As far as light gathering properties are concerned, if you plan on using your binoculars in any kind of low light situation whether indoors, or at times of day when there is low available light outdoors, then you need to have a large objective lens, usually 30 or above, to make as much use of available light as possible.

Finally, consider weight of binoculars before buying them. If weight will be a consideration for activities such as hiking, then perhaps plastic lenses will be best that are specially coated to produce a high quality, sharp image. These can be more costly than glass lenses, but they are considerably lighter. Glass lenses usually make for much better optics and clearer images at a lower overall cost, but they can also be more fragile.

Generally speaking, more expensive pairs of binoculars have more atention paid to fit and finish and will stand up to more vigorous use, but if you only plan to occasionally use your binoculars, then a less expensive pair will no doubt work fine. Also, remember that after purchase you should be sure to protect your investment with a suitable binoculars case.

It's also important to know that there are three different kinds of telescopes, reflector, refractor and catadioptric.

The refractor is kind of telescope that most people think of when they think of telescopes. It essentially has a large lens on end of a barrel that focuses an image on an eyepiece at back of barrel. It's actually a very simple design, but it can also be more costly and bulky than other styles of telescopes available. It's good for viewing night sky and long range here on earth, but again, it gets very expensive to produce when you want to see deep space objects.

The next kind of telescope is reflector, and it uses mirrors to gather light and focus it on a small eyepiece that is usually located on side of barrel. Mirrors are much less expensive to produce than lenses used in refractors, so reflector telescope is usually much less expensive as well. It is not suitable for terrestrial viewing here on earth though and it does lose a little light due to use opf mirrors in it's design.

The final style of telescope is catadiaoptric which is really a blend of both refractors and reflectors, essentially taking best of both designs with few of drawbacks. It is a good all around selection for telescope usage as it is a good choice for both terrestrial and astronomical viewing. They may not be what you expect a telescope to look like but their design is very modern and durable.

Choosing any of these types and styles of telescopes will work depending on what you plan to use your telescope to do, and your budget. The important choice is to embark on a discovery of parts of universe that you have never seen before.