- The International Stereoscopic Union is the only international stereo club in the world. The ISU is a club of individual 3-D enthusiasts as well as a club of stereo clubs. The ISU's members currently number 900 and come from 32 countries world-wide. Although the ISU caters mainly to the 3-D amateur photographer, the ISU also has much to offer members who are professional stereo photographers as ...www.stereoscopy.com/isu