Looking at the sky at night is enough to observe the stars and planets, but to capture the wonders of the universe, you need a telescope.

In the past, telescopes were tools reserved for astronomers and research scientists who were tasked with uncovering the mysteries of the universe. Today, with mass production and the advancement of technology, telescopes have become affordable tools for anyone with curiosity and patience.

If you're new to the world of telescopes and astrophotography, this article will help you understand the basics so you can take your first steps into this fascinating hobby.

What are telescopes and what are they for?

Let's start with the basics. A telescope is an optical instrument designed to observe distant objects by enlarging their apparent size and capturing more light than our eyes can perceive.

When our pupil expands to the maximum, our eyes can only pick up a little light, but a telescope can pick up a lot more.

The primary purpose of a telescope is to collect and focus as much light as possible from the stars to give us a detailed image of celestial bodies such as planets, stars, nebulae, and galaxies.

Broadly speaking, a telescope works like a funnel, where the large nozzle is the primary lens (the one pointing to the sky), and the small nozzle is the secondary mirror (through which we observe what the primary lens captures). Like a funnel, the larger the nozzle (primary lens), the more light it can capture.

This means that the power of a telescope does not depend on how long the main tube is but on how wide the primary lens is since this is the one responsible for collecting the light from the star. This is why the most essential part of a telescope is the lens or primary mirror. This also defines the type of telescope.

Types of Commercial Telescopes and How They Work

Now that you know how a telescope works, let's move on to the next stage: How many types of telescopes are there?

The type of telescope depends on the optical system you use. There are three main types of systems: reflectors, refractors, and catadioptric.

These telescopes are ideal for hobbyists and professionals as they have features that suit different needs.

Refracting telescope or Galilean

The refractor telescope is sometimes called the Galilean telescope in honor of the father of astronomy, Galileo Galilei, who used this telescope to observe the stars and discover Jupiter's system of moons.
This type of telescope uses lenses to focus light. The primary lens, called the objective, is located at the opposite end of the eyepiece. This type of telescope is known for:

• Advantages: Clear and sharp images, especially for observing planets and the Moon. They are robust and require little maintenance.
• Disadvantages: They can be expensive at large apertures and prone to chromatic aberrations (colored edges in images).

Refractor telescopes are usually best for beginners as they are cheaper, easier to use, and lighter to carry around. However, they are not as powerful as the ones below.

Reflecting or Newtonian telescope

The reflecting telescope is also called Newtonian in honor of Sir Issac Newton, who used it to discover the visible light spectrum.
Unlike a refracting telescope, which uses magnifying lenses, a reflecting telescope uses mirrors to collect and focus light. Thus, it is called a "reflector" since it reflects light instead of refracting it.
The most common design is Newton's, which uses a parabolic primary mirror and a secondary mirror tilted at 45°.

• Advantages: It has a great capacity to capture light, ideal for faint objects such as nebulae and galaxies. It has a very favorable cost-opening ratio.
• Cons: Requires regular adjustments (collimation) and can be bulkier.

This telescope is usually recommended for a more experienced audience who have already used telescopes, as its operation and maintenance are more advanced. It is usually more expensive than refractors, bulkier, and much heavier, so it requires special equipment such as custom boxes to transport it. It is not recommended for children.

Catadioptric telescope

It combines the two previous systems into one; that is, it has lenses and mirrors, maximizing the advantages of both systems. The two most common types are Schmidt-Cassegrain and Maksutov-Cassegrain.

• Pros: Compact, versatile, and easy to carry. Suitable for both visual observation and astrophotography.
• Cons: More expensive and with some light loss due to multiple optical elements.

These are complex telescopes because their technology combines lenses and mirrors. They are more expensive than refractors and reflectors, and computerized tracking mounts and custom-made carrying cases usually accompany them. The slightest blow or impact can decalibrate them, and their maintenance is complex and requires special tools.
Its operation requires the user to have advanced astronomical and optical observation knowledge, so it is not recommended for beginners or children.

