davecobb | Feb. 7th, 2009

A brief consumer-awareness message (and personal opinion piece) for those of you who enjoy 3D movies.

While 3D movies are filmed or produced in the same basic way, they can be projected in numerous ways. Currently, there are two main "flavors" of 3D delivery at your local theaters -- one system is called "RealD" (also re-branded as "Disney Digital 3D", but it's the same thing) and the other is called "Dolby3D". Both work in different but effective ways to take two discreet left-and-right images on the screen and decode them into each eye for your brain to put back together again -- and both do a very good job of that, with little to no "ghosting" of the images or cross-pollution of each image, like in past 3D techniques. Both are capable of an astounding, clear 3D image.

The difference is, the glasses. RealD uses a flat, plastic polarized lens, while Dolby3D uses curved glass lenses with special color-spectrum filter grading applied to them. You'd think, upon first glance, that glass would inherently offer better optics than plastic -- and that the Dolby name gives it the leg up in terms of cinema technology. However, after having seen hundreds of 3D films and literally dozens of 3D tech demos and installations over the years, I find the Dolby system to have a teensy, tiny flaw that gets in the way of a perfect 3D image.

Have you ever worn a pair of eyeglasses, prescription or sunglasses, and seen your own face reflected in the curve of the inside of the lens? That's what happens with the Dolby glasses. They have a distinct curve, and are highly reflective, specially-coated glass -- so in a darkened theater, with the bright projection screen illuminating your face, you end up seeing your cheeks (and sometimes even your own eyes) reflected in the lens before you. Your eye naturally wants to focus past it, on the screen -- but it ends up being an annoying "haze" or "halo" around the otherwise clear and sharp screen image.

The RealD glasses are flat, and don't have the same convex qualities -- and since they're just plastic polarization filters, aren't nearly as reflective. Your eye focuses right past them, and no light is bounced back from your face.

I've actually written to the Dolby folks about this -- they know it's a problem, and the first step they took is to make the ear stems on the glasses very "thick" (like goggles) to block the light from getting behind the lenses. But it doesn't completely resolve the issue, and they are looking into additional anti-glare coatings and such to try and eliminate the "haze" problem.

Unfortunately, many high-end theaters (like the ArcLight here in Los Angeles) are defaulting to the Dolby system because it "feels" more expensive or "better" because of the glass lenses (RealD is available at most AMC theater chains). Either way, both systems are cutting-edge and do offer astounding 3D -- I've just found that, in direct comparison, the Dolby3D system still needs a bit of tweaking IMHO. Your mileage may vary, so do your homework when going out to see Coraline this weekend -- you can search for theaters and what system they're using via the links above.