By Debby Venable
Oklahoma STEM Ambassador
Millions of pictures are taken across the world everyday. Everyone wants to record “that special moment” to remember at a later time. We are the picture takingest family that I have ever seen. Of course having a first granddaughter doesn’t make it any better. We save everything Madison does for posterity. So naturally I love to put cameras in everyone’s hand to see the world through a different view or “lens” as they say.
What a better way to acquaint students with the principles of light, the eye, and cameras than to study a pinhole camera and how it resembles the human eye. I always try to cover this with my students when we talk about taking pictures, just like our eyes do each and every day.
So when the eyes look at an object, it will reflect the same images that you will see when you build a pinhole camera. It is very simple to build and your kids will love the parallel between the workings of your eye and your pinhole camera. I feel another one of those “teachable moments” coming on.
The pinhole camera is a mere teaching tool to educate our students about light and the human eye. Let the kids experiment and figure this one out on their own. I think you will be surprised.
SMILE …. SAY “CHEESE”
Your eyes, and the eyes of many other animalsand insects, work the same way as a pinhole camera. Building your own pinhole camera will help you understand how this works. This is a great teaching tool for you in the afterschool program.
Take an empty Pringles Potato Chip can and wipe out the inside so it is clean. Cut off the bottom two inches of the can with a sharp knife (you might need your mom or dad to help with this part).
The short piece has a metal bottom. Use a thumbtack to make a tiny hole in the center of the metal bottom. That's where the light will come in: it's like the black pupil in the center of your eye.
You're going to use the plastic lid as a screen, like the movie screen that the picture projects on to, or like the retina inside your eye. If the plastic lid on your can is translucent (light comes through but you can't see through it), you're good to go. If it's transparent (you can see through it), then you should tape a piece of wax paper or tissue paper to the lid.
Put the lid on the short piece, to make a short Pringles can. Now put the longer piece on top of the lid, so you have an open Pringles can with the lid blocking the middle of it. Tape it all together.
You need to keep all the light out of your camera, so roll your tube in some tinfoil twice around, and tape the foil on. Tuck the end of the foil over the open end of the tube. (You can also add a foam soda can holder over the open end of the can, to help keep light out.)
Take your camera outside on a sunny day. Hold the open end of the camera up to your eye. Make the inside of the tube as dark as possible. Can you see an upside-down picture of the outside on your plastic screen? Your eye also makes upside-down pictures on your retina, but your brain learns to flip the pictures right-side-up without your even thinking about it.
This is a great science experiment for kids that is a lot of fun, easy to do, very inexpensive, and showcases some important principles of light and vision. My parents helped me put one of these together back when I was in the second grade, and I still have the camera - It is just as cool now as it was back then!
WHAT YOU'LL NEED FOR THIS EXPERIMENT:
* A cardboard cylinder - An empty oatmeal canister works perfectly for this science experiment.
(If you are looking to make a more permanent pinhole camera, use a small wooden, 5-sided container or cylinder instead of cardboard.)
* Parchment paper (printer or wax paper will also work)
* A rubber band that is large enough to stretch around the container
* Something to poke a hole in the container (A pen, screwdriver, or long nail works great. Make sure there is adult supervision with the sharp objects if you are working with young kids.)
PUTTING IT ALL TOGETHER:
* Step One: Poke a hole in the bottom, center of your container. If you are using cardboard, this is a pretty easy step, and can be done with something as easy to find as a ballpoint pen. If you are using wood to make a more permanent pinhole camera, you'll want an adult to drill a hole in the bottom, center of the wooden container.
* Step Two: Cut out a piece of parchment paper that is big enough to cover the opening of the container. The parchment should be stretched tight, and should completely cover the opening of the container.
* Step Three: Stretch the rubber band around the opening of the container so that it is holding the parchment paper tightly in place. By this step, your pinhole camera should resemble a drum.
* Step Four: Stand in a dark room, and point the bottom of the container out
the window towards a brightly lit tree, building, or some other brightly lit scene. When you look at the parchment, the scene coming through the pinhole will appear upside down.
WHY DOES THIS WORK?
This science experiment works off of some important principles of light and vision. When light rays travel to our eyes, the rays go through the pupil and lens, and produce an inverted (upside down) image on the retina. Then, the image is turned right side up again by the part of our brain that manages sight. When you use a pinhole camera, the image you see projected on the parchment paper is actually what your eyes see before your brain flips things upright.
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