One big promise of passive 3D is that you can wear lightweight, inexpensive polarized glasses like the ones you get in movie theaters, rather than the bulkier, more expensive active-shutter glasses required by current 3D sets.
The first passive 3D TV to hit the market is Vizio's 65-inch VT3D650SV ($3,700), a 1080p LCD TV that uses an edge LED backlight. Testers from Consumer Reports (CR) bought a set as soon as it was available and recently completed preliminary testing in its TV labs.
For purposes of comparison, CR pitted the new Vizio set against Panasonic's top-rated TC-P65VT25 ($4,300) plasma 3D TV. The magazine says it has found plasma to be a better technology for 3D, primarily due to the lack of ghosting, so testers were curious to see how the Vizio passive set stacked up.
A lot to like
In general, there is a lot to like about the VT3D650SV. For one thing, the polarized glasses are very comfortable to wear; they weigh just 0.7 ounces, so they felt very similar to wearing regular sunglasses. CR also liked that you get four pairs of glasses with the TV -- with additional pairs expected to cost from $10 to $30. That's a far cry from the $130 to $150 you have to shell out for active glasses.
In addition, the passive 3D glasses dim the image less than any of the active-shutter glasses testers have tried, enabling the Vizio to produce the most satisfyingly bright picture we've experienced