The stereo effect is created by taking two pictures at once from both the lenses. Thus, simulating the human eye. (The distance between both lenses and both eyes are the same).
In the 1950's again, the stereo cameras were very popular.

Le VERASCOPE,  J. RICHARD, FRANCE, 1894-1900
A very popular stereo-camera of that era- manufactured untill the 30's

Le GLYPHOSCOPE,  J. RICHARD, FRANCE, c1905
Simple bakelite version (compared to the Verascope)

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EHO STEREO BOX,   GERMANY,  1930'S
A box with 2 lenses...simple yet effective!

REALIST, WHITE, USA 1950's
The most popular camera of the 1950s!

ILOCA STEREO model II, GERMANY 1951
A beauty!

TRI-VISION,  HANEEL, USA  c1953

3-D CORONET, UK  1950's

VIEWMASTER personal STEREO CAMERA,  USA  c1952

REVERE STEREO 33, USA 1951-

KODAK STEREO,  USA  1954-1959

TDC  COLORIST,  GERMANY,   1954-60

SPUTNIK,  GOMZ,   RUSSIA,  1960s

STEREO SMENA   RUSSIA,  1970-80s
Handmade sterEo camera made from 2 Smena cameras

NISHIKA,  CHINA   1980s   &  NIMSLO, JAPAN
Interesting quadro-lens  3-D cameras  (novelty?)
while processed on a multi-layer print. it can be viewed in 3-D without any special glasses

3D MODERN CAMERAS,  1990s   USA, CHINA
A try to revive the 3D era with 3D cameras (disposable well as re-usable ones)

Click here to view early  STEREO-VIEWS of PALESTINE