tips

pkumohideeile

hey im looking to buy a telescope probably second hand, have you got any suggestions on what i should be looking for when searching ads because i have no experience, im a total beginner.
any tips appreciated, thanks

Flukey

If you have no real experience with astronomy and are a total beginner, forget about a telescope for now and go with the binoculars.T he best thing to do is get yourself a good pair of binoculars and get used to the night sky with them. A set of 10 x 50 are best. There are many advantages, like being able to scan the sky quickly and or follow things as they move. Get a good star atlas. There are plenty available in the good bookshops. Build up your knowledge and interest that way first. Once you know a bit more and get more interested, then perhaps consider getting a telescope. Keep an eye in here and other similar sites for information on what to look out for. There is a partial eclipse of the moon tonight for example.

If you do decide to get a telescope, do a search for various astronomy and telescope sites. There are plenty about. They'll give you plenty of tips on what to look for and what the terminology means. You'll also get tips in any good star atlas you buy. Your budget will of course be an important factor when it comes to buying. The really cheap ones, that you often see in camera shops, are generally not much use for the pursuit of astronomy, so be careful what you buy.

pkumohideeile

thanks for that flukey ill give that a shot cheers

slade_x

The following may seem a little all over the place as i am just copying and pasting what i typed in another forum just for ease

Original Location -thread where i posted originally

Firstly do you live in a well lit area where street lights can pollute your view of the very vast blanket of stars that you should see above you? It is also important to know your price bracket.

http://www.telescopes.com have an excellent range of telescopes for you to look at with pricing. It's well worth a look even if you dont purchase from them. it will give you a good idea what to expect.

Now which one you pick as your first telescope is very important, if you get the wrong one I can almost guarantee you will lose interest right after you go looking for anything other than the moon, since you are a beginner the mount you use is very important. The best choice for you is either a “go-to drive” enabled mount or an Equatorial which go-to’s basically are anyway. Stability in a mount is absolutely essential. You don't want it shaking all over the place at every touch.

As a simple lesson the most basic mount is the Alt-azimuth with two basic axes of rotation, vertical and horizontal, exactly like you would see with a camera mountable tripod. Because of its simple range of motion you cannot properly track stars as relative to an observer on earth celestial objects follow an arc like motion across the sky. So in your case if you were observing Saturn it will only remain in the field of view after first finding it for a matter of seconds, you will have to constantly re-adjust to keep in view (track) which can be frustrating with alt-azimuth. However this can be achieved with relative ease with go-to drives automated tracking (or, even manual tracking is made simple with autostars control) or equatorial mounts;

With an equatorial mount you get two perpendicular axes of rotation (identified as Right Ascension and Declination which is a celestial coordinate system) only instead of the simple up/down, left/right range, it is tilted at the same angle in relation to the earth’s axis. And thus will easily allow you to follow a smooth arc motion across the sky. Perfect for tracking even the fastest stars across the sky.

Another important aspect is the type of telescope itself, there are 2 main types; Refractor (a traditional looking telescope) and a Reflector (Newtonian Reflector) to keep it simple each has their strong points:

Refractors have very good resolution which is perfect for planetary details, but they get very expensive for the bigger ones as it’s harder to make larger objective lenses for them, so very costly per unit of aperture, and sadly because of this limited aperture its less efficient for observing faint objects such as galaxies and nebulae than a reflector

Now Reflectors are Rich field telescopes, which offer wider fields of view because of their lower focal ratios, the focal ratio is the focal length of the telescope divided by its aperture (diameter of the objective lens) The reflector telescopes dont have limited apertures like refractors and thus provides brighter observations of deep sky objects like nebulae, galaxies, star clusters (a well known and beautiful cluster is Pleiades which you can easily find under the Andromeda galaxy) and even comets. Suffice to say they are inexpensive in relation to cost per unit of aperture, but sadly all reflectors are subject to some light loss but its not much of a concern here, you get a bigger telescope with more light gathering ability for your money if you choose a reflector over a refractor for the simple fact that reflectors objective lenses can be made bigger and coincidently are a lot cheaper.

