How to use the telescope: 5 useful tips

How to use the telescope is one of the fundamental aspects for those who want to approach the amateur observation of the cosmos, or for those who are already passionate about the observation of celestial bodies. Have you also decided to buy a telescope, or do you want advice on how to organize your observing evening? We provide you with a general overview on how to use the telescope, starting from the main models and then moving on to the pre-observation and observation phase.

Types of telescopes: reflectors, refractors, catadioptrists

Preliminary to a purchase of a telescope is the knowledge of the various types of telescopes. There are three main types:

Reflectors – they only use mirrors.

ADVANTAGES: ease of use; fast acclimatization, high image quality.

DISADVANTAGES: more frequent collimations; lack of pursuit; unsuitable for astrophotography.

Refractors – use only lenses.

ADVANTAGES: ideal for astrophotography; ease of use; high image quality.

DISADVANTAGES: higher price compared to the opening dimensions; small opening; false colors.

Catadioptrists – use mirrors and lenses. For this reason they are a “hybrid” form between reflectors and refractors.

Types of mounts: equatorial and altazimuth

Another aspect to consider when buying a telescope is the mount that can be of two types:

Equatorial: type of mount that allows you to follow a celestial body in the sky.

Altazimuth: gives the possibility to follow parallel movements (Azimuth) and perpendicular to the horizon (height).

Before observation …

1) Acclimatize

After having planned the observing evening in advance of the beginning of the astronomical night, to use the telescope in the best way, you must first acclimatize the instrument. When we transport a telescope from one place to another, the optics need some time to adapt to the outside temperature.

2) Collimate

Collimation is the preliminary step to get the best possible image quality and to use the telescope in the best way. It means aligning the mirrors and the lenses of the instrument along a common optical axis. To correctly align a Newtonian reflector, follow these steps:

• use the telescope to aim a bright star with a low magnification eyepiece and blur the image.
• The dark shadow of the secondary mirror should be in the center of the luminous circle obtained with the blur.
• If this is not the case, proceed to center the dark shadow by acting on the primary mirror screws.
• It is then necessary to gradually bring the dark shadow back to the center of the blurred light circle, increasing the magnifications.

During the observation: useful ideas

3) Star hopping

The “star-hopping” method.  Is the method that allows you to identify stars, celestial objects starting from a brighter star and moving with the seeker following a trace of weaker stars, until you reach the desired object.

4) How to use the telescope in the city (or from the terrace): what can be seen

Given the light of inhabited places, observing the objects of the deep sky from the courtyard or home is not always possible. The most easily identifiable objects with a medium-sized telescope are: the Moon, the planets and some double stars, planetary and emission nebulae, globular clusters. We must know well what to look for and in this case we can orient ourselves with the Moon, thus printing celestial papers to identify the position of stars and planets.

5) Observe the objects of the deep sky

• observe the objects when they are near or near the zenith, then high in the sky;
• adapt completely to the darkness;
• observe from a dark site, devoid of artificial lights;
• keep both eyes open during telescope observation;
• use different magnifications based on the eyepieces available (interchangeable depending on the object to be observed – it is essential to choose the eyepiece based on the type of telescope, the type of celestial bodies you want to observe and your budget; there are several – and also very expensive – which allow for clear images thanks to their versatility.)