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Hobbes
2002-Oct-24, 11:39 PM
Hey folks, I'm going to either get a telescope, or steal my dad's from him. So, I was wondering if anyone has any advice for buying a "first telescope", and some places to go to learn to use it. I don't want any of the whistles and bells on it (unless my pop gives me his, in which case I'll be stuck with what it's got). And any star-gazing advice anyone has would be welcome too. Thanks guys, and wish me luck /phpBB/images/smiles/icon_smile.gif

Superstring
2002-Oct-25, 12:06 AM
Here are a few good sites for selecting various telescopes.

http://www.discounttelescopes.com/telescopes.asp

http://www.telescopes.net/

http://skyandtelescope.com/howto/scopes/

All of these sites are good to use if you are just starting out in picking. I strongly reccomend the Celestron NexStar series, as those are of very high quality, though the price may not be the lowest. If not, any Celestron brand would be good, as well as Meade. Any other brand I do not reccomend as those two are among the best you can find.

I may have a few more links, let me know if you need any more. Hope this helps.

ljbrs
2002-Oct-25, 01:25 AM
Dobsonians (a/k/a Dobs) are great beginners' scopes. The prize-winning (Sky & Telescope a few years back) SkyQuest Dobs made and sold by Orion are very reasonably-priced. You can mount a Telrad on these scopes, equip yourself with Finder Charts books (which are used with the Telrads), and finding objects can be a snap.

The Fall 2002 Orion catalog cites the XT6 Dob for $329, the XT8 Dob for $449, and the XT10 Dob for $649. This does not include extras (which can be purchased separately). I forget what the Telrad and the Finder Charts (bought at other sites) sold for, but they are reasonably priced and a cinch to use. However, the usual Dobsonian telescopes are HEAVY! I bought an Orion XT8 Dob for my stepson's young daughter (and family) and included a Telrad and the four books of finder charts made primarily for the Telrads. I also bought books about astronomy. They loved them. Also, they informed me that their neighbors drop over whenever they are out using their Dob.

Then again, nice telescopes make great conversation pieces!

ljbrs /phpBB/images/smiles/icon_wink.gif /phpBB/images/smiles/icon_wink.gif /phpBB/images/smiles/icon_wink.gif

JimB
2002-Oct-25, 01:29 AM
Here are some more sites include reviews and a little advice on how to pick a scope.
http://www.scopereviews.com/
http://www.cloudynights.com/
http://www.findascope.com/
http://members.tripod.com/irwincur/index.html

Some of the specific advice I can give depends on how much you're willing to invest, how often you'll observe, will you have to pack it up to travel to a dark site, and do you like the challenge of tracking down faint objects on a map or do you want to look at a lot of objects in a short time.

Clear skys

Hobbes
2002-Oct-25, 02:40 AM
Thanks for all your replies folks /phpBB/images/smiles/icon_smile.gif I just talked to my pop; he's going to give me his Meade 2045D. He said it's a 4.5 inch Cassegrainian... whatever that is. Uhh, yeah, could someone tell me what that is??? So I guess I won't need a whole lot of help picking a scope. Now I need to figure out how to use the thing... heh heh... Am I going to need anything else? Star atlas, etc...?

The Bad Astronomer
2002-Oct-25, 04:17 AM
Read my page about first-time 'scope buyers (http://www.badastronomy.com/bitesize/scopefaq.html).

Wally
2002-Oct-25, 11:08 AM
Hey there Hobbes. A Schmitt Cassegrain telescope (SCT) is one that folds the light path within the body of the scope before reflecting it back out thru a hole in the back of the scope to the focal plane. This allows for a long focal length (thus higher focal ratio) in a short, portable tube. Rather than a 6 or 7 foot tube, you get the same FL from a 2 foot tube. It's considered one of the most portable (for the aperture) scopes around for that reason, and is generally considered a good, all around scope for general viewing of all types.

That said, please read all the sites provided in the responses above. It's best to study up on all the different types of scopes, find out their strengths and weaknesses, etc. Also, if you don't have a pair already, get some binocs (like 10x50's or so). I highly recommend you spend your first several nights with nothing but the binocs, a star chart and either Turn Left at Orion or Nightwatch. This is the best way to get started in astronomy, in my opinion. Wally

Hobbes
2002-Oct-25, 03:39 PM
Thanks Phil, I'll check that page out. Wally, does a SCT have any significant weaknesses? Also, can I get either of those titles at a regular bookstore? Or do I have to order them somewhere?

aurorae
2002-Oct-25, 04:24 PM
On 2002-10-25 11:39, Hobbes wrote:
Thanks Phil, I'll check that page out. Wally, does a SCT have any significant weaknesses? Also, can I get either of those titles at a regular bookstore? Or do I have to order them somewhere?


