Orifice Darkroom

The orifice camera obscura is a cubic or parallelepiped (box)-shaped device that has a small hole in one of its walls, which are all opaque.

When an illuminated or luminous object is placed in front of the camera, an inverted image similar to the object is formed on the wall opposite the hole.

The light rays that leave the object towards the camera are references to determine the relationship between the height of the object, height of the image, distance between the object and the camera and the length of the camera.

orifice darkroom

The triangles ABO and CDO are similar, so we have the following relationship: a/b = x/y

x = object size (m)
y = image size (m)
a = object-camera distance (m)
b = distance between the hole wall and the opposite wall (m)

As the orifice camera obscura is formed by opaque walls, seeing the image formed inside is practically impossible for an observer outside the box. The wall opposite the hole (place where the image is formed) can be exchanged for tracing paper and thus it becomes possible to observe outside the box and soon you will be able to visualize the image formed due to the object.

The following figure illustrates a man (object) and its respective image.

1. A darkroom is 50 cm deep. It is directed towards a tree at a distance of 10 m. A 5 cm high projection forms on the bottom of the box as shown in the figure. How tall is the tree?

x/0.05 = 10/0.5
0.5.x = 0.5
x = 0.5/0.5
x = 1m

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