Is a 50x/100x lense telescope worth buying?

Question

will we be able to see anything ? or should be go for a higher strength lense?

price is: $ 19.99

Answer 1

You probably mean a 100mm x 50mm. This telescope has a 100mm focal length and 50mm in diameter lens, and since it has a lens, it's a refractor.

Without anymore information, my guess is that this is a cheesy cheapo telescope and is not worth buying. The only refractors I really recommend are at the very very least, achromatic, and idealy, apochromatic, and I don't recommend anything which has a lens less than 80mm in diameter. A quality 80mm apochromatic refractor starts at about $400-$500 and that usually only includes the tube with the optics.

It is not the "strength" of the telescope you should be concerned about. Aperture is the most important part of a telescope. Aperture is the diameter of the telescope's lens in the case of refractors, and primary mirror in the case of reflectors. Bascially, most things in the sky are fairly dim to human eyes because our eyes can only collect as much light as our pupils will let in. This really isn't a lot of light because unlike most mammals, we are day dwelling creatures, where there is an abundance of light. The lens or mirror in a telescope collects light over a much larger area...the area of the lens or mirror, which is often many inches in diameter, not just 7mm or so. A telescope with a mirror or lens that is 4.5" in diameter will collect roughly 267 times more light than the naked eye, making many dim objects bright enough for you to see.

The larger the telescope is in diameter, in general, the longer the telescope's focal length must be. This is what will help you if you want to use high magnification. The magnification ability of a telescope is determined by an equation.

Magnification = (telescope focal length)/(eyepiece focal length)

If you had a 25mm eyepiece and used it in an telescope that was 1000mm in focal length and 2000mm in focal length, the objects would be twice as big in the 2000mm focal length telescope.

If you were to use a 12.5mm eyepiece (higher power) in the 1000mm focal length telescope, so it'd give you the same magnification as the 25mm eyepiece in the 2000mm focal lenth telescope, the telescope with the 2000mm focal length will give you a clearer view because the resolving ability of the telescope increases with aperture and the 2000mm focal length telescope most likely has more aperture.

So to sum things up, with telescopes, the bigger the better.

Answer 2

If it is used you might take a chance. Be aware that cheap telescopes yield bad images, so if it is a new one, beware!

To get 100x magnification (which is more than enough to see the moon craters, rings of saturn, cloud bands on jupiter, and many nebulas) you need an objective lens (big lens at the other end of the scope, away from the part you look through (the ocular) or mirror at least 2.5 inches across. For that matter 50x is enough to see most of the things I mentioned above. The best way to tell is to try it out on a nice, clear night. Look at the moon, try to find a planet, or a bright nebula (or the Andromeda Galaxy) and see what you can see. My guess is it will be a disappointment. (Be aware that the photos you usually see of nebulas are time exposures..even with a kick-butt telescope you won't see them like that...you'll see a hazy patch, with more detail in the larger telescopes).

Answer 3

Never buy an astronomical telescope on the basis of its magnification - it's the aperture that matters. 50-100x is fine for lots of things, but for $20 I'd be amazed if this is even usable. If you haven't got money to burn, get binoculars - they're a much better introduction to astronomy than a bad telescope.

Answer 4

I wouldn't pay more then $50-99 for something like that.