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The 8.2-m primary mirror of Yepun, Unit Telescope 4 that ESO’s Very large Telescope, after its recoating in early on March

Here us cover an essential but often overlooked point about telescopes. It may seem strange come cover this, however once you understand this point, you’ll know the trade-offs involved in picking a great telescope for stargazing. The fact is, many beginners think the function of a telescope is come magnify objects, to do them appear bigger. This is not true. What, then, is the objective of a telescope?

The objective of a telescope is to collect light.

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That’s all there is to it. By collecting more light, a telescope makes huge objects like stars, galaxies, and also planets brighter, sharper, and also easier to view visually or come image.

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A schematic the a an easy telescope

To collect light from distant objects, a telescope offers a bent lens or winter (called an objective) and focuses the light to an image at the focal point. The focused image developed by the objective lens the a telescope is magnified by a smaller second lens dubbed an eyepiece.  As visual observers, us look into the eyepiece to check out the bright magnified image native the objective. Yet an eyepiece provided with a little lens or mirror just magnifies a dim and fuzzy image.

So, back magnification is useful, it has actually no effect in helping you see information in a telescope. The detail and also brightness of photo all comes under to the lot of light gathered by the target lens or mirror. And that relies on that is diameter that the objective, likewise called the aperture. Choose a huge bucket collects much more raindrops 보다 a little bucket, a huge objective collects much more light than a smaller one.

Let’s use an example. Stop look in ~ Jupiter through two telescopes, one with a key lens the 2″ diameter and one through a key lens that 4″ diameter, and pick eyepieces for each telescope to give a magnification the 100 time (or 100x). So each picture will appear to be the very same size.

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An approximation of the image of Jupiter in a 2″ (left) and 4″ telescope.

In the telescope with a 2” aperture, Jupiter’s biggest cloud belts will certainly be clearly observable but a tiny dim and fuzzy. However in the 4″ telescope, the exact same cloud belts will certainly seem to take it on much more structure and color, and also smaller cloud belts are now visible that might not be watched in the smaller sized instrument. The bigger telescope’s benefit in collecting light makes it possible to see an ext detail 보다 is possible through the smaller telescope at the same magnification. Watch the photos above.

So a telescope that collects more light offers a better view. That method choosing a telescope need to be simple, right? Simply choose the telescope with the greatest objective lens or winter that you can afford.

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Well yes, but there are trade-offs. Telescopes with bigger aperture are more expensive, heavier, and in some cases, more difficult to usage than smaller telescopes. They also give a narrower check out of the night sky than smaller sized telescopes. For this reason you need to take every one of this right into consideration. Just mental for currently that the purpose of a telescope is to collection light, and an ext light renders for a better image and a more enjoyable observing experience.