Stereo photographs on computer monitors are normally viewed by slightly crossing the eyes until the two halves lock together to form one stereo image in the centre. If you find this difficult at first, here is a hint on how to go about it.

Hold your thumb in front of your face about four inches (10 cm) from the tip of your nose. Look at your thumb, but direct your attention over it toward the stereo picture on the monitor. It will be out of focus, but the two halves will be nearly overlapped. Adjust the distance of your thumb nearer or farther until you get the stereo picture to lock into one central image.

Your problem now is to focus on the monitor without uncrossing your eyes. This is easy for some people, difficult for others. Just remember that eye muscles are like other muscles; you have to train them and, perhaps, strengthen them. Practicing the above exercize will do this. Think of learning this as a kind of aerobics for eyeballs. (Can you do three?)

While your eye muscles may get tired quickly and your eyes water from the strain, you will not harm your eyes viewing stereo pictures. Just don't overdo it until you become comfortable with it. Build up your muscles a little at a time and holding your eyes in the crossed position will soon become natural for you.

Stereo viewing assumes that you have two functioning eyes with similar properties or optical corrections. I have heard that between 5 and 10 percent of people are unable to merge stereo images, but most I have known have been able to learn it quite easily. If you need more help, drop me an email message.