Categories: Blogs & Little Things

JJ’s Now-and-Then Blog – How to Prevent Headaches When Watching 3-D Movies

Many consumers complain that watching 3-D movies gives them eye strain and/or a headache. The explanation, and the solution, are at hand.

When you sit in your chair to watch a 3-D movie at a commercial theater or in your home theater, it is critical that you keep your head (eyes) horizontal (parallel to the plane of the screen, i.e., the plane of the horizon). You can move your head upward or downward, or from side to side, but you cannot tilt your head. The reason for this is shown in the diagram below.

The diagram shows the head of the viewer, looking at the screen. Although virtually all movies are now using polarized glasses to render the 3-D image, I have used a red/green pairing of the two images that create 3-D for convenience.

The 3-D image pair is arranged horizontally (parallel) on the screen. This is why you must hold your head horizontally (parallel to the plane of the screen) as well. The brain sees the two images as they would be seen in a real situation.

If you tilt your head in a real situation, your eyes are tilted, and you see the 3-D pair of images from the live scenery in a tilted plane as well. The brain then sees the two images appropriately. However, in the theater, if you tilt your head, your eyes are seeing the images that are horizontal on the screen. This is not the normal view that your eyes are expecting to see. So, the muscles of your eyes strain to correct what they are seeing, and you get a headache.

My daughter had complained that she didn’t like 3-D movies because she got headaches. So, on Fathers’ Day, we went to see Jurassic World in 3-D. I explained to her the procedure to view the movie. Result: no headache.

So, if you have stayed away from 3-D movies because of this problem, you can now go and enjoy them without concern of post 3-D movie pain. Note that you should use your normal glasses with the 3-D glasses, as the 3-D glasses don’t correct for whatever vision problems you have, such as astigmatism. If you have other vision problems, of course, this procedure may not be of use.

John E. Johnson, Jr.

Editor

John E. Johnson, Jr.

Editor-in-Chief Emeritus. John E. Johnson, Jr. founded Secrets of Home Theater and High Fidelity in 1994, shortly after publishing a hardcopy book of the same title. He served as Editor-in-Chief of Secrets of Home Theater and High Fidelity until 2022. John has been involved in audio and video for more than 50 years, having built radio transmitters, amplifiers, turntables, and speakers from scratch. He was also one of the founders of the Northern California Audio Video Association, now The Bay Area Audio Society. John holds four university degrees, including a Ph.D. in Neuroscience, and has published numerous scientific books, along with dozens of scientific articles on biomedical research topics as well as imaging technology. He was the founder and Editor-in-Chief of two medical/scientific journals for 20 years. John holds several patents, including one on high resolution image analysis and one on a surgical instrument. He has been affiliated with NASA, The National Institutes of Health, The Johns Hopkins University, Stanford Research Institute, and The University of California at Berkeley. He is President of the consulting firm Scientific Design and Information, Inc., which is based in Redwood City, California. John resides in the San Francisco Bay area with his wife and multiple kitties! His daughter, Cynthia, who was an integral part of SECRETS for many years, resides in San Francisco.