# Why am I always having problems with 3D movies? **URL:** \ **Category:** Factual Questions\ **Created:** [April 5, 2009, 6:04am UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039 "2009-04-05T06:04:43Z")\ **Posts on this page:** 7\ **Page:** 3
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [April 25, 2009, 3:14pm UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039/41 "2009-04-25T15:14:44Z")
Ghosting can be caused by a number of things: the film itself, the glasses, the filters on the projector, and even where you’re sitting in the theater. If I had to guess, I might say that the polarizing filters in the Chicago theater are older and have faded a bit, and should be replaced. I’m glad you gave 3D another chance. It’s not all bad. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [April 25, 2009, 3:46pm UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039/42 "2009-04-25T15:46:26Z")
If stereoblind people see ghosting when watching a 3d movie, why don’t they see ghosting when looking at actual objects in space as well? - ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [April 25, 2009, 4:05pm UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039/43 "2009-04-25T16:05:36Z")
Ghosting is an artifact of 3D displays. Both left and right images are projected on the screen at the same time. To create the illusion of 3D, each of the viewer’s eyes should see only the image intended for it. This is accomplished by using filters of some kind: the filter on the left eye blocks the right eye image and vice versa. In practice, the filters aren’t perfect, and some portion of each image can leak through the filters into the other. With linear polarizers, this can happen just by tilting your head a little. It’s also more prominent in dark scenes with high contrast. So you can see that, since two images are always being projected, ghosting can happen to either eye or both eyes. So someone with vision in only one eye would still see ghosting in any less-than-ideal 3D presentation. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [April 25, 2009, 4:44pm UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039/44 "2009-04-25T16:44:11Z")
Is the implication that there is a bit of ghosting for everyone, but that stereoblind people notice it more? ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [April 25, 2009, 5:15pm UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039/45 "2009-04-25T17:15:42Z")
Only in the sense that since they can’t see the 3D, stereoblind people may notice artifacts that the rest of us aren’t paying attention to. But if the ghosting is particularly bad, or if you know what to look for, it is just as visible to people with perfect vision as to those who have problems with stereo. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [April 25, 2009, 5:52pm UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039/46 "2009-04-25T17:52:12Z")
> [@commasense](#): > > Only in the sense that since they can’t see the 3D, stereoblind people may notice artifacts that the rest of us aren’t paying attention to. Yep, that’s what I was saying. It all makes sense to me now, thanks! -Kris ---
**Author:** ![Alex\_Dubinsky](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Dubinsky](https://boards.straightdope.com/u/Alex_Dubinsky)\ **Post date:** [April 25, 2009, 11:22pm UTC](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039/47 "2009-04-25T23:22:24Z")
> [@Frylock](#): > > Is the implication that there is a bit of ghosting for everyone, but that stereoblind people notice it more? No, ghosting and stereoblindness are totally different. Ghosting is when you converge the images successfully, but the filter technology sucks and each eye sees two image. With ghosting, you’re seeing four images total. Quote-unquote stereoblindness is when you can’t converge the images, usually because the divergence is more than you’re comfortable with. (Big divergence makes the 3D pop out more, but requires more practice.) [Previous page](https://boards.straightdope.com/t/why-am-i-always-having-problems-with-3d-movies/492039.md?page=2)