Welcome to the Art of Photography. My name is Ted Forbes and today we're going to talk about the camera obscura. I figured this was a good subject to kick off our very first podcast with.
since the camera obscura really predates what we consider to be the origins of photography. Let me show you what a camera obscura is. When we think of the invention of photography, we really think back to the 1800s when guys like Fox Talbot were experimenting with early image recording. But actually, that's not really the birth of photography. What that is, is that's the birth of being able to record an image onto an emulsion that either sits on a piece of glass or a piece of paper to record that still.
But actually photography dates way back earlier than that with things like the camera obscura. In fact, there are records of people like even Greeks like Aristotle in the 4th century discussing this. Leonardo da Vinci discusses the camera obscura in his Codex Atlanticus.
And especially during the Renaissance, there are some contested theories that some portrait painters, people like Vermeer, were using kind of these light rooms to actually go in and trace the image. And that explained... We do know that there were experiments with optics going on at that time, and that would explain some of the great contrast in realistic detail from the artwork that was produced before the Renaissance.
But either way, I'm going to show you what a camera obscura is and how it works, because I think it really is the most basic, you know, this is how photography works and how images are captured. Okay, for this experiment, and I promise I won't turn into Mr. Science on every episode, but what we're going to do, and you can try this at home, it's pretty cool, you can take just a standard cardboard box, okay? I've got a cardboard box and I've cut a hole in it right here. So what we're going to do is I'm going to take a simple camera lens and we're going to stick it in that hole. And what I'm going to do is project an image or project light onto the back of the box.
This is how I'm going to do it. I've got a light bulb over here, and this is kind of a weird light and there's a reason I chose it. If you're going to do this at home, most light bulbs that you buy at the hardware store come with a white coating on it, and it's hard to see any detail through the white coating. I picked this example because it's a clear glass bulb and you can see the filament inside and you're going to be able to see that in a second. But it's pretty easy.
Basically what happens is when I turn this on, I am actually using, I've got some light going here. I'm going to put the lens on the front of the box and we're going to simply hold it up and you can see that the image of the light bulb is projected and you can see some detail of the stuff around the light bulb in this particular light projecting onto the back of the box. Okay?
Pretty simple. You might also, and it's harder to tell here because this is unconventional, but if you use a standard light bulb, you can see it. The image is actually projecting upside down. Okay.
And I'm going to explain that in a minute when we talk about pinholes. But essentially, there are three ways that you can manipulate light. Okay. The first one is reflection.
The second one is projection. And the third one is refraction. Okay.
Reflection is pretty easy because we see it every morning when we get up and look in the mirror. A mirror is simply a way of reflecting. It's an optical illusion where you have...
a smooth enough surface that's been optimized to have this optical illusion where you don't see the glass surface you see this artificial world beyond it which is the exact mirror opposite of what your world is that you're looking into. Obviously everyone knows what a mirror is. The other two ways of manipulating light, what we're using right here is refraction. We're using glass to manipulate the light to project the image onto the back of the box.
Now you can also use the third type of manipulation which is simply projection. Okay, now the other thing I've done to this box other than cut a hole in the front is I've actually taken a small pen and literally made a pinhole right here on the front of the box as you can see. It's really tiny.
It's a small pinhole. Okay, now what we're going to do is do the same experiment. Now obviously the lens was able to let more light in. This is called aperture. If you're not sure what that is, we'll talk about it shortly.
Anyway, basically this is a smaller hole, so it's letting less light in. But you can still see, actually, that if I put this in front of the light, that we can see the light projected, in this case, through the pinhole onto the back of the box with some detail. You don't necessarily need a lens to produce an image. Let me show you one other thing. We're going to take this a step further.
I've got just a regular white mailing envelope. Let's put this in here and see how this affects it. Okay, as you can see, it's now projecting onto the white envelope. The closer I move this white envelope towards the pinhole, okay, the smaller the image gets.
It stays on there. It stays in focus because we have such a small aperture opening, but you can see that the image actually is smaller the closer I get, and the further away I move, the bigger the image gets. This is what's known, boys and girls, as focal length, okay?
Now, lenses on standard cameras come in focal lengths, okay? So, if you have the short Through the focal length, the wider the angle you're going to have. Let me explain how this works because it's kind of the opposite of the way things appear in real life.
The closer something is, the bigger it is, right? It's the opposite through the pinhole or through the lens too. But anyway, when I'm really close, you can see it's really small. So more of the scene is going to be projected onto whatever you're projecting onto it, be it film, this envelope, or a CCD in a digital camera.
Anyway, you're going to get more of the scene on there. The further back I go, or the longer the focal length, I end up with kind of a macro or telephoto effect. So that's how focal length works. So essentially that is the camera obscura, and we did it with two methods here. We used refraction to project our light onto the back, and we used standard projection to project the light on the back.
In both cases, that image was upside down, and we know that because light, we know, travels in a straight line. So for instance, the top of the light bulb has to come down to go into the pinhole, the bottom of the light bulb has to come up to go through the pinhole. Okay.
So if you continue up with that line, once it hits, comes through the pinhole and hits the back of the projection surface, in this case, it would be on the top and not the bottom and vice versa for the top. So that's why you end up with a completely kind of inverted image, if you will, when you look through here. So anyway, so that's how that works.
In the next episode, we're going to talk about pinhole photography, which really I get excited about because pinhole photography is one of the most kind of early examples of... of photography. It doesn't require lens. It's very low-fi. You can get some really interesting effects with images and it's very inexpensive and easy to do.
You can make your own cameras even. So anyway, that'll be next time, but that's all I got for today. Thanks for watching.