Turn Left at Orion and Nightwatch are usually available on the shelves of the larger book stores (like Barnes and Noble, or Borders) but not at some of the smaller ones (like the typical Waldenbooks or BDaltons in the malls) because they don't have enough shelf space left for science after all the pseudoscience books they have to carry.

You can also find those two books at your local library.

Or you can order them online at Amazon or at my favorite place, http://www.powells.com/

I agree that they are both great books for beginners with a new telescope.

Edited to mention that the Nightwatch we are referring to was written by Dickenson. There are other books with the same title.



<font size=-1>[ This Message was edited by: aurorae on 2002-10-25 12:26 ]</font>

Atko
2002-Oct-26, 01:01 AM
I'd agree with Wally about the binocs - much easier and more managable for viewing. I remember as a kid sitting out in the garden on a summer's night with my dad's binoculars, a jug of iced orange juice and a small paperback about astronomy which had star charts in the Appendices. It was the beginning of a love affair that's lasted thirty years.
/phpBB/images/smiles/icon_smile.gif

Hobbes
2002-Oct-28, 08:44 PM
Thanks for all the information folks; I've got more than enough to get started. Hopefully by the end of November, I'll have joined the ranks of the horde of amateur astronomers populating the globe. Thanks again,
Hobbes

Gambit
2002-Oct-29, 10:19 PM
::holds up a cross:: Repent, heathens! There is none better than the almighty Maksutov!

Kaptain K
2002-Oct-29, 10:59 PM
On 2002-10-29 17:19, Gambit22 wrote:
::holds up a cross:: Repent, heathens! There is none better than the almighty Maksutov!

Better at what? Soaking up $$$$/inch of aperture?

Atko
2002-Oct-29, 11:18 PM
See Hobbes - now you started a war, and already it's based on religion and economic inequality - darn it man, be careful what you post!

Russ
2002-Oct-29, 11:21 PM
On 2002-10-25 11:39, Hobbes wrote:
(snip)Wally, does a SCT have any significant weaknesses? (snip)


Since I didn't see anybody give you a direct answer to this question, and I'm a SCT bigiot, I'll take a shot at ansewering.

No there are no significant weaknesses in an SCT. But that, like anything, is a subjective evaluation. I have a Meade LX-200 and I LOVE IT! They have some really nice characteristics. 1) They give you a lot of focal length for the size/weight. 2) They tend to not need colomating as much as Newt's & Dob's 3) They are cheaper per unit of aperture than Refractors with (IMO) comperable image quality.

The only down side I can see is the pricing. While they are way cheaper than a refractor of equal aperture, they are WAY more expensive than a Dobsonian of equal aperture. Mine is a 10" and I have about $4K in my rig. That includes the scope, eye pieces & filters, barlow, dew shield and heater, Sun filter, and packaging for everything. I hope this helps. /phpBB/images/smiles/icon_biggrin.gif

Gambit
2002-Oct-30, 03:08 AM
Catadioptrics generally have 3 reflecting surfaces, so you may lose some light if you have low quality optics.

And Maks rule! Of course, nowadays only smaller aperture Maks are avalible, which is why you can't really do a straight comparison on a 10" Mak and 10" SCT. Let's hope that the Maksutov legacy will not remain limited to above-aberage planetary observers.

Hobbes
2002-Oct-30, 04:52 PM
Thanks Russ, I was hoping I wouldn't have to post the question again. I found out the model number of the telescope my pop is giving me. It's a Meade 2045 something... yeah, and it's got a 4.5 inch primary.... lens? mirror? Can't remember (sheepish grin). You know anything about that particular model? Dad bought it back in the early nineties for an eclipse cruise we went on.

Russ
2002-Oct-30, 05:43 PM
On 2002-10-30 11:52, Hobbes wrote:
Thanks Russ, I was hoping I wouldn't have to post the question again. I found out the model number of the telescope my pop is giving me. It's a Meade 2045 something... yeah, and it's got a 4.5 inch primary.... lens? mirror? Can't remember (sheepish grin).
Aperture is the word you're looking for there.


You know anything about that particular model? Dad bought it back in the early nineties for an eclipse cruise we went on.


I appologize, I don't know anything about that model. If it's a Meade, it's probably good. There are a couple of ways to test the quality of the optics. I'd recommend that you locate and join your local astronomical society (club) and let the "grey hairs" evaluate it. They'll probably be able to teach you how to use it to best advantage.

