How to Make a Telescope

About: I am 18 years old and love to hack and fix stuff.

I have always wanted to observe the stars, but the equipment was pretty expensive.Have you been fascinated by the stars in the sky?Did you want to get closer to them?Did you ever want a telescope but it was too expensive?
Well here's your answer to all these questions:-How to make a telescope!!!

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Step 1: Parts

These are the essential parts and tools needed
1.2 lenses
2.Hot glue gun
3.Thick Black Paper
4.Black Tape (any kind)

Step 2: Lenses

Buy two magnifying glasses.the first should have a large diameter and less magnifying power(2X,or 3X).The second should have small diameter and large magnifying power(6X or 8X ,the larger the better).

Break the magnifing glasses to obtain the lenses.Break the magnifing glass carefully ,I broke a lens like this .

Step 3: Setup

Roll the black paper to form 2 tubes ,the first should fit the larger lens and the second should be able to slide inside the first one.
Now the sum of the lengths of your 2 tubes should be more than the sum of their focal lengths.To figure out their focal lengths solve this equation-  

Focal Length(cm)=                25                 
                                       Magnifying power                                 

*Magnifing power(2X,8X,etc.)

Step 4: Attaching the Lenses

Hot glue the lenses on to their corresponding tubes.Make sure the two tubes slide into each other (refer to pic).This is the most crucial step in the entire instructable.
TIP -While hot glueing make sure not much of the glue falls on the lens.This ruins the lens.

Step 5: Enjoy

The image formed at small distances will be inverted.But for Astronomy it doesnt really matter whether the planet is upside down or not.This same design was used by Galileo until be built his own design which made upright view.
To calculate the magnifing power of the telescope:-
M=     focal length of front lens      
        focal length of second lens

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    26 Discussions

    I ended up with a magnification of 3.Remember this is angular magnification so if initial angle of observation is 30 degrees it will become 90 degrees


    Question 4 months ago

    Is it possible to make a telescope with two similar size convex lenses having 100cm and 20cm as their focal lenghts ?


    1 year ago

    Nice. I am making a demonstration speech on how to make a telescope and this helped me out alot I got a A- on my speech!!! thank you so much!!!!!!!!


    2 years ago

    Can you please tell me does the type of lens matters. I mean convex or concave or ...................

    I have mostly focal length within 10


    3 years ago

    very good!


    3 years ago on Step 5

    We're about to do this I hope we can make it for our science proj. btw, thanks for the info. :)

    Emma Hunt

    4 years ago on Introduction

    how to beak the magnifying glass to obtain the lens? i can't see the photo here...