# What Size and Material Should I Use for My Refractor Telescope Tube?

• Stargazing
• purina
In summary, a focal point in a telescope is where all incoming light rays converge to form an image. It is determined by the curvature and positioning of the telescope's mirrors or lenses. The focal point is different from the focal length, which is the distance from the center of the lens or mirror to the focal point. The focal point can be adjusted by changing the distance between optical components and it affects the magnification of a telescope. A shorter focal length results in a larger magnification while a longer focal length results in a smaller magnification.
purina
so i am building a refractor telescope and i don't know what size to make the tube and what material to use for it?

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You need to start by selecting the lens. It determines the size of the tube.

## 1. What is a focal point in a telescope?

A focal point in a telescope is the point where all incoming light rays converge after being reflected or refracted by the telescope's optical system. It is the point where the image of the observed object is formed.

## 2. How is the focal point determined in a telescope?

The focal point in a telescope is determined by the curvature and positioning of the telescope's mirrors or lenses. The shape and distance of these components determine the convergence of light rays at a specific point, known as the focal point.

## 3. What is the difference between the focal point and the focal length of a telescope?

The focal point is the specific point where light rays converge after passing through a telescope's optical system, while the focal length is the distance between the center of the lens or mirror and the focal point. In other words, the focal length is the distance from the lens or mirror to the focal point.

## 4. Can the focal point of a telescope be adjusted?

Yes, the focal point of a telescope can be adjusted by changing the distance between the optical components, such as the lenses or mirrors. This allows for the image to be focused and adjusted for different viewing conditions.

## 5. How does the focal point affect the magnification of a telescope?

The focal point of a telescope plays a crucial role in determining its magnification. A shorter focal length results in a larger magnification, while a longer focal length leads to a smaller magnification. This is because a shorter focal length will bring the image closer to the eyepiece, making it appear larger.

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