PS - "grey hairs" are the folks that have been in the hobby for a long time and know everything there is to know. They do not, necessarily, have grey hair. /phpBB/images/smiles/icon_biggrin.gif

Russ
2002-Oct-30, 05:45 PM
On 2002-10-29 22:08, Gambit22 wrote:
Catadioptrics generally have 3 reflecting surfaces, so you may lose some light if you have low quality optics.

And Maks rule! Of course, nowadays only smaller aperture Maks are avalible, which is why you can't really do a straight comparison on a 10" Mak and 10" SCT. Let's hope that the Maksutov legacy will not remain limited to above-aberage planetary observers.


Everybody is entitled to their opinion. Even if it's wrong. /phpBB/images/smiles/icon_wink.gif /phpBB/images/smiles/icon_lol.gif

Hobbes
2002-Oct-30, 07:13 PM
Thanks a lot for the help Russ. Also, I'll refrain from joining the war until I know more about telescopes. However, I understand that apochromatic refractors blow anything of equivalent size out of the water....

Russ
2002-Oct-30, 09:02 PM
On 2002-10-30 14:13, Hobbes wrote:
Thanks a lot for the help Russ. Also, I'll refrain from joining the war until I know more about telescopes. However, I understand that apochromatic refractors blow anything of equivalent size out of the water....

/phpBB/images/smiles/icon_lol.gif /phpBB/images/smiles/icon_lol.gif /phpBB/images/smiles/icon_lol.gif The operative word here is "...equivalent size...". In my club there is a fellow who has a 6" apo. refractor. It's a beautiful instrument to say the least. That's the good news. The bad news is...he has to have an extended box econoline van to haul it and the tripod around, it weighs about 100 lbs., the German equitorial mount it takes weighs about 200 lbs., it takes him about 45 minutes to set it up, and, finally, it cost as much as I paid for my 10" scope & kit and the Chevy Blazer I use to carry it around.

After all of that, when we both are pointing on Saturn, for example, I can seen no difference in the quality of the image. Ya pays ya moneys 'n ya takes ya chances. /phpBB/images/smiles/icon_wink.gif

Hobbes
2002-Oct-30, 09:37 PM
On 2002-10-30 16:02, Russ wrote:
/phpBB/images/smiles/icon_lol.gif /phpBB/images/smiles/icon_lol.gif /phpBB/images/smiles/icon_lol.gif The operative word here is "...equivalent size...". In my club there is a fellow who has a 6" apo. refractor. It's a beautiful instrument to say the least. That's the good news. The bad news is...he has to have an extended box econoline van to haul it and the tripod around, it weighs about 100 lbs., the German equitorial mount it takes weighs about 200 lbs., it takes him about 45 minutes to set it up, and, finally, it cost as much as I paid for my 10" scope & kit and the Chevy Blazer I use to carry it around.

After all of that, when we both are pointing on Saturn, for example, I can seen no difference in the quality of the image. Ya pays ya moneys 'n ya takes ya chances. /phpBB/images/smiles/icon_wink.gif



Alrighty then.... An econoline extended van huh? And cost as much as yours plus your vehicle? Hmmmm.... Ok, maybe when (if) I get rich. Ok, another question. Is 4.5in of... aperture respectible for a starter SCT scope? Cause I'm stuck with this one for now.

Gambit
2002-Oct-31, 01:56 AM
Wars?What wars?
And you're absolutely right Russ. Everyone's entitled to an opinion, even if it wrong. Even those who believe that the SCT is better than the Mak.
Hobbes, 4.5 inches is actually not a lot. I'd recommend at least 6 for decent light gathering.

Hobbes
2002-Oct-31, 02:53 AM
Well, even if 4.5 inches isn't a lot, I'm still stuck with this scope for awhile. I'll probably get a ten incher next, but I guess this one will have to do while I'm a beginner. But thanks for your input though. And you know what war; I'm only a rank amateur, but I can see that there's a lively ongoing debate about the best kind of telescopes. /phpBB/images/smiles/icon_smile.gif
I was also thinking about getting a semi-expensive pair of binocs for astronomical viewing, any brand ideas? I'll probably go with Orion unless anybody warns me against it. Something 10*50 or bigger, with a tripod.

Kaptain K
2002-Oct-31, 01:00 PM
Hobbes,
The "best" telescope is the one that is used. In other words, a 4.5" that goes out every clear night is a better scope than a 12" that stays in the closet.
Three things to remember:
1) A scope is only as good as the mount it rides on.
2) Good eyepieces are worth the cost.
3) Magnification is not as important as light gatering power and resolution.

