Buying a Telescope

[Ginnie]

I'm thinking of buying a telescope.
Any advice on what a beginner should get?
This is the one I have picked out:

SKP13065EQ2 features a 5.1" paraboloidal mirror and beefier mount.
Its 650mm focal length and larger aperture allows for more magnifcation without loss of image quality compared to smaller aperture telescopes. This fine telescope continues to be our best selling telescope for beginning astronomers.
* 5.1" Parabolic Mirror!
* Sturdy Tripod
* Red Dot Finder!
* Easy to Set Up and Use
* Includes Quality Eyepieces!
* A complete kit - ready to go.
Price: $299 (Can)

Optional RA Drive
with Controller on sale
for $99.95 CA (Reg. 109.95)
www.kwtelescope.com/HomeFS.htm

There's a four inch like this one for $199 but I don't think you can hook up a camera to it. Also comes with only one eyepiece.

Do I get more bang for the buck by getting a Newtonian Reflector?
Or should I be getting a refractor?
Also, with a 5 inch reflector, will I get a good view of deep space objects like nebula's, galaxies etc?
Mind you, I am very much on a budget - after buying a new bass guitar a month ago, I don't think my wife will be pleased if I spend more than 300 dollars on this. The RA Drive would have to wait for now.

____________________________

[Al Johnston]

From what I recall of the advice given by Patrick Moore & the like, binoculars are the usual recommendation for someone starting out. As far as telescopes are concerned, I think reflectors are preferred to refractors: mirror size is the most important parameter, as that governs how much light it can capture.

[Ginnie]

I've used Binoculars before. But being that I prefer looking at the winter sky and it gets cold here in Canada, I can't hold them very still. I guess I could get binoculars that mount on a tripod?
But I'd rather invest in a telescope than buy another pair of binoculars plus a tripod.
In the past I did a winter of naked eye viewing and really enjoyed it. By February I had most of the sky figured out - most of which I forget now except for Orion, Big Dipper and the Pleides, plus some major stars (Sirius and such).
I'm a bit worried about how much I can see in my area, since I live in the middle of the city. On an average night, the Polaris is the only star I can see in Ursa Minor with the naked eye.
I'm bummed out right now because Comet Holmes has increased its brightness by 500,000 times on Oct. 31 and its been raining here every night since last Thursday, the clouds are really obscuring everything.

[Waspie_Dwarf]

ginniegatrit said:

I've used Binoculars before. But being that I prefer looking at the winter sky and it gets cold here in Canada, I can't hold them very still. I guess I could get binoculars that mount on a tripod?
But I'd rather invest in a telescope than buy another pair of binoculars plus a tripod.

You can buy a very inexpensive gizmo that allows a pair of binoculars to be attached to a camera tripod. A good pair of binoculars (with nice big objective lenses) will give you better bang for your bucks than a really cheap telescope.

A poorly made, cheap telescope can be a real disappointment.

However if you do want a telescope both reflectors and refractors have advantages and disadvantages.

Refractors tend to give better contrast. They also tend to be able to cope with higher magnifications. I know a lot of planetary observers like to used them.

Reflectors on the other hand are better if you are after deep sky objects such as galaxies and nebulae.

This site gives some good advice on telescopes: www.star.le.ac.uk/~dbl/ask/telescopes_faq.html

[Bob B.]

The simplest rule is that the right telescope is the one you’ll use the most. Deciding on type, aperture, and mount is mostly a function of what you want to use it for, where you’ll use it, and what your budget is. Do you want to mostly observe planets or deep sky objects? Will you observe from home or travel to a dark-sky observing site? Etc.

For deep sky objects you want to maximum aperture to collect as much light as possible. You also need a dark-sky observing site with little light pollution. If you live near an urban area, that might mean traveling to a site away from city lights. You therefore need something transportable. Anything in your current budget will be small enough to fit in your car, so that is not a big issue for you.

The most aperture for the dollar is a Newtonian reflector on a Dobsonian mount. For $300 you should be able to get a 6” telescope. An 8” is better but that might run about $400. The problem with Dobsonians it that they have to be moved in two axes to track celestial motion, which makes them cumbersome to use with high magnifications. Dobsonians are a good way to affordably maximum aperture, but I wouldn’t recommend one if you plan to use it mostly for planets.

