever will move and the picture will be blurry… see below in regards to the clock motor drive).

A clock motor drive is used in conjunction with an equitorial mount to move the telescope along an arc, so that the star or whatever stays perfectly (ideally… but people tend to sneeze, pass gas, trip over the tripod going to get a beer…) still in the center of the feil of view. This allows you to take long-term photos of astronomical objects. Not really needed unless you plan to take photos.

Errr… maybe. Depends how interested the person in question is in astronomy. A telescope can be as easy to use as carrying it out into the yard and taking off the lenscap, or can be a real bear to haul out into the desert, let all the mirrors/lenses equalize in temperature for an hour, set up the tripod, mount the scope and set the equitorial mount to align as perfectly as possible with the axis of the Earth, look up and find that clouds have moved in and you have wasted an evening that might have been spent better watching TV and scratching your crotch. YMMV.

Sure! Depending on what you want to do with it, of course… A lot of light pollution from a nearby city will degrade things a bit, of course… are you near a big city?

Dunno… but I think someone above answered this one.

Err… depends. Where is the star? What is its magnitude? Where are you looking from? What kind of scope did you go with? How drunk are you (maybe you can see two of it!)… etc. So the answer here is an unqualified maybe.

Hope that helps!:wink:

7

General agreement with your post, Napier, but I disagree a bit with the above.

Filters are cheap, and sometimes VERY necessary when looking at the moon, and ABSOLUTELY necessary when looking at the sun!

And magnification degrades the image… the more you magnify something, the worse the image you see will be. It’s a bit of a balancing act, but for planets I have always found that lower magnification was preferable. Most of the objects that are observable with an amateur scope are best seen with lower magnification… I almost never use my higher mag eyepieces.

8

Oh! Ditto on the binoculars, by the way… that’s going to be one of my first purchases when I move out of Seoul!

9

All this sounds a bit complicated and expensive… Could you clear up a few things for me?

[ul]
[li]“stubby” refractors?[/li][li]Objective lens?[/li][li]Refracter?[/li][li]Newtonian reflector scopes?[/li][li]Polar Mount?[/li][li]Dobsonian mount?[/li][/ul]

And some clarification:

[ul]
[li]I’m not looking to spend more then $200 on her this time. My car has broken repeatedly lately, and I am a little strapped for cash. $200 is being generous, so I can’t stretch much on the price.[/li][li]I think I am going to scratcht the star naming idea. Don’t want to promote the exploitation of America’s ignorant.[/li][li]Neither of us have ANY star-gazing experience, aside from just looking up late and night and saying “Those are so cool,” and staring at the for an hour or so.[/li]li There will not be any astrophotography, as I had never heard of it till you mentioned it.[/li]li Will be used mostly for “cool stuff” I supposed. I don’t think she has any preferences on what to look at, as long at it’s pretty.[/li]li We would both be qualified as newbie scope owners, if we become one.[/li]li Where are you supposed to use them? Bedroom? Outdoors? I dunno.[/li]li [Cleatus voice] No big cities round these parts neighbor! [/Cleatus voice] Bout an hour from Detriot, but that shouldn’t matter (right?), and she lives about 8 miles from the nearest small city (About 15K people… no skyscrapers)[/li][/ul]

I think I have answered and asked most things I was curious about. Please add if you think there is something else.

10

A Dobsonian mount is a type of “alt-az” mount. The two axes of movement are back and forth (parrallel to the horizon) and up and down (perpendicular to the horizon). The telescope tube is pivoted at its center of mass and the bearings give just enough friction that you can easily move it but will stay put when you let go. (follow my earlier link to see a picture)

Perhaps instead of a telescope you could get other astronomy stuff:

A book. H.A. Rey’s (yes the Curious George guy) The Stars, a new way to see them is a good one.

Desktop planetarium software. I like Starry Night (avallable at www.space.com ), but I am biased since I helped beta test it.

As mentioned before, binoculars. These will let you see the moon, the Pliedes (star cluster), Andomeda Galaxy, etc.

Brian

11

You might want to check out this site. It’s by the SDMB’s very own resident astronomer, The Bad Astronomer.

Don’t let the name fool you. Phil is a professional astronomer and the site is set up to help first-time 'scope buyers.

Buying A Telescope?

12

I have nothing new to add, but wanted to state again that binoculars are the best first telscope. Why?

  1. Binoculars are great for other things (sports, birdwatching), so if you give up on astronomy, you’ll still use them (unlike a telescope).

  2. Binoculars are portable and thus more likely to be used.

  3. Binoculars are easy to use and require no unusual mental maps (many telescopes flip images left/right or up/down).

  4. For any given dollar amount, binoculars will be of much higher quality than the correspondingly priced telescope.

  5. In order to use a telescope for astronomy, a person should have some familiarity with “the night sky”. Along with the good old naked-eye, binoculars are ideal for doing so.

