What is stereoscopy?

Home » Early Stereoscopy 1838-1870 » What is stereoscopy?

Stereoscopy is a technique to create the illusion or perception of depth when viewing stereoscopic images. Humans have two eyes and the small perspective differences between the left and right eye are interpreted by the brain as “depth” and so we experience a three-dimensional world.

With stereoscopy it is possible to simulate this process. The most popular way to create stereoscopic images is with a camera. With a regular camera, a photo is taken and then the position of the camera is shifted slightly to take a second photo. The distance between both positions is the stereo baseline.

The result is two nearly identical photos with only a slight difference in perspective caused by the two different camera positions. The two pictures are called a stereo pair.

A developed stereo photo or stereoview with a size of 8,5x17cm
A stereo pair. The right image shows at the right side a part of a building that is not visible in the left image. This is due to perspective differences caused by different camera positions.

A stereo camera has two lenses and the lenses are mounted at some distance from each other. The distance is comparable to the distance between the two eyes of a human (about 6,5cm). With a stereo camera, the two images can be shot simultaneously, without having to move the camera position.

Vérascope stereo camera
Vérascope stereo camera

A developed stereo photo is called a stereoview. There are several ways to view a stereoview in 3D. This website focuses on the most commonly used method that fits the themes and time period of this website: by using a stereoscopic viewer, better known as a stereoscope. The stereoview is placed in the stereoscope and viewed through two lenses. The viewer now sees the image in 3D.

Early hand-held stereoscope
Early hand-held stereoscope

Stereo photography is still practiced in the digital age, but today it is a photography niche. However, it had two major waves of popularity between 1851 and 1930.

Images © André Ruiter 2018 - 2022, unless otherwise stated.
Content may not be used without permission.