The pinhole camera is a simple camera that consists of a light-tight container with a small hole on one side. The hole, also known as a "pinhole", acts like a tiny lens and only allows a very narrow beam of light to pass through. This light falls on the opposite wall of the container and creates an inverted and miniaturised image of the subject in front of the pinhole.
Inside the pinhole camera there is normally a light-sensitive material, such as photographic paper or film, which records the image. The material must be held steady during the exposure so that the image does not blur.
The Exposure time depends on the size of the hole. The smaller the hole, the longer the exposure time must be in order to produce a sufficiently bright image. Typically, the exposure time ranges from a few seconds to a few minutes.
In contrast to modern cameras with lenses and electronic sensors, the pinhole camera produces a very soft and blurred image. This is due to the fact that the light passing through the pinhole is not focussed. Instead, the image is blurred due to the spread of light over a larger area.
To give you an idea of what a pinhole camera looks like, I have included a historical illustration of a simple pinhole camera (camera obscura) here:
