Simple Telescopes

A simple telescope, also known as a refractor telescope, mainly consists of two lenses: the objective lens and the eyepiece lens.
The Objective Lens is the largest lens in the telescope, situated at the front. It gathers light and focuses it to a point inside the telescope, forming an image.
The Eyepiece Lens is smaller and situated at the rear of the telescope. It magnifies the image formed by the objective lens, allowing the observer to view it in detail.

The lenses in a simple telescope work through the principle of refraction - the bending of light as it passes from one medium to another.
The objective lens refracts (bends) the light it collects to create an image at its focal point. This image is real, inverted (upside down), and smaller than the actual object.

Magnification is a measure of how much larger an object appears through the telescope compared to the naked eye.
It’s calculated by dividing the focal length of the objective lens by the focal length of the eyepiece lens (Magnification = objective focal length / eyepiece focal length).
Larger magnification doesn’t always mean better. Too high magnification may result in blurry images due to increased atmospheric disturbances.

Advantages of simple telescopes include their durability, ease of use, and they don’t require collimation (alignment of lenses and mirrors). They also give crisp and high contrast images.
Disadvantages include chromatic aberration (colour distortion), less magnification compared to reflector telescopes of the same size, and they are generally bulkier and heavier.

When choosing a telescope, consider the aperture - the diameter of the telescope’s main optic. A larger aperture collects more light, which enables observation of fainter objects.
The focal length is the distance over which the lens or mirror brings light to focus. A longer focal length will provide higher magnification but a smaller field of view.
The telescope should be stable and easy to use. An unstable or complex telescope may deter beginners from pursuing this rewarding hobby.

Telescopes should be kept clean and dry, and covered when not in use to prevent dust accumulation.
Avoid touching the lenses or mirrors with fingers, and clean them only when necessary using proper cleaning kits to avoid scratches and damages.