Intro: Pinhole Camera Explained
Hi there! I'm Melody, and I'm 13. I've always loved science, but recently we had to do this science project for school and I decided to record every step of it. Our project was recreating how a pinhole camera worked, or simply put : making a simplified version of it. My 7 year old sister loved watching the whole thing, and I thought that if she enjoyed it; maybe other kids will enjoy it too. Also at the same time, tiny kids could learn a bit of middle school science!
I'm sorry if this is all a bit too long, I just tried to break it down as much as possible. If you only want to understand it and not make the whole thing, just skip to the last step.
Step 1: Stuff You Might Need
Double-sided tape (or just tape if you don't have any)
Compass, the type you use to draw circles
Step 2: Making a Simplified "Pinhole Camera" - Part 1
1. Take a peice a black card, and make tube out of it. Mine was about 8cm wide, and 12.5cm long.
2. Cut out a round peice to cover one end of the tube, this is the side where you poke a teeny tiny hole (the pinhole) to let the light pass in. If you used a compass to draw the circle, you'll already have a center marked for you, just poke right through it. I'll explain more about this at the end.
3. Glue your round peice to one end of the tube with a touch of glue, and your half way done!
Step 3: Making a Simplified "Pinhole Camera" - Part 2
So now it's time for your other end.
1. Draw 3 circles in and out of eachother, like the picture above.
2. Cut the outer and inner circles, leaving you with a donut shape, the distant between the 3 circles doesn't have to be exactly like the measurings in the photo, the "1cm" part, just has to be enough for your paper clips to be clipped on.
3. Glue the ring to the tube, matching the line of the middle circle with your tubes' width.
Step 4: Preparing the Experiment
And you're done! With the "camera" part, at least. The first photo is what my finished product looked like. In case you're confused, the line of glue around the middle is there just because the tube was too long at first, and I had to shorten it up. Just ignore it!
The second photo is a couple of templates I made to put over an LED torch (flashlight, if you're in the US), this is just a little add-on if you want more than a candle flame to look at. If you want to know more about this step, just let me know in the comments!
And last, trace the outline of your open top(the outline of your black ring part) on some tracing paper, and cut them out. These are gonna be your projection screens.
Clip on one of your projection screens to your open top, and with the measurements you made whilst drawing the ring, it should all fit perfectly. (The last photo)
Step 5: Experiment Setup
To actually do the experiment, you'll need 3 crucial things:
A pencil, so you can trace down what you see
A candle, and of course a lighter
If your setup looks like one out of the last 4 pictures, then you're ready. In the last 3 pictures though, I've added a ruler, this way, I can roughly measure out the distance between the flame and the pinhole, thus proving this theory we were learning about:
If the "flame to pinhole" distance is shorter than the "pinhole to projection" distance, the projected image should be bigger than the actual flame; If the "flame to pinhole" distance is longer than the "pinhole to projection" distance, the projected image should be smaller. And if the "flame to pinhole" distance is the same as the "pinhole to projection" distance, the projected image should also be the same size as the actual flame.
Phew! Glad we got THAT over with.
Step 6: Experimenting
Turn the lights off, and enjoy the little upside-down flame dance just for you. Trace out the outlines of your flame every time before you move the candle to a different distance, but of course change out the pieces of tracing paper every time. If you want, you can also record the process and post it on instructables to prove you're a proper science geek!
Step 7: Explanation
The whole point of doing this experiment, was to prove the theory I mentioned in step 5, and also to prove that light never bends around (for example:shadows). In the picture above, you can see that, for the light to pass through the pinhole, in has to be slanted, but also because it never bends, it can only keep going forward, and what used to be light from the tip of the flame, will eventually end up being lower, and the light from the bottom, will end up higher, making the projected image upside-down.
And just think, if the candle and the pinhole is super close, the light will have to be super slanted to force it's way through the pinhole, and when the "straight" light keeps going, the 2(top and bottom) "lines" will have to get further and further away from each other, and when it ends up on the projection screen, it'll obviously be a bigger projection.
And that's it! You've pretty much understood the basics of how a pinhole camera works! The bigger-and-smaller/closer-and-further part might be confusing, so I'll try and get another picture up here explaining it asap.
If you've got any questions let me know in the comments, and I'll try to answer them with all my effort. Until next time, thanks for reading and gooooodbye!