This experiment is something that I ran into MANY years ago when I first began wearing glasses. If you wear glasses, then you know how challenging it can be to find your glasses if you have laid them down and can't remember where you put them. You need your glasses to find your glasses. This is a way that you can make a quick, emergency pair of glasses for yourself or someone else that needs them.
You will need:
- someone that needs glasses
- a piece of stiff paper
- a needle, pin, or sharp nail
If you wear glasses, take them off. Look around you. Things probably look very blurry. If you don't wear glasses, get a friend that does wear them to try and read something without their glasses. Note how close or how far away they can read something.
Now we are going to make some paper glasses. Put your glasses back on if you need them to see up close. Use the pin to make a small, round hole in the piece of paper. Hold the paper up to your eye and look through the hole. If you normally wear glasses, you may be in for a surprise. Things look almost as clear as they do with your glasses. They will look dimmer, but very sharp and clear.
What is happening? In other experiments, we have used a pinhole as a lens to focus an image onto some waxed paper with our camera obscura, and to focus the Sun's image to watch an eclipse. Here we are doing the same thing, but instead of focusing the image onto paper, we are focusing it onto your eye.
To understand how the pinhole works, you will need to make another pinhole, very close to the original. Now as you look through, you will see a double image of everything. Add 5 more pinholes and the image begins to blur as you get more and more images overlapping. If you add enough pinholes, things will look the same as they do without the pinholes. Think of looking at things without your glasses as looking through a tremendous number of pinholes all side by side. Using a single pinhole only lets a single image through, so it is dim, but in focus.
In an emergency, you can even do without the paper. Put the first finger and thumb of your right hand together, as if you were pinching something. Do the same with your left hand and then bring your hands together to form a small opening between your fingers and thumbs. Look through this tiny hole and it will work just as your pinhole did. I have even seen adds in novelty catalogs for emergency glasses which were actually just cardboard glasses with cardboard lenses. Each lens had several pinholes in it. A neat idea, but not at $19.95.