So, did you like the result of this camera obscura? So I'm going to show you in this video how her construction tutorial was. First, you will need a can, and it can be milk, a piece of parchment paper, the lid of the can to hold the parchment paper to the can, a nail to make the hole where the light will enter and a hammer .
You will also need a ruler and a pen, scissors and a knife, masking tape, black cardboard, which is better than cardboard because it is very soft and to improve the effect I also used a matte black spray . To make the construction, first we have to find the center of the base of the can using a ruler and marking it with a pen, then we make the holes. If you want to get enough clarity to project the image into your darkroom then you will make a bigger hole, but if you want more definition for your image's resolution , more sharpness, then it's better to use a small nail.
Before painting cans, it is always good to sand them so that the paint has greater adhesion. And the advantage of painting the can from the inside is that sometimes the light that comes from outside can enter and be reflected inside the can, interfering with the visualization of the image that is projected on the tracing paper. Here I'm going to make a cut in the lid of the can so that it can better fix the tracing paper, but you can also use the masking tape itself.
So I'm going to remove the works from tracing paper with scissors and the cardboard has to have the black part to the inside because this color will also help absorb more of the light that I want to be reflecting inside, interfering with our visualization. Here I used a bicycle chamber elastic strip to better fix the cardboard to my can, but there is no such need, you can also use masking tape. And taking this camera obscura to look through the house window, then you can see that this projected image on tracing paper has a characteristic of being inverted vertically and also inverted horizontally.
But what do you mean Kobax, why does this happen? So I'm going to take my camera obscura apart so you can understand what's going on. It is through this little hole I made with a nail that the image will be formed here on the tracing paper and this image will be inverted because all the light that has come from above will pass through the hole and arrive here at the bottom of the tracing paper , while all the light coming from the bottom will pass through the hole and be projected here on the top of the tracing paper, while the light coming from the right, it will cross the hole, it will reach the left, and the light that comes from the left will enter the hole and will be projected on the right.
And that's why we see this inversion both vertically and horizontally. And that's why this experiment is often used as an experimental verification of the principle of straight light propagation. Got it, but what's that for?
You can use the camera obscura in order to determine which is the distance that we are to a building for example, or even what is the height of this building. But to do this you will need to square this tracing paper both horizontally and vertically 1 in 1 cm. And to make these lines you can use a black pen.
So imagine you're here looking into your camera obscura and here's its orifice. So and you want to see this tree through the darkroom. This tree will emit rays of light from all points on it in all directions and some of these rays will enter through the darkroom.
I'm going to choose a ray of light that comes out here from the upper end of my tree and reaches the bottom of the darkroom and I'm also going to choose a ray of light that comes out here from the base of my tree, it will pass through the darkroom hole until reaching the tracing paper. If we consider that the height of this tree is parallel to the height of the projected image here at the bottom of the darkroom, we can consider that these two triangles are similar, then we can apply a proportion rule, for example, let's assume that my can has 12 cm and this image was formed here with approximately 6 cm. This means that if I have this distance from my camera obscura to the tree and this distance is, for example, 10 meters, then I can estimate what the value of the height of this tree X should be , and then I could apply a similarity of triangles to this case, for example 6 divided by 12 will be equal to X divided by 10.
And solving this account we have what then? 10 times 6 is 60 and divided by 12 is 5, so our X is going to be, if here I have centimeter and centimeter, then here I have meter and meter. So I'm going to have 60 divided by 12 = 5 meters.
I didn't even need to apply this rule of three or this aspect ratio because actually if I know the height of my image is half the size of that distance, then that height of the real tree is also going to be half that distance, so 5 meters. And the last tip for you is that when we use the darkroom, it can often be that too much light is coming in, interfering with our visualization of the image projection on tracing paper, in this case, one thing you can do is what the photographers do. in the past, they did it to be able to see the photos better, they used a blouse or a darker plane to see the image projection more clearly, without interference from outside light.
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