Create your own camera obscura


After working through this chapter, you should be able to:

  • Explain how a pinhole produces an image

  • Create your own camera obscura


As we discussed very briefly in chapter 13 , a ‘camera obscura’ is an imaging device that utilises the theory behind pinhole photography. When light emanating from an object shines through a pinhole, it produces an upside-down image. This is because light rays from the tip of the object (e.g. the top of the mug in Fig. 18.1 ) travel in a straight line through the pinhole and end up near the floor, whilst light rays from the base of the object travel in a straight line through the pinhole and end up near the ceiling. When these rays form a focus, it necessarily produces an inverted image.

• Fig. 18.1

Diagram showing path of light rays from a mug, producing an upside-down image in a pinhole camera. The image is also flipped left to right, so in the image (on the right), the text will be facing the other way (which is why it’s missing).

The experiment

In order to see how this works, it’s best to make our own. To do this, we’ll need a pinhole aperture and something to project the image onto ( Fig. 18.2 ).

• Fig. 18.2

Illustration of required materials.

Equipment required

  • A pencil

  • A drawing pin/needle/something with which to make a very small hole

  • Two pieces of A4-sized black card (if you don’t have black card, a cereal box might do)

  • Tape of some kind

  • Scissors

  • Tracing paper or equivalently translucent material that, when held up to a lamp, is diffusely illuminated but does not show a clear image of the lamp through the material (e.g. a translucent sandwich bag or the bag from inside a cereal box – if these are too transparent, you can double up the layers)


Feb 6, 2023 | Posted by in OPHTHALMOLOGY | Comments Off on Create your own camera obscura

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