For planets, where high magnifications are used, you’ll probably want something on an equatorial mount that can easily track the motion of the planets across the sky. Perhaps you could also get one that is motorized. Don’t skimp on the mount – get something that is strong and stable or you’ll be sorry. An equatorial mount is more expensive than a Dobsonian, so you’ll have to compromise on the optical tube by getting something of smaller aperture.

Planets are bright so you don’t need as much aperture, however a large aperture also means greater resolution. Refractors are generally considered better for planets because they don’t have the center obstruction of a secondary mirror, which gives them a higher contrast image. Long focus Newtonians, i.e. those with high focal ratios (over F/6), can also be good for planets because they have a smaller obstruction. Short focus Newtonians (below F/6) are configured mainly for deep space objects.

If you plan is to observe mainly planets, I’d recommend either a refractor or long-focus Newtonian on a steady equatorial mount with as large an aperture as you can afford. If your primary agenda will be deep sky objects, I’d probably go with a Dobsonian to get as much aperture as possible for the money. A good compromise might be difficult to achieve on a $300 budget.

One final comment: if you can’t get what you want within your budget, then it might be advisable to wait until you can afford to spend more. If you settle for less you could end up being disappointed.


EDIT: I also agree with others that binoculars are a very good way to start out. You can see quite a bit plus learn your way around the sky, which will help when the day comes that you buy a telescope. And even after you get a telescope you'll still have uses for the binoculars, so they're a good investment.

[Ginnie]

What about this?

For $299:
Widely considered to be the BEST CHOICE for a first telescope, the 6" Dobsonian provides enough aperture to support high magnification views of a variety of local and deep space objects.

Ease of operation is the hallmark of the Dobsonian, and that includes easy set up and transport for young and old astronomers alike. This excellent scope comes with a quality 6x30 finder, tension control handles, and two quality eyepieces for 120 and 48 power.

* High Reflectivity, SiO2 Coated
* Paraboloidal Mirror
* Solid Aluminum Tube
* Light Weight
* Easy to Move, Use and Set Up
* Includes quality eyepieces!

KWT DOB6
D =150 mm; F = 1200 mm

[Bob B.]

ginniegatrit said:

What about this?

For $299:
Widely considered to be the BEST CHOICE for a first telescope, the 6" Dobsonian provides enough aperture to support high magnification views of a variety of local and deep space objects.

I would say this telescope, or one like it, is probably the best choice for deep sky objects on a $300 budget. The F/6 optical tube is a good middle ground that should perform reasonably well on both deep sky objects and planets. The biggest drawback of this scope (or any Dobsonian) is that keeping an object centered will require frequent adjustments in altitude and azimuth. This isn't too bad at low magnifications but it can be a nuisance when using high power, such as when observing planets.

EDIT: Is that $299 US or Canadian?

[Ginnie]

Some other info via Wikipedia, on a Dobsonian design:

Advantages

* Compact Size: Basically, a Dobsonian's structure as measured in volume and weight is relatively minimal for any given aperture when compared to other designs. From a cost perspective, a user typically gets more aperture per unit of cost with a Dobsonian. This ratio also ensures that per inch of aperture, a Dob will weigh less and require less space than other types and is thus the most portable design.

* Ease of Use: As an altazimuth mounted telescope that appears very much like an oversize cannon, it is very intuitive to point a Dobsonian. All well constructed Dobsonians have bearing assemblies that move smoothly under finger pressure with minimal backlash. Setting up for hard tube dobs simply involves placing the mount on the ground, and setting the tube on top.

* Excellent Deep Sky Performance: As the original “light bucket” the large aperture and fast focal ratio make these telescopes ideal for deep sky objects. On nights with good seeing, the larger Dobsonians (18 in +) can render most Messier objects in extraordinary detail across the entire field of view of a high-power eyepiece, and can reach fainter objects in excess of 15th magnitude.

