Aberystwyth sands seen through the camera obscura

In the previous article of this series, we delved into the fundamentals of light and photography. Now, let's take a step back in time and explore the Camera Obscura, the precursor to the modern camera, and the physics of image formation that laid the groundwork for today's photographic techniques.

The Camera Obscura – A Historical Perspective.

The Camera Obscura, Latin for “dark chamber,” is an optical device that dates back to ancient times. It consists of a darkened room or box with a small hole or aperture on one side. When light passes through this aperture, it projects an inverted image of the scene outside the room onto the opposite wall. The Camera Obscura played a significant role in the development of modern photography, as it helped early pioneers understand the principles of light and image formation.

Aberystwyth sands seen through the camera obscura
Aberystwyth sands seen through the camera obscura by Ruth Riddle is licensed under CC-BY-SA 2.0

Role of Lenses in Focusing Light.

Lenses are crucial components of both the Camera Obscura and modern cameras. In the Camera Obscura, the small aperture focuses light to create a sharp image on the opposite wall. However, this process also limits the amount of light entering the chamber, resulting in a dim image.

In modern cameras, lenses play a similar role, gathering and focusing light to form an image on the camera sensor or film. Lenses are made of glass or plastic elements, carefully shaped to refract (bend) light rays so that they converge at a specific point, known as the focal point. By adjusting the distance between the lens and the sensor or film, photographers can achieve a sharp focus on subjects at varying distances.

The Process of Image Formation.

Image formation in both the Camera Obscura and modern cameras relies on the same fundamental principles of physics:

  1. Light enters the camera through an aperture: In the Camera Obscura, this is a small hole, while in modern cameras, it is an adjustable diaphragm within the lens.
  2. The lens focuses the light: In both cases, the light is focused to form an image. In the Camera Obscura, this is a dim, inverted image on the wall. In modern cameras, it is a brighter, focused image on the sensor or film.
  3. The image is captured: While the Camera Obscura's image is temporary and visible only within the dark chamber, modern cameras capture and store the image on a sensor or film, allowing for permanent records and reproduction.


The Camera Obscura and the physics of image formation are vital foundations of modern photography. Understanding these principles helps photographers appreciate the intricate interplay of light, lenses, and image capture that brings their creative visions to life. As we continue this series, we will delve into the details of shutter speed, aperture, and ISO, further expanding your knowledge of photography's fascinating world.

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