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2D glasses work by having the same direction polarisation lens in both eyes, letting people who normally get headaches from 3D films, watch 3D glasses with friends (obviously, if they're on their own they can just go watch 2D movies)

However on the purchase page they say:

Note: 2D glasses work in 3D cinemas. However, they do not work at IMAX theatres.

Why is that? What makes IMAX cinema 3D different?

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The most common form of 3D projection (apart from IMAX 3D) is RealD, and this uses circular polarisation. However IMAX 3D uses linear polarisation. This means RealD glasses won't work in an IMAX and vice versa.

The 2D glasses are made by aligning the polarising lenses to be the same on both sides so that both eyes receive the same image. This technique works for both RealD and IMAX, but just as for the 3D glasses you need circularly polarised glasses for RealD and linear for IMAX.

I assume the glasses in your link have been made with circular polarisers so they work for RealD but not for IMAX.

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  • $\begingroup$ This begs the question (perhaps not appropriate/on-topic here) why do they differ on their polarisation methods/types? $\endgroup$ – Pureferret Aug 5 '16 at 15:25
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    $\begingroup$ @Pureferret: Apparently linear polarisation is brighter but more prone to distortion if you move your head. Choosing linear over circular is just a matter of which trade-offs you prefer. I speak as a Googler not an expert in film technology! $\endgroup$ – John Rennie Aug 5 '16 at 15:27
  • $\begingroup$ I've experienced the distortion myself! Thanks fort the heads up. $\endgroup$ – Pureferret Aug 5 '16 at 17:40

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