How does a refractor telescope work?

A workshop where you understand optics by building it with your own hands

Rather than explaining optics on a blackboard, we let people assemble it. Module after module — objective, baffle, tube, focuser, star diagonal, eyepiece — each participant builds a real refractor telescope and discovers, live, what every part is for and how the image is formed.

A workshop we have been running for years at public events, notably at the Cité de l'espace for the Night of the Stars, at festivals and in schools.

General public, ages 6+

Real telescopes, not mock-ups

Drop-in or scheduled sessions

Turnkey, we bring everything

Request a free quote

Telescope assembly workshop at the Cité de l'espace

How the workshop runs

1. The starting question

How can a simple lens bring the Moon closer? We start from what participants actually see, with no prerequisites and no technical jargon.

2. Module-by-module assembly

Each module only fits one way: getting it wrong is impossible. With every part added, we look at how the image changes.

3. Understanding

Objective, baffle, focal length, eyepiece, star diagonal: the role of each element becomes obvious once you have held it in your hands.

4. Observation

We point the assembled telescope: the Moon and planets in the evening, a distant target or the Sun (with a proper filter) during the day.

The workshop at the Cité de l'espace — Night of the Stars 2026

"Build your own telescope" workshop at the Night of the Stars

$Participants assembling a refractor telescope$ Explaining the role of the lenses during the workshop

Astronomy workshop for all audiences at the Cité de l'espace

Family optics workshop at the Night of the Stars

La 3ème Dimension stand at the Cité de l'espace

$Assembling a refractor telescope during the workshop$ Observing with the assembled telescope

Night of the Stars 2026 at the Cité de l'espace

Practical information

Format

Audience	General public, recommended from age 6
Duration	From 15 min per participant to a full evening
Setup	Drop-in and continuous, or guided sessions
Participants	From a handful to several hundred over an evening
Language	French or English

What we bring

Instruments	Complete telescopes to assemble and disassemble
Staff	One or more facilitators depending on attendance
Equipment	Supports, signage and workshop material
Setup	Stand set-up and take-down included

Venues and contexts

Events	Night of the Stars, festivals, science fairs
Schools	Primary, middle and high schools, field trips
Culture	Libraries, museums, planetariums, astronomy clubs
Companies	Seminars, family days, team building
Area	Toulouse and Occitanie first, anywhere in France on quote

Workshop on quote

On quote

The price depends on duration, number of participants and location

Preparing the workshop with you beforehand
Facilitator(s) for the whole duration of the event
Complete refractor telescopes provided
Workshop material and stand set-up
Content adapted to your audience
Travel and logistics

Request a free quote

Just tell us the date, the venue, the expected audience and the duration you have in mind, and we will come back to you with a tailored proposal.

Options

Sky observationAdd an observing session with our instruments, depending on weather and the time of the event.

Solar observationDaytime session with a proper solar filter to observe the Sun safely.

School sessionFormat adapted to the curriculum and to class length, with several groups over the day.

Kit left on siteOption to keep one or more Lumi telescopes so the activity lives on after we leave.

Questions fréquentes

Do participants need any astronomy background?

None at all. The workshop is designed for complete beginners: you discover how a telescope works by building it, with no technical vocabulary required.

What age is it for?

Recommended from age 6. Younger children assemble with help from an adult or the facilitator, and adults are often just as captivated as the kids.

How many people can you host?

It depends on the format. Running drop-in and continuous, we welcome several hundred people over an evening, as at the Cité de l'espace. In a school setting, we work class group by class group.

Do participants keep the telescope?

By default no: telescopes are assembled and then taken apart for the next participant. We can arrange Lumi kits to be given or sold on site — just mention it when asking for a quote.

Do you travel across France?

Yes. We are based in Toulouse, so Occitanie is the easiest to arrange, but we travel anywhere in France — travel is then included in the quote.

What happens if the weather is bad?

The assembly workshop works indoors as well as outdoors and does not depend on the sky. Only the observing option depends on the weather.

How does a refractor telescope work?

How the workshop runs

1. The starting question

2. Module-by-module assembly

3. Understanding

4. Observation

The workshop at the Cité de l'espace — Night of the Stars 2026

Practical information

Format

What we bring

Venues and contexts

Workshop on quote

Workshop on quote

Options

Questions fréquentes

Our other products

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