The Camera Obscura: how does it work?

Maria Short knew!

The Camera Obscura is a darkened room or chamber into which light is directed to enable you to see a mirror image of the view outside. In our case, you can use it to tour the city of Edinburgh.

A History of Camera Obscuras

Camera Obscuras date back a long time, possibly even before records existed.  The first actual record of something like a Camera Obscura dates back to Ancient Greece, when Aristotle noticed that a partial eclipse could be safely viewed by looking at the ground underneath a tree. The tree’s canopy created a nice, dark space, and the tiny holes between the leaves allowed light to pass through and ‘project’ a mirror image of the sky onto the ground.

In the 16th century, artists made use of the Camera Obscura to produce drawings with perfect perspective. For more on that, see our previous blog post about Vermeer and his use of the Camera Obscura here.

In Victorian times, larger Camera Obscuras became popular seaside attractions, allowing groups of people to experience the phenomenon together. The live images were a great source of entertainment.

Seaside Camera Obscura

Seaside Camera Obscura

It was in 1835 that Maria Theresa Short first set up Short’s Popular Observatory on Calton Hill, exhibiting the Camera Obscura as the first, purpose built attraction in the city of Edinburgh. In 1853 Maria moved to Castlehill with the Camera Obscura and it has been running here ever since.

Shorts Observatory 1870

Short’s Observatory 1870

In 1882, Sir Patrick Geddes bought the tower in a public auction. He renamed it the Outlook Tower, deciding to refocus the Camera Obscura away from tourism and onto education and philosophy. He would rush people up the five flights of stairs to see the Camera Obscura. It was believed that this race to the top would stimulate blood flow and oxygen to the brain – opening peoples’ minds and allowing them to get more from the experience.

Outlook Tower Brochure

Outlook tower brochure

Edinburgh University owned the tower from about 1940, during a quiet time for Camera Obscura. It was then sold to us in 1982, heralding the renaissance for entertainment, education and innovation for the Camera Obscura.

Our Camera Obscura

Our Camera Obscura

How It Works

At the top of the tower there is a plain mirror, protected by a hood and a pane of glass.  The mirror is angled so that natural light reflects downwards, into the tower. The light passes through the three lenses, which enable it to focus onto the table.  The lenses also switch the image so that it appears the right way up on the viewing table.  When the room is darkened, our eyes adjust to the light and we can then see the reflected image.

Top ofthe CameraObscura

Top of the Camera Obscura – showing the mirror and first lens.

 There have been a few changes to the original Camera Obscura here. In the beginning, there was only one lens, and the original table was even higher than the current one, so the distance between the lens and image was much smaller. The original picture was also smaller and less clear than it is now.

Nowadays there are three lenses and the first lens is almost thirty feet from the table. These lenses focus light in a curve. To compensate for this, the table is concave, so that images do not appear warped.

The view

The view from up here…

 By today’s standards, the technology involved in the Camera Obscura is incredibly simple; no pre-recordings, no cameras, not even any electricity. Despite this – or perhaps because of it – Edinburgh’s Camera Obscura has continued to entertain the public for over 160 years.

Want to see it in person? We are open every day from 9.30am to 8pm during the school holidays.


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