For a kindergarden (pirate) party, friends of me want to build together with the 4 year old kids a functional pirate's telescope for each of the kids. On the web I found full constuction sets, e.g. http://www.astromediashop.co.uk/Telescopes.html (I am not affiliated), but that is only half the fun than improvising and building with household things.
Does anybody has experience building a makeshift telescope using the cardboard tube from a paper kitchen roll, in particular which lenses to use and how to fix them?
The rolls are e.g. 25.5cm long and have an approximate diameter of 4cm. Ideally, we would need two fresnel lenses, I guess, but I am not sure which ones to choose, how to fix them nicely to the tube etc.
Looking forward to your ideas.
Edit: In the meantime, I also found View the Stars Through a DIY Telescope which just states:
[You neeed]: 2 convex lenses (you can get these from a pair of magnifying glasses or by ordering lenses online)
Finding suitable lenses (with right focal length, diameter, weight) is actually the hard part.
Thinking further how I recycle things from home, I got the rough idea to build water lenses but this is clearly out of scope of a kindergarden project, or is it?