What would Galileo think?
July 29, 2011 8:09 AM   Subscribe

Would it be possible to make a telescope from two contact lenses?

HI, it's me -- one of MeFi's friendly neighborhood science fiction writers. Today's question involves optics. I'm writing a sequel to a story I published last year. A few decades after the events in that story, a rather warlike culture of tiny winged humanoids has developed inside the closed system. They have few resources. Some of their weaponry is made from the bones and teeth of the first story's lead character, as well as fillings from his teeth and pins in his leg (the result of his career in the military). However, I'd like them to have a telescope, if possible. Is it possible to make one from contact lenses? I'll take any suggestions for other possible technology they might have in their restricted environment, too.
posted by Guy_Inamonkeysuit to Science & Nature (14 answers total) 3 users marked this as a favorite
A few conditions need to be met.

They need to be farsighted (hyperopic) so the lenses would be the right shape (convex). Then you need the lenses to be of very different powers, so each eye needs to be much different than the other. In a simple telescope, you put the thin, low power lens at the front and the thick, high power lens at the eye. The ratio of these lenses determines the magnifying power/FoV.

My opinion: does not sound convincing - the telescope would see have such a tiny, tiny field of view that it would be like looking through a drinking straw, or perhaps less.
posted by fake at 8:20 AM on July 29, 2011

No. You need a lens or mirror with a long focal length, and an eyepiece with a relatively short focal length. The long divided by the short gives you the magnification.
posted by weapons-grade pandemonium at 8:21 AM on July 29, 2011

Also, frankly, I'm not going to read your story to find out what might be in their environment, so you might want to give some examples of optically active things that are laying around. To get you started: Perhaps a contact lens as the front element - thin, low power, and a drop of water for the rear element - thick, high power.
posted by fake at 8:22 AM on July 29, 2011

I was thinking exactly the same thing, fake. You'd have to get your eye really really close to the water drop.
posted by weapons-grade pandemonium at 8:24 AM on July 29, 2011

On second thought, I think the focal point of a spherical water drop would be inside the drop. So no.
posted by weapons-grade pandemonium at 8:35 AM on July 29, 2011 [1 favorite]

[Link to older story removed, this needs to not feel like "and go check out my writing", good intentions notwithstanding. Include some more specific details in a followup comment in here if you need to provide more context than what's already in the question.]
posted by cortex at 8:52 AM on July 29, 2011

I would assume rigid contact lenses and then fake's scenario would be possible. If you had both distance and close-up eyeglasses (not bifocals) you could probably make a much better telescope but that doesn't sound like something that you'd have available in your scenario. Perhaps glass salvaged from bottles and the like?
posted by tommasz at 9:10 AM on July 29, 2011

Nope... it's a closed system. Nothing was it it to begin with but one human being, one (alien) animal, and one (alien) plant, in a spherical enclosure orbiting an exoplanet. The plant provided sap on which the human and the animal fed, and absorbed their wastes. I got the idea from those little self-contained ecosystems containing some shrimp and seaweed inside a glass globe.
posted by Guy_Inamonkeysuit at 9:27 AM on July 29, 2011

My opinion: does not sound convincing - the telescope would see have such a tiny, tiny field of view that it would be like looking through a drinking straw, or perhaps less.

But it sounds like these are tiny people, so maybe that would be ok for them.
posted by vytae at 9:29 AM on July 29, 2011

They are about two inches tall.
posted by Guy_Inamonkeysuit at 11:00 AM on July 29, 2011

Can they just use the lenses from his eyes? Can you mummify an eyeball?
posted by DU at 11:20 AM on July 29, 2011

No... I need something more durable, that will last longer. That's why I thought of contact lenses. (I wear specs, but have never had contacts, so I'm unused to dealing with them.)
posted by Guy_Inamonkeysuit at 12:51 PM on July 29, 2011

Most people wear 'wet' contacts these days, which actually don't work if they ever dry out. The lens in an eye would be a lot more long-lasting, I think.
posted by delmoi at 3:22 PM on July 29, 2011

No, I think I'm on the wrong path with this idea, so I'm gonna dump it. But thanks, everyone.
posted by Guy_Inamonkeysuit at 5:06 AM on July 30, 2011

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