Another 2 types of telescopes are Dobsonian and Catadioptric;

Dobsonian telescopes are more notably very large versions of Newtonian reflectors .They are inexpensive to build and can have very large apertures, due to this they are excellent at observing deep sky objects like I mentioned above but are also adequate at observing planets, and but by no means are they portable. Dobsonians are well known for being massive telescopes and the beauty of it is, you can get a good 8 Inch dobsonian for about $300, although you’d better have the space for one

Catadioptric telescopes are basically hybrid telescopes, which are a mix of reflectors and refractors. These type are more associated to the go-to drive enables telescopes and are really expensive

Now as this took me a while to write, I’m sure there’s already a ton of suggestions like don’t buy from a local camera shop etc, and the bigger the better which is not true at all. I can’t stress enough that the quality of the optics and overall spec of the telescope are far more important, having that said you will not go wrong with brands like Meade, Celestron, Bushnel, Zhummel. I absolutely love Meade Telescopes

As this will be your first telescope buying additional eyepieces won’t be necessary for a while as you will get everything even an amateur would need.
However some accessories you may be interested would be a Solar filter (excellent investment and DONT buy a cheap one, buy one made specifically for your telescope, preferrably a screw on) and also additional lunar and planetary colour filters sets if you'd like, all of which you can find and purchase on the site I provided above.

To give you a little insight here is a low magnification pic of Saturn attained with a mounted webcam (Objective Lens diameter of 70 mm)



EDIT: To correct the statement in the post above: - from another user

"The larger the aperture, the more light gathered and thus, a brighter and more detailed image."

A larger aperture ensures more light gathering ability thats it. it is up to the telescope itself to be able to focus that light onto a point on your eyepiece this is where the focal length and ratio comes into play. quality of optics is also a bonus and in the case of refractors can feature apochromatic lenses which eliminates chromatic abberation, which you can see in the above image (the red and blue) this is the result of using an achromatic refractor

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Extra post i made Original location


Actually there was one thing i neglected to mention now after reading Inepts post, even with that particular telescope you will be able to view some of Saturns moons as well as saturn itself (wide field at low mag i mean) which is a pretty satisfying site in itself, oh and also 2 or 3 of jupiters moons maybe

Other helpfull information i never included in my other post would be how to determine what a telescopes theoretical max magnification would be and determining how much power each eyepice will give

To start the rule of thumb is that the theoretical maximum *usable* amount of magnification is twice the aperture in mm, so a good 70mm will be 140x

To determine eyepiece magnification which comes in really handy when your interested in buying additional eyepieces to suit your telescope. all you do is divide the telescopes focal length by the eyepieces focal length

for example take the linked telescope, i know they dont state the focal lenght of it on the site but i have determined it to be about 1000mm which is pretty good but bordering on excessive for a 70mm.
It does say the eyepieces included; a 9.7mm and a 26mm.

1000/9.7 = 103.092 => 103x
1000/26 = 38.46 => 38x

Because of all the factors involved with oberving on this planet 103x with that telescope i would say would almost just be its focusable practical limit ( maybe 110x) however if you could commendeer a space shuttle and a suit then you may easily get about 140x of focusable magnification with that scope.

Although it is important to mention that if you do intime upgrade to a bigger telescopes you should know that any eyepieces you do have or buy in the future will provide much more focusable magnification if the telescope has the light gathering ability to complement its overall focal ratio.

for example take a 10 Inch Dodsonian with a typical focal ratio of 1350mm with the current eyepieces
10 inches would rougly be 250mm so that in theory is 500 times of usable magnification

1350/9.7 = 139.175 => 139x
1350/26 = 51.92 => 52x

As you can see they are nothing fantastic but they would be perfect for wide field viewing

Good luck!


Sorry if it may seem all over the place:(