We've been having some really great weather lately- much more spring than winter- so we've been trying to get outside as much as possible after being cooped up inside for a couple of months. The other day we went for a walk; the weather was warm, the birds were singing, and the kids were trying to spot them all in the trees. And that made me think that we should have some binoculars to help us spot them. So we decided to make some.
At first I was just going to pull out my stash of toilet paper tubes, let the kids decorate them, and then glue them together, but I thought it would be interesting and more fun to make some binoculars that actually work. So we did!
Really quickly, here's the science behind how this works: binoculars use lenses (curved pieces of glass) to draw distant light rays together to bring them into focus. There are two types of lenses- concave and convex. Concave lenses are curved so that the middle is thinner than the outer edge, which forces light rays to spread out as they pass through. Concave lenses are used in things like movie projectors to make light cover a larger area. Convex lenses are sort of dome shaped, with thinner outer edges and a thicker middle. As light passes through convex lenses, the rays converge, making objects appear larger. Convex lenses are used in things like magnifying glasses and, yep, you guessed it! Binoculars.
Binoculars actually use two convex lenses. The first lens catches the light rays and makes them converge, creating an image, and the second lens magnifies it, making it look larger and closer. So, how did we make our binoculars?
Well, first, I DID pull out the TP tubes and let the kids decorate them.
When they were done coloring, decorating, etc., I punched a hole in the top outer edge of each side, glued the two tubes together, and tied some yarn through them for a neck strap.
I bought some 2 1/4-inch magnifying glasses from the local party store, removed the handles, and glued one lense to each opening (two per TP tube), making sure that the curved part of each lens was facing into the tube. If you look at the picture, you can see that I didn't originally remove the little plastic tab that held the lenses into the handles. I went back afterward and used a pair of very sharp scissors to cut them off.
It is worth mentioning here, that we used very cheap magnifying glasses, which work, but are quite blurry. Your binoculars will only work as well as the magnifying glasses you choose, so the better the lens, the better the binoculars! You may also want to play around with the placement of the lenses. We glued ours to each end, but they may work better if they are placed closer to each other; for example, one lens on the outward-facing end, and one lens just behind it inside the tube.
And that was it! We took them outside to play with and search for birds.