What happens when you take some binoculars apart?

Our Exploring Binoculars program today was a blast! Investigators ranged from about 7 to about 65 years old. It was a technical sort of program, more about how they work than about how to use them. We did a little demo/inquiry first,  with light and lenses and prisms, asking “What might happen if …” questions and then doing that to see what really does happen. Fun seeing upside-down light bulb images on tissue paper become reversed on sweatshirts! (See that “how they work” link for what we did.)

Then we laid out some defective binoculars donated for the express purpose of disassembly (cleaning and reassembly optional). Each set of binoculars came with a handout, too, that asked the kid, adult, or kid-adult pair to observe and ask questions.

Some of the things we asked:
How do the lenses work?
How does the distance between prisms affect what you see?
Why do the eyepieces and objective lenses not line up with each other like a telescope?
Why does one side magnify things when you look through it, but the other side makes things look far away?

We had guidelines for disassembly, but as our models varied, we didn’tmake thisprescriptive: each team worked it out as they went along. yes, we talked a bit about safety (glass, metal, eyes, bad combo, etc.)! We based disassembly on several online how-to examples: www.ehow.com/print/how_10050098_disassemble-binocular-lens.htmlwww.ehow.com/print/how_6464218_disassemble-binoculars.html, and www.scribd.com/hrrrose5481/d/11912773-Binocular-Disassembly1.

Notes (for when we do it again): Heavier-duty binoculars were more possible to take apart than cheaper ones (more screws, less glue) but had many more pieces. We jury-rigged something (as we hadn’t found a good the spanner wrench) to help remove objective lenses. We were surprised by the objective lenses: they were not as simple as we thought they’d be!  A small strap wrench might’ve been handy, but strong hands and forearms worked well too. Good-quality jewelers/eyeglass screwdrivers are a must. So are trays, to keep tiny screws from vanishing.

We did run out of time to formally answer our questions together. (It happens!) Looking back, however, I can see that all could be answered by either what we were doing or by messing around with the parts after we took them apart. Very, very cool.

We’ll need more old useless binocs to do this again, but we’ll do it if we get them. Let us know if you have some!

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