# What do the numbers mean on a telescope?

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A telescope’s focal length divided by its aperture is called its focal ratio, which is conventionally written as “f/” followed by a number. For instance, a 6-inch f/8 telescope has an aperture of 6 inches and a focal ratio of f/8. That means that its focal length is 6×8 = 48 inches, or roughly 1,200 mm.

## What is a good magnification for a telescope?

For most purposes, a telescope’s maximum useful magnification is 50 times its aperture in inches (or twice its aperture in millimeters) . So you’d need a 12-inch-wide scope to get a decent image at 600×. And even then, you’d need to wait for a night when the observing conditions are perfect.

## How can you tell how strong a telescope is?

To figure out the magnification, divide the focal length of the telescope by the focal length of the eyepiece: If you have a 25-millimeter eyepiece and a refractor of 900 mm, the magnification is 36 power, written as 36x (or, 900 / 25 = 36).

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## What does a 14 inch telescope mean?

14 Inch Telescopes offer exceptional resolution for their size. They can resolve double stars at . 33 arcseconds and can be magnified up to 712 times the human eye. 14″ Optical tubes also make exceptional light gatherers by allowing an observer to see 16.5 magnitude stars!

## What can you see with a 400mm telescope?

Answer: One of the farthest away objects you should be able to easily see with this telescope is the Andromeda Galaxy, which is a mere 780 kiloparsecs from Earth. Because this telescope has a shorter focal length (400mm) it is good for low power, wide field views of the sky.

## How good is a 70mm telescope?

With a 70mm telescope, you will easily be able to see every planet in the Solar System. You will also be able to take a great look at the Moon and clearly distinguish most of its recognizable features and craters. Mars will look great. … The magnitude limit of a 70mm telescope is about 11.9.

## How powerful does a telescope have to be to see the rings of Saturn?

The rings of Saturn should be visible in even the smallest telescope at 25x [magnified by 25 times]. A good 3-inch scope at 50x [magnified by 50 times] can show them as a separate structure detached on all sides from the ball of the planet.

## What can you see with a 500mm telescope?

A 500mm telescope will yield a lunar image that’s about 5mm across in a DSLR camera with a full-frame, 35mm-format sensor; a 1,500mm telescope will produce a 14mm image, and a 2,000mm telescope results in an 18mm image.

## What can you see with a 100mm telescope?

What Can You Expect From 100mm Telescopes? (With Photos)

• The maximum magnitude of a 100mm telescope is 13.6. For reference, the Moon has a magnitude of -12.74 and Mars has a magnitude of -2.6. …
• The Moon. The Moon looks amazing in these telescopes. …
• Mars. …
• Venus. …
• Jupiter. …
• Saturn and Neptune. …
• Pluto and Dwarf Planets. …
• Mercury.

## What can I see with a 40x telescope?

At 40x you can use the scope for several astro viewing aspects: Clusters, Open and Globular, double stars, some nebula – M42 being the obvious. Depending on how dark your skies are some planetary nebula. And as ever in this hobby there is the moon.

## Is a 10 inch telescope good?

Choosing a 10″ inch aperture scope is a great size where you can find very capable instruments and not needing to spend a fortune. It’s also a great capacity and size factor. These telescopes will not be small or compact yet they have a comfortable size to be able to travel with.

## Is an 8 inch telescope good?

An 8-inch telescope (it doesn’t matter what type) will move you into a new dimension of viewing. The objects you see with an 8-inch scope will reveal more detail. Keep in mind, however, that if you stay interested in observing, you’ll crave even larger scopes.

## What can you see with a 20 inch Dobsonian telescope?

The massive mirror in this Dob allows much more light to be reflected into the eyepiece than a typical telescope. If you can handle all of the extra weight and transportation requirements, a giant 20″ Inch Dobsonian will offer you views of Nebulae, Galaxies and Star Clusters like you have never seen before.

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## What can you see with a 90mm telescope?

A 90mm telescope will provide you with a clear view of the Saturn along with its rings, Uranus, Neptune, and Jupiter with its Great Red Spot. You can also expect to see stars with 12 stellar magnitude with a 90mm telescope.

## What does 70mm telescope mean?

A 70mm telescope (2.8” aperture size) will provide you with a clear view of the Moon and its craters. You can also check out some of the bigger planets in the solar system. Though don’t expect to see every detail of the planets. Things You Can See With a 70mm (2.8” Aperture) Telescope. Objects With In the Solar System.

## What can you see with a 12 inch Dobsonian telescope?

What Can You See with Dobsonian Telescopes?

• Near Space Objects – The Moon, Planets, The Sun. …
• Deep Space Objects (DSOs) – Galaxies, Nebulae, Clusters. …
• Easy setup and use. …
• Portable by design. …
• Reflecting telescope. …