Here are some helpful threads on similar topics:

Telescopes and Binoculars.

Telescope info …

Which telescope should I buy?

13
      • Well,
  • A refractor is the regular type of telescope with the big lens on the front end. Ideally, you want one with a lens at least around 4 inches across but they’re over the budget.
  • Stubby telescopes are, well, stubby. Amateur refractors have gotten stubby-er through the years. (the F/XX is the focal length, the ratio of length to lens diameter)
  • Just as an example: the Orion Transporter 70mm Min-EQ Refractor is one lower-price stubby refractor. (www.telescope.com) It has no clock drive, but accepts one. I didn’t find much below $200 total, and this one only has a table top tripod. The only cheap bare tripod that Orion seems to sell is their Traveltech tripod, which folds up real small but is probably fairly flimsy. Usually these small mouts can be attached to a regular camera tripod, ask Orion before buying to be sure.
  • I don’t know anything about that particular telescope, it is just one example of a cheaper stubby I found.
    -Before buying, search online (Google, forums+newsgroups) for problems it has!
    ~
14

Just to reiterate what others have said, if you’re new to astronomy and you want some exciting viewing experiences, get a set of good binoculars. You’ll see some amazing sights, and if you decide astronomy isn’t for you, you can use them for other things. Plus, they are highly portable and you can easily pack them on trips. Take them camping with you where there is no light pollution, and spend some time just lying in a sleeping back staring at the sky both with the naked eye and with your binoculars.

If you must have a telescope in that price range, you might consider the Edmund Scientific AstroScan. It’s a rich-field telescope, giving you a wide field of view more like binoculars. You can just cradle it in your lap and look at the sky or use its stand. If you must have a telescope, and you can’t spend more than about $200, I think it would be hard to beat this option.

Whatever you do, stay away from the cheap refractors. Most toy shops and ‘educational’ stores sell Refractors in the $80-$200 range, and almost all of them suck. The mounts are unstable, the focusing gears have backlash making it a chore to set up, and there is so much chromatic aberration that stars just look like rainbows. These types of telescopes have destroyed a lot of young people’s interest in astronomy.

15

The more I think about it, the more I think that maybe the Astroscan is what you might like. Until I looked at the first link, I didn’t realize that they had dropped in price so much. Here’s another review of it that gives some good details: AstroScan 2001 Review

16

The first piece of advice I’ll give you is to join an amateur astronomy club. Do this regardless of whether you buy a scope. They’ll host star parties where you can look through other folks’ scopes, and they’ll have plenty of advice for you. You should be able to find one near you through the Astronomical League.

Now, then. The only reason to use an equatorial mount is to be able to use a clock drive, and if you’re not doing photography, you don’t need a clock drive. Alt-az mounts are much cheaper, go with one of those. Specifically, Dobsonian mounts are very simple, very cheap, very sturdy, and pretty easy to set up as well. Without a drive, you’ll need to adjust the scope every so often to stay pointing at the same thing, but that’s not too difficult.

Do not ever buy a telescope from anyone who’s emphasizing how much magnification the telescope has. You buy a good scope, and then get an eyepiece for whatever magnification you want. The three biggest companies for amateur scopes are Meade, Celestron, and Orion, and they will all give you decent optics.

Presuming that the optics are good enough (they should be “diffraction limited”), the most important thing about a scope is the aperature, or diameter of the main optics. Bigger is always better. The only limiting factors on aperature are price and portability. At $200, you’re probably looking at the six inch range, or so.

Depending on your skills, you can also save a good deal of money by building the scope yourself. Typically, what you would do is buy all of the optics (primary and secondary mirrors and focusing assembly) from one of the above-mentioned companies, and put it in a tube and mount yourself (members of the local astronomy club will be able to help with this; see above). This will typically cut off about half of the price. You can also buy the tube already assembled, and just build the mount (a Dobsonian mount is very easy to build).

The Astroscan is a decent little telescope, but it’s essentially not upgradeable. It’s much easier to get accessories and such for a more conventional scope. On the other hand, the Astroscan sets up in about half a second, and is a cinch to use. Again, I would recommend that you look through several scopes before buying, and get some idea of how far you want to go with this.

17

I hardly have the expertise that many of these folks clearly do, but I wholeheartedly agree that binoculars are seriously underrated as stargazing implements. You can see a lot more with a decent (or even not-so-decent) pair than you might think…

Binoculars are also to have around on multi-person stargazing engagements - you can use them to actually see stuff while a couple of dudes try to figure out how to use the 'scope, argue over what to train it on, get confused, etc. :slight_smile:

The only thing I can think to add in the gift department is a Planisphere. I’m sure you can buy them wherever you get the 'scope, and I don’t think they’re that expensive. If you don’t know your way around the sky very well, these things can be dialed in to the current date/time - at which point they provide a pretty nice map of what’s really visible above the horizon.