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Jim_McBrearty
2002-May-05, 06:51 PM
Right, I've been into Astronomy for ages, but only got upgraded my binoculars 2 years ago to purchase a telescope. (Actually it was my Dad who got me it.)

It's a basic "Goldline" refractor, which has a max power of around 175, and, it's getting long in the tooth. I've been saving for a computer upgrade for a while, but am now considering getting a decent reflector; a big decision for a student like me.

Now, there are two i've got it down to, My Dad insists on getting one with an "Equitorial Mount"; but that one costs 30 squid more.

I have a dilema: I've never used one of these fancy mounts before, but he keeps telling me they're better: Since he's been using telescopes longer than I have, I tend to go with his judgement.

Help! What should I do! And what is the benefit of one of these equitorial mount thingies anyway, my Dad tends to come out with Physics styled mumbo-jumbo about earth rotation and tracking objects: Maybe the bad astronomer could do a piece on the site about wtf this mount is? /phpBB/images/smiles/icon_smile.gif

All help appreciated...

Jim

_________________
There's only one Harry Kroto! One Harry Kroto! [repeat]

<font size=-1>[ This Message was edited by: Jim_McBrearty on 2002-05-05 14:53 ]</font>

MHS
2002-May-05, 11:10 PM
I would recommend you to buy a telescope with an equitorial mount too. I have one myself and it's pretty handy. The only thing you have to do to track a star or planet or whatever is aiming one of the system's axes at polaris. Then you can track the object with the use of only one hand. When you put a little motor on the tracking system that causes the ax to spin around in 24 hours you can make photos that need a long(er) exposure.

roidspop
2002-May-06, 03:43 AM
MHS is right. With the equatorial mount, you get it lined up and twiddle one knob to track something. With the other rig, you have to twiddle two and it's a nuisance. You tweak this one a little and the object vanishes from the eyepiece, so you go hunting all over with both knobs and get hopelessly lost and say something unpleasant and pack it all in. With the equatorial, you're only half as lost usually. Not to go on too long here, but lining up your spotter scope so it can actually be used is one very important job...I think it's the blackest of magic, but if you don't get it right, you can use your telescope for an umbrella stand for all the good it'll do you. Do it in the daytime, sighting your telescope on a nearby object (maybe not your neighbor's bedroom window), lock the axes, and then fiddle that spotter scope in, two screws at a time in opposite directions, until its crosshairs are smack on the thing you've picked out. Now you'll be able to put the crosshairs on a star, look through your low power eyepiece
and the object will be where you can actually find it.

Now, somebody who really knows astronomy will pin my ears back.

Good Luck!

ljbrs
2002-May-06, 05:06 AM
Regardless, telescopes also make great conversation pieces whenever you throw a party. The only problem is that if the guests get inebriated, they might want to use your telescope as a place to dump unwanted and unfinished drinks, etc. Telescopes also make great spittoons, so be careful about whomever you invite to your parties. Inviting *clowns* can ruin your evening. In any case, it might be a good idea to move your *conversation piece* to a more secure location during festivities.

Go for the equatorial mount. Altazimuth mounts are a big bother to use (as I well remember from my younger and less-wise days).

ljbrs /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_smile.gif /phpBB/images/smiles/icon_wink.gif /phpBB/images/smiles/icon_rolleyes.gif /phpBB/images/smiles/icon_confused.gif

ljbrs
2002-May-06, 05:14 AM
Oh, yes, some people dispose of their stale gum by securing it on the undersides of tables, etc. These same clowns might wish to affix their *used* gum to a portion of your telescope. Check your guest list for clowns. It might be better to secure your nice toy in a safe location (preferably *locked*).

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David Hall
2002-May-06, 06:38 AM
Actually, I disagree with the posters above in one respect. It's hard to recommend anything to another without reservation because you don't know what the other person's needs or wants actually are. Equatorial mounts are great of course, but it all comes down to how you are going to use the scope.

The pro side of equatorial mounts is the ability to track an object easily. The motion of the mount directly counteracts the rotation of the Earth. An equatorial is a necessity if you are going to do astrophotography and very convenient otherwise.

On the con side, not only are they more expensive, but they are also harder to use. You have to make sure they are correctly lined up with the poles or else objects will drift out of view. This isn't as bad with todays electronic controllers, but it's still a bit of a hassle. Equatorials can also put the eyepiece in awkward positions when looking in certain directions. In addition, you need to make sure the mount is sturdy enough for the scope, especially if the scope is big. A lot of mounts aren't really strong enough for the scopes they come with.

As for alt-az mounts, there are several designs, and the most common is the Dobsonian. But all are simply "point and shoot" type configurations. On the pro side, they tend to be cheap, and they are usually easy to use also. No need for fancy alignments or setups. Just take it outside and aim the scope where you want to look.

On the con side, you can't track with them. It is possible to add on motorized trackers that can make them perform almost as well as a equatorial (at additional expense of course), but they'll never be quite as good. Without such a device, you have to constantly keep realigning them as the objects you view slip out of the field of view.

