3D movies are a projection trick that can be manipulated. Essentially, the 3D designer (Stereographer) is using the cameras that capture the 3D and expanding or reducing the distance between them. It’s like if you could push your eyes closer together it would make everything seem bigger and separating them more would make you feel like a giant.
What is 3D? It is a motion picture that enhances the illusion and brings you to the reality of the screen. In the late ’80s or ’90s, watching movies was just like watching on an ordinary screen but bigger.
The advantage of watching 3D movies is, there is the potential to take audiences into reality on the screen. 3D undoubtedly makes what we are seeing more vivid and, dare I say it, we can almost touch the world the characters exist in the story.
The disadvantage of 3D is some people who watched 3D movies experienced motion sickness during watching a movie. It is yet to be determined if it’s the 3D itself or the glasses. Because some people experience headaches, others feel that they are dizzy and sick. The glasses are another argument against 3D movies. People say they can be uncomfortable and distracting.
Furthermore, nowadays all movie houses offer plastic specs at an extra cost. The other disadvantage of watching 3D movies is, 3D is an exciting experience on the big screens, but what about when we watch these movies at home it lessens the exciting experience and thrill.
In the 2D movie you are just watching on a large screen and with surround sounds. Therefore, there is nothing new, no effects, no visual effects unlike in 3D when you wear your 3D glass.
How 3D Movies Function
First, if the lens of the camera was always the same field of view as human vision (arguably 50mm) we could separate the left and right cameras to match the distance between our eyes. Thereafter, we can fairly accurately recreate natural depth. This is called orthostereoscopy. When 3D first began in the late 1800s (very shortly after 2D photography), this is how it was done.
Alas, lenses are very rarely 50mm and can vary greatly from shot to shot. Not to mention that the 50mm standard is no longer the best match if the camera’s sensor size changes. Thus, it becomes a very complex formula to always match the human vision.
Last Things (3D Movies)
Most 3D these days is a post-conversion process which is not necessarily representative of physical space. 3D is built somewhat abstractly “by eye” at the hands of 3D artists. The result can be exciting and captivating, though not look like you would naturally see it.
The size of the screen and your distance from it varies from seat to seat across the planet. Hence, the ratio and formula would need to be designed for each viewer (which is impossible) to match exactly to human vision. This is one reason VR can be so captivating. Its ratio is the same for everyone.
A 3D movie has two versions of every frame, each from a slightly different angle. With this, it mimics the way we see the world through our two eyes.
3D movies tend to be darker (this doesn’t have to be the case, but often is) and the way you have to refocus your eyes to see faraway objects in 3D can give people headaches.