What is Stereoscopy?

What is Stereoscopy?

Well, it’d be a bit naughty to start a blog about stereoscopy and not say what it is!

In a nutshell: Stereoscopy uses the illusion of depth to create a single 3-D image from two flat images when viewed by each eye separately.

WHAT IS STEREOSCOPY?

Stereoscopic pictures are a pair of images showing the same scene or object from two slightly different angles corresponding to the angles of vision of the two eyes of a person looking at the object itself. Relying on binocular vision, the left image is presented to the left eye and the right image is presented to the right eye, the brain then interprets the two separate images, combining them in terms of depth… et voilà… you can see the image in its stereoscopic 3-D glory. Usually when a person first sees a stereo-image in 3-D you know it’s worked when you hear the “WOW!”

StereoviewExampleReduced
An Example of a Victorian Stereoview

HOW TO VIEW STEREOVIEWS

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How each image is presented to each eye separately can vary. Some people can ‘free-view’ just by looking at a stereoview (of the correct size) and many say it works by looking through the images. Usually this takes practice and experience and much boasting when successful. Some people switch the images around and go cross-eyed to cross view, you look a little silly but you’ll be pleased to know that the wind can change and you don’t stay like it.

3-D VIEWING DEVICES

10-Owl VR Kit
A London Stereoscopic Company’s OWL VR Kit

An easy way for viewing stereoviews is by using a stereoscope, there are many options both new and old – a quick search on Ebay for example will show there are lots. My personal favourite for using with standard-sized stereoview cards, my smartphone and many books is the London Stereoscopic Company’s Lite OWL but there are several other manufacturers. Just be cautious though that the viewer is the right size for the stereoview you want to look at, View-Master reels need a View-Master stereoscope, Lestrade cards need a Lestrade viewer, etc. You can also use the red and cyan glasses for red and cyan anaglyph images, polarising glasses for passive projecting and shutter glasses for active projecting….OK I’m getting a bit too nerdy, but the idea is there are several ways to view stereoscopic 3-D.

TAKING 3-D PHOTOGRAPHS

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A 1950s Stereo Realist Camera

Stereoscopic images can be made with binocular (twin-lens) cameras or single-lens cameras with two separate images made for the left and right views. Anyone can make them, even without special equipment and I’ll be explaining how in this blog. The Victorians began making stereo-daguerreotypes with single-lens cameras but even before photography they drew diagrams, they really were amazingly inventive.

THE INVENTION OF STEREOSCOPY

CharlesWheatstone
Sir Charles Wheatstone – Inventor of Stereoscopy

History lesson time – I can’t mention what stereoscopy is without mentioning the inventor of the stereoscope and hero of stereoscopy, Sir Charles Wheatstone (1802-1875). He was born in England over two centuries ago and invented the stereoscope in the early 1830s before presenting it to the world in 1838. So 3-D was actually invented in the Victorian era even before photography, have a think about that next time you’re chewing popcorn at the cinema with a character popping out of the screen at you, incredible!

Wheatstone stereoscope
Wheatstone’s Original 1838 Stereoscope, King’s College, London.

Wheatstone’s original stereoscope used angled mirrors, one for each eye, and two separate images either side, near your ears. This wasn’t the most convenient method and several years later, in 1849, the Scottish and grumpy Sir David Brewster (1781-1868) designed a lenticular stereoscope which used lenses instead of mirrors, which meant stereoviews could be made much smaller as the two images were side-by-side for viewing.

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A Brewster-Style Stereoscope

This sparked the craze for stereoscopy and caused the mass production of stereoviews in the Victorian-era, many of which you can still find today. If you read most books about stereoscopy they introduce Sir David Brewster as the inventor of the lenticular stereoscope because they quote announcements from the press at the time …written by Sir David Brewster.

DavidBrewster
Sir David Brewster – Angry Scot

A small lenticular and prismatic stereoscope sitting unassumingly in a display case at King’s College, London strongly suggests his announcements may have been porkies. This prototype by Charles Wheatstone was rediscovered in the Science Museum storage rooms by Denis Pellerin and Dr. Brian May from the London Stereoscopic Company in 2018 and announced at King’s College later that year. So even today new facts are being unearthed and others rediscovered about the history of stereoscopy and that’s partly why I find it so exciting, there is always something new to discover.

WheatstoneDisplay
The Wheatstone Stereoscope Display, King’s College, London

MAKING YOUR OWN 3-D IMAGES

You can also make your own stereoscopic 3-D images and you don’t need lots of expensive equipment either, the easiest way is with your smartphone which I’ve made a tutorial about here.

I have written more than I intended to (but I always get carried away with stereoscopy) and yet there is so much more that can be said. Congratulations if you have made it all the way through, you deserve a medal.

Thank you for reading,

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