So it depends on what you want to do. If you just want to take the scope outside now and then to check out the sights, or are more concerned with portability and quick setup, then go for an alt-az. If you want or need good tracking ability and aren't concerned about the complications of setup or the expense, then go for an equatorial.

I personally prefer equatorials because I don't mind complicated things. I like to set everything up and then not have to worry about it later. But, as is often pointed out here, the best scope (or mount) is the one that you will use the most. I say make that your number one priority. Good hunting.

Jim_McBrearty
2002-May-06, 07:42 PM
Thanks for all the help! Woah - This really is the place to come to cut through all the advertising **...

I've decided to go for the Equitorial mount, particularly since it comes with a camera adapter: If I get good shots of anything i'll try to scan them and make a webpage with them.

Looking forward to planning out my new home on the Plato uplands with this new scope /phpBB/images/smiles/icon_smile.gif

Tim Thompson
2002-May-06, 10:06 PM
Jim: I've decided to go for the equatorial mount, particularly since it comes with a camera adapter: ...

If your aim is to photograph things that aren't really bright, then you will need an equatorial mount. You will also need a good clock drive, so the telescope will track during the exposure and avoid smearing the image. But I have seen pretty good pictures from digital cameras that are just held up to the eyepiece by hand, especially of the moon.

However, if you are not going to do photography, then I think the equatorial mount is too cumbersome & too expensive. With a Dobsonian style alt-az mount, in a simple box construction, you can be doing astronomy within one minute of stopping the car engine. The advantage of the equatorial mount is that it's easier to track by hand if you use high power. But I find that high power is usually uncalled for unless the seeing is really good. Otherwise, at low & moderate power, tracking with an alt-az mount is no more difficult than with an equatorial, as long as the movement isn't too stiff. Just a little nudge and the target is back. If the power isn't too high, it takes a while to drift across the field of view.

It really does depend on what you want to do. But I can tell you I am surrounded by astronomers who have had equatorials, refractors & reflectors, and computer controlled telescopes. And one by one they are dropping like flies, and showing up with really expensive, huge aperture (20 inches or more) Dobsonians. They are a bit more work to set up, but once you get used to moving around in the sky, the views are just too much to ignore.

ljbrs
2002-May-07, 02:38 AM
I had completely forgotten about the Dobsonian which is a snap to use. It might be good to have a Telrad (a kind of finder scope) or something like it and some easy-to-use books of *Finder Charts* such as those published by *Sky Spot*: *The MESSIER OBJECTS,* Volumes 1 and 2; *Bright Telescopic Objects*; and *Overlooked Objects.* There may be more since I last purchased mine.

The Alt Azimuth controls for a refractor telescope like the one I had long ago made it impossible to follow anything without making constant adjustments in a zig-zag pattern. The telescope I owned could not be controlled without twisting one and then the other control in an attempt to get a smooth movement when following a somewhat quickly moving object across the sky (long before the time of the Space Shuttle). The alt azimuth controls for my refractor were very frustrating to use. That telescope was bothersome and was foolishly bought in a fancy department store. Dumb! Do not buy *department store telescopes*. You probably will be very sorry if you do. Try specialty stores which deal more seriously with astronomy. Look in *Sky & Telescope* or in *Astronomy* (magazines) for some ideas. Visit and/or join an astronomy club and members are usually glad to show off their toys. Sky & Telescope has a long list of astronomy clubs throughout the world. There ought to be an astronomy club in your vicinity. Visit them first before joining.

Have fun.

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Gsquare
2002-May-08, 03:27 AM
On 2002-05-06 15:42, Jim_McBrearty wrote:
I've decided to go for the Equitorial mount, particularly since it comes with a camera adapter:


Good choice, Jim. It's always good to follow your Dad's advice, especially if he's the one shelling out the squids./phpBB/images/smiles/icon_smile.gif

But if you want to really have a good mount tell him you want to have the kind they use on the Hubble tele. /phpBB/images/smiles/icon_lol.gif

G^2




<font size=-1>[ This Message was edited by: Gsquare on 2002-05-07 23:30 ]</font>

David Hall
2002-May-08, 03:59 AM
I'm under the impression that alt-az mounts, even those with motorized drives, are not suitable for long duration photography. They may be able to track the object, but the nature of the mount induces a rotation of the field of view. Any exposure more than a few seconds will thus have streaking. Is this correct?

Trish
2002-May-08, 06:57 PM
Well, for the Dob mounts, you'll have to purchase something used. I've been looking into a 6-8" reflector for my kid and I. Unfortunately, most of the scopes I've looked at are no longer sold from the maufacturer with the Dob mount. Everything now comes standard with the equatorial mount. It's not a matter of personal preference as much as what's available.

Jim_McBrearty
2002-May-08, 09:16 PM
Well, I don't know what the general opinion is, but my scope is brilliant /phpBB/images/smiles/icon_biggrin.gif. Just ashame that there's a lot of light pollution round here, and I have to go a few miles to get the real benefits of it.

As for the photos, I haven't tried any yet, but again, i'll post em If I do.