Wally
2002-Oct-31, 06:13 PM
On 2002-10-30 21:53, Hobbes wrote:
Well, even if 4.5 inches isn't a lot, I'm still stuck with this scope for awhile. I'll probably get a ten incher next, but I guess this one will have to do while I'm a beginner. But thanks for your input though. And you know what war; I'm only a rank amateur, but I can see that there's a lively ongoing debate about the best kind of telescopes. /phpBB/images/smiles/icon_smile.gif
I was also thinking about getting a semi-expensive pair of binocs for astronomical viewing, any brand ideas? I'll probably go with Orion unless anybody warns me against it. Something 10*50 or bigger, with a tripod.


Orion's got a great selection of binocs, and I think you'll be happy with the 10x50's, and they're not even semi-expensive! You can actually use them w/out a tripod if you wish with pretty good success, especially if you lay back on a chair and brace your elbows on the arm rests.

Ok, now back to the SCT wars /phpBB/images/smiles/icon_smile.gif Russ, you forgot to mention that the central obstruction that holds the secondary mirror reduces overall contrast compared to a high quality refractor (BUT. . . like you I'm a bigot myself as the proud owner of an LX90!).

Also, someone above mentioned 3 mirrors in an SCT??? Last I counted, there were only 2 (if you don't count the diagonal). Guessing they were counting the corrector plate as a mirror though. . .

Hobbes
2002-Oct-31, 07:11 PM
You know, if one had the funds, it would be a blast to build a giant dobsonian into a large van or truck, or even a motorhome. It would be so cool to go puttering around with a huge scope in the back of your vehicle. Kinda like a mobile observatory....

2002-Oct-31, 09:19 PM
Every time the light is reflected, a percentage of it is lost. Since the diagonal is a mirror, most catadioptrics have 3 mirrors.
And I whole heartedly agree that the best scope is the one you'll use the most. However, I also advise everyone to get the largest telescope that they can possibly use. I understand that the 4.5 is a gift Hobbes, but have you considered making your own telescope?

Hobbes
2002-Nov-01, 01:42 PM
Yeah, but I need to learn a heck-of-a-lot more about astronomy before I try to build my own. But yes, I'd love to build a gigantic dobsonian. You know, the kind that requires a ladder to reach the eyepiece, and a 53' semi-trailer to haul it around in.

Hobbes
2002-Nov-01, 07:56 PM
Hey, got another question for anyone who may know... I'm going to build a dobsonian from plans I found online, but I'd like to build the secondary mirror supports a bit stronger than the plans call for. What kind of material would be the best for the supports? I was thinking of rigid plastic of some sort.

And also, will increasing the number of supports from three to four interfere with the light-gathering ability of the scope in any noticable way?

David Hall
2002-Nov-01, 08:44 PM
On 2002-11-01 14:56, Hobbes wrote:

And also, will increasing the number of supports from three to four interfere with the light-gathering ability of the scope in any noticable way?


Actually, as I understand it, 4 vanes are better than 3. If you look at any high-quality commercial scope, you'll see they they use 4 vanes. This is because the image reversal of the primary mirror doubles up the interference pattern of the vanes. So a 3 vane support will actually create 6 rays of interference. But in a 4 vaned system the doubled shadows from the primary fall in the same pattern as the vanes themselves, and therefore the pattern remains at 4 rays of interference. So the extra vane actually improves the image.

edit:

Ok, I looked around, and my memory was a bit off. The big problem with 3 vaned "spiders" is the diffraction pattern they cause when focusing on stars and the like. But 3 vanes are a bit better in light gathering power.

Here's a rather technical PDF paper on the effects of difraction patterns:

http://imaging.creol.ucf.edu/publications/Spider_Diffraction.pdf

And here's a quick page with some suggestions on how to build a spider.

http://w1.411.telia.com/~u41105032/spider/spider2.htm

Good luck!


_________________
<font size="-1">PLEASE NOTE: Some quantum physics theories suggest that when the consumer is not directly observing this product, it may cease to exist or will exist only in a vague and undetermined state.</font>

<font size=-1>[ This Message was edited by: David Hall on 2002-11-01 16:13 ]</font>

2002-Nov-01, 10:03 PM
3 vanes can be mounted with an angle to reduce the diffraction spikes and keep the light gathering abliity the same. And it is not the number of vanes, but their curvature that minimizes spiking.