Research telescopes

Finally, among the types of telescopes are those of large observatories (such as the Gran Telescopio de Canarias or the Anglo-Australian telescope of the Siding Spring Observatory) and space telescopes (such as Hubble or James Webb).
These types of telescopes are designed for advanced scientific research. They are used for the study of the universe and the observation of extraordinary events such as galaxies, supernovae, pulsars, neutron stars, and much more.
Although they are fascinating, the reader should know that these types of telescopes are only available to scientists and researchers from all over the world, such as astronomers and astrophysicists who are dedicated to the professional study of the universe. However, that does not mean they cannot visit them. At least the ones on Earth.
Fortunately, most of the world's observatories are funded by research centers and universities, which often organize guided tours so that people interested in astronomy can go and see them in person.

Mounts: Types, Differences, and Similarities

Now that we have discussed the types of telescopes, it is time to discuss the mount. This is the support that holds the telescope and moves it to point toward different parts of the sky. Although it seems simple, you should know that there are several types of mounts, each with its particularities.

Altazimuth Mount

It moves on two axes: up-down (altitude) and side-by-side (azimuth). It is easy to use and suitable for beginners.

• Pros: Simplicity and low cost.
• Cons: It does not follow the movement of the stars, which makes it difficult to take long exposures in astrophotography.

Equatorial Mount

It is designed to align with the Earth's axis of rotation, making it easy to track celestial objects with a single adjustment.

• Pros: Ideal for astrophotography and extended observation.
• Disadvantages: More complex to set up and more expensive.

Dobson Mount

A simple and inexpensive variant of altazimuth. It is usually used with large-aperture reflector telescopes.

• Pros: Accessible and perfect for visual observation of deep-sky objects.
• Cons: Not ideal for beginners or children.

Computerized mounts (GoTo)

These mounts include a motorized system and a database of celestial objects, making it easier to find and track stars automatically.

• Pros: Convenience and accuracy.
• Cons: Expensive and require electricity to operate.

As you can see, mounts are more than supports; they are a fundamental part of your telescope's proper functioning.

Eyepieces: What they are and which ones to choose

Another fundamental part of telescopes is eyepieces. These optical pieces are placed at the end of the telescope where the eye goes, allowing the image formed by the primary lens or mirror to be observed. They are interchangeable and determine the magnification and quality of the eyesight.

Types of eyepieces

• Plössl: Versatile and affordable, they offer good optical quality.
• Orthoscopic: Excellent for planetary observation, thanks to their sharpness.
• Large field: Ideal for observing large sky regions, such as star clusters.
• Zoom: Adjustable to vary the focal length and magnification.

The choice of an eyepiece depends on the type of object you want to observe and the characteristics of your telescope.

Pointers: What they are and what they are for

Among the lesser-known accessories, but no less important, we have the pointers or seekers. As their name says, they are small telescopes or sight mounted on the main tube. Their function is to help locate celestial objects before observing them with the telescope.

Types of pointers

• Optical: Small telescopes with reticles.
• Red dot: They project a luminous point in the sky, facilitating alignment.
• Green lasers: They indicate the desired object with a visible light beam.

Other useful accessories

Filters: They can be solar, lunar, and deep-sky filters, improve visibility, and highlight specific details.
Cameras: Astronomical cameras, such as CCDs, are critical for capturing detailed images in astrophotography.
Adapters: Allow DSLR or mobile phone cameras to be attached to the telescope.
Collimators: Essential tools for aligning the mirrors of reflecting telescopes.

The importance of astrophotography

Astrophotography is not only a visual art but also a scientific tool. Many amateurs have made significant contributions to astronomy through observations and discoveries.

An example of this could be Anthony Wesley, an Australian amateur astronomer who discovered the impact of an asteroid on Jupiter in 2009.

Perhaps the best-known example is William Herschel, who, despite having trained as a musician, became interested in astronomy as a hobby. He built his own telescopes and learned in a self-taught way. His most famous contribution was the discovery of the planet Uranus in 1781, the first planet discovered in the modern era, significantly expanding the known scope of the Solar System.
In addition, he cataloged more than 2,500 nebulae and star clusters and established critical concepts about the structure of our galaxy that are vital to the study of the universe today.

These examples demonstrate that passion and effort can open doors in the knowledge of the universe, even without professional training in astronomy.
Entering the world of telescopes and astrophotography is to start an exciting journey into the cosmos. Whether observing the craters of the Moon or capturing the majesty of a distant galaxy, every step will be an adventure filled with learning and wonder. The universe is waiting for you!