* Good to Excellent Planetary Performance: Although originally intended for deep sky objects, a Dob with high-quality well-collimated optics can perform admirably on planetary objects as well. As with all Newtonian telescopes with a central obstruction, the image contrast will be inferior to a refractor. One way for larger Dob owners to get around this is to stop down their telescope with an off-axis-aperture mask to create an unobstructed telescope (in essence, a Herschelian telescope) with theoretical performance comparable to a similar size refractor.

[edit] Limitations

* Non equatorial drive: Because the Dobsonian design is optimized to be a portable, large aperture, inexpensive, deep sky instrument geared towards visual observing, an expensive (and massive) equatorial telescope mount with clock drive was intentionally left out of the design. So the user must nudge the scope every few minutes along both axes to compensate for the rotation of the Earth to keep an object in view. However, since the late 1990s the use of Poncet Platforms as well as computerized stepping motors that can move the telescope along both axes have begun to negate this disadvantage. For visual astronomy these systems work quite well. Newer systems with high-grade stepping motors and a field de-rotator can provide accurate enough tracking for CCD work; however, most serious astrophotographers would likely prefer the inherent stability of an equatorial or fork mount. This limitation also once meant that setting circles could not be used with a Dobsonian, however newer digital setting circles specifically designed for Dobsonian scopes have completely eliminated this constraint.

* Zenithal Hole: Altazimuth mounts are known for being difficult to point at objects near the zenith, though improvements in the azimuth bearing material and design can minimize the problem. Equatorial telescopes have a similar issue when used near the celestial poles.

* Balance Issues: Finally, since the telescope tube is usually fixed in relationship to its altitude bearings, the addition or subtraction of equipment such as cameras, finderscopes or even unusually heavy eyepieces can render the telescope mount unbalanced unless a counterweight or similar modification is added.


It seems like an easy telescope to use, but I don't want to have to take it out in the country ever time to use it. Also I'm worried about the cost if I need an equatorial mount.

[Bob B.]

ginniegatrit said:

… it is very intuitive to point a Dobsonian.

Only if you are use to it.

I have very little experience using a Dobsonian. My telescope is an 8” F/6 equatorial mounted Newtonian reflector, I therefore learned how to navigate the sky by moving the telescope east-west or north-south along lines of declination and right ascension while using a star chart. The one time I used a Dobsonian, every time I nudged it the scope went off in some diagonal direction that I had a hard time anticipating. I was totally messed up. On the other hand, I know people who say how easy it is to use a Dobsonian. It all comes down to what you are accustomed to.

[Ginnie]

Ya know, I'm almost thinking now of getting a good pair of Binoculars and spending a year or so observing the sky and learning where everything is.
It would be very frustrating if I got a telescope and couldn't find things easily because I didn't know the sky.
I'm still undecided.
Also my city has a Royal Astronomical Society of Canada branch. It has meetings once a month and also has sky parties. So maybe hanging out with them a bit would be useful before buying a telescope. If I went to sky parties, I could probably use a variety of telescopes and learn how to use them before actually going out and buying one.

[Ginnie]

bob said:

[

EDIT: Is that $299 US or Canadian?

Is there any difference right now?

Canadian.

[Ginnie]

www.minds.may.ie/~astro2/IFASData/IFASBinocularHandbook.pdf

Found this. Seems like it would be a great guide to using binoculars.

BTW: The only binoculars I have right now is a Simmons 7X25. Not much to use.

[Bob B.]

ginniegatrit said:

Ya know, I'm almost thinking now of getting a good pair of Binoculars and spending a year or so observing the sky and learning where everything is.
It would be very frustrating if I got a telescope and couldn't find things easily because I didn't know the sky.
I'm still undecided.
Also my city has a Royal Astronomical Society of Canada branch. It has meetings once a month and also has sky parties. So maybe hanging out with them a bit would be useful before buying a telescope. If I went to sky parties, I could probably use a variety of telescopes and learn how to use them before actually going out and buying one.

