What determines a good telescope?

Question

This telescope is for my 10 yr. old. She would want to observe stars, planets, etc. We live in a small town with little pollution.

Answer 1

In general, the optics have to be well figured and polished, and the mechanical parts must be sturdy and move smoothly.

An experienced observer can tell good optics by examining the image of a star at high power. Lacking that, you need to rely on the experience of others, or manufacturers reputation. Buying from a reputable telescope store will generally protect you from the worst buying real junk. There are some online astronomy forums where you can get advice, also.

The mount is often overlooked, but without a sturdy support with smooth motions you'll have a very hard time observing anything.

All other things being equal, aperture (the diameter of the main lens or mirror) is the most important thing. Larger aperture will show objects both brighter and sharper. Avoid telescopes being advertised on the basis of magnification over 300x.

Added:
The Orion Starblast is a good telescope for a child. A certain amount of adult assistance will make it more fun for all involved. Another good kid's scope is the Astroscan. (google for it) This is a less capable scope than the Starblast, but simpler, sturdier, and easy to use.
http://www.telescope.com/shopping/product/detailmain.jsp?itemID=4644&itemType=PRODUCT&RS=1&keyword=starblast

Answer 2

A good telescope has diffration limited optics, enough aperture (the diameter of the primary mirror or lens) to see a decent number of objects, and a good, sturdy mount.

The smallest telescope I recommend buying is one that has at least 4.5" of aperture. This just allows you to see the tip of the iceberg though. If You can manage it, you should really aim for something that's 6" or 8" in aperture, and preferably 8" in aperture.

In this case the telescope will either be a newtonian or dobsonian reflector, or a catadioptric such as a Schmidt Cassegrain. The Dobsonians are the cheapest but are on simple mounts which she won't be able to do astrophotography with in the future. The Schmidt Cassegrain would be the more expensive one but they often come on computerized drives which have tracking for astrophotography.

To get her a decent telescope you should expect to spend around $400. For this reason, I highly recommend buying her a used one. Most used telescopes have been well cared for and if she loses interest you will be able to sell it for at least as much as you bought it....which will be 1/3 to 1/2 the price you'd buy it new.

Regardless of the type of telescope you buy her, she will need at least two good eyepieces and a high quality 2x barlow, which is a special attachment that increases the magnification of the eyepiece while keeping the field of view the same. You can get these used as well. The two eyepieces should be between 25mm-32mm in focal length and then 9-12.5mm in focal length. The barlow should be from a reputable company such as Orion, TeleVue, Celestron, Meade, or a similar company and be fully coated.

The above companies also make decent telescopes (but watch out for the department store lines). Contact your local astornomical society and you will most likely find someone who is willing to help you pick out a telescope. You can find used ones on http://www.astromart.com in the classifieds.

Answer 3

Well, technically, there are two type of telescopes. Reflecting and Refracting.

For Reflecting telescopes, you need to look at the diameter of the concave mirror.

For Refracting telescopes, you must look at the diameter of the objective lens.

I really don't know if a ten year old can handle a complex reflecting telescope. But who knows?

Answer 4

depends on what type of telescope u want to use. good telescope usually can observe stars or any object that outside there around 3 billion light away from earth. usually telescope which can observe far object has high power. the basic to build a telescope is by using two types of lens which is objective lens and eyepiece lens. objective lens are placed in font of eyepiece of lens and have long focul lenght. function of eyepiece of lens is to capture any image from great distance to produce real, inverted and diminished image. then eyepiece lens which is put behind the objective lens has short focul lenght to change the first image captured by the objective lens into virtual, inverted and magnified image
i know it is hard 4 u to understand but try to refer diagram it will help u more on how to understand the principe of telescope

Answer 5

well what do you wanna observe?
where do you want to observe - in a town you can have the best telescope ever but light pollution destroys every good night!
how good is the seeing at your place?
do you want to navigate the telescope via computer?
'till which magnitude do you wanna observe? you have to give me some more information before I can recommend you something.... how much should it cost?

I could help you so if you give me more details .... simply email me

Answer 6

gentle amassing capacity right away proportional to the outdoors area of the lens, which interior the case of a circle or disk varies because the sq. of the diameter. So an objective lens two times the diameter of yet another could have 4 cases the gentle amassing capacity.

Answer 7

Aperature. You should consult an astronomer before buying one, try to get the most for your dollar!

Answer 8

price