That is a very good strategy if you feel you can wait a year. Go get yourself a star atlas and start learning the constellations and locating bright deep sky objects. The following is a good atlas for use with binoculars:

www.willbell.com/atlas/atlas1.htm

Once you feel confident you can find your way around the sky, maybe you can then get a telescope. The extra year might also allow you to save a little money so you can buy a better telescope. Going to star parties and seeing some of the various telescopes in use can also be very helpful. Talk to different telescope owners to get their opinions and recommendations.

ginniegatrit said:

bob said:

EDIT: Is that $299 US or Canadian?

Is there any difference right now?

I checked the exchange rate after I posted that. I didn’t realize the US and Canadian dollars were as close as they are now.

ginniegatrit said:

BTW: The only binoculars I have right now is a Simmons 7X25. Not much to use.

That’s a little small for astronomy but you can get started with them. A good hand-held size for astronomy is 7x50 or 10x50. I have 7x35 and 10x70. The 7x35 are old ones I’ve had for about forever. The 10x70 are good astronomy binoculars but too big to handhold and work best when mounted on a tripod.

Be sure to consider exit pupil. This is the diameter of the beam of light that exits the eyepiece and is found by dividing the objective lens size by the magnification. For example, 7X50 binoculars have an exit pupil of 50/7 = 7 mm. The fully dilated pupil in a young adult is about 7 mm; therefore the exit pupil of any binocular never exceeds this. However, if your are using the binocular in a place where your eyes will never reach full dilation, then you are wasting some of the aperture. If you have binoculars with a 7 mm exit pupil but your eyes are dilated to only 5 mm, then only about half the light is getting into your eyes – your 7X50 is effectively only 7x35. Furthermore, as a person gets older their pupils don’t dilate as much. I’m currently 49 so my 10x70 is really a mismatch for me; I should consider selling them and getting lighter weight 10x50 or maybe 8x42. Remember that the bigger the binoculars and the higher the power, the more difficult it will be to hold them steady by hand.

[Bob B.]

waspiedwarf said:

You can buy a very inexpensive gizmo that allows a pair of binoculars to be attached to a camera tripod.

Yep, here is an example:

scientificsonline.com/product.asp?pn=3082282&bhcd2=1194990543

Most binoculars have a 1/4" threaded hole in the frame right between the two objective lens (there is usually a little cover piece threaded into it). The adapter threads into this hole and then attaches to a standard camera tripod. I think you can probably pick up a lightweight tripod fairly cheap; maybe you can even find a used one or borrow one from a friend.

The biggest problem with this type of set up is that it is difficult to view objects high in the sky – it is literally a pain in the neck. A tripod works great though when you’re viewing objects low in the sky. For viewing near the zenith it is probably better to recline back in a lawn chair and try to handhold the binoculars as steady as you can. There are special mounts made that hold the binoculars in place as you recline back, but I’m sure they’re more money then you want to spend at this time.

[craiglamson]

ginniegatrit said:

www.minds.may.ie/~astro2/IFASData/IFASBinocularHandbook.pdf

Found this. Seems like it would be a great guide to using binoculars.

BTW: The only binoculars I have right now is a Simmons 7X25. Not much to use.

Have you considered buying a used telescope? I see lots of interesting stuff on ebay from time to time.

Lots of folks buy scopes and then find out you need to stay up deep into the night ot enjoy them :0 ! Away the scopes go.

Good advice on the best scope is the one you actually use.

I have 4 scopes, a little Orion Starblast I can set on a picnic table in the campground,...way small but it get used ALOT!..just for quick evening views...goes with us on every trip.

I have a Meade ext125, my first scope and it is still the second most used because it is very easy to get out, setup and use. Nice views as well. These make the used lists quite often.

Then my wife has a 6 inch Meade refractor LDX55, nice tube, crappy pod and mount...and man is it huge!...But it was theone she wanted...

FInally I have a 8" Meade LX200, Massive, heavy, hard to move and set up, wonderfully solid mount and drive...Il ove it. Only I don't use it as much as even the 99 dollar starblast (got it used at a starparty) because its a major production to set it up and get it running....

The Binos on a tripod mount are a VERY good idea as well!

Might I suggest you attend a local starparty some night and check out a bunch of scopes. Most people at a starparty will gladly tell you about the pros and cons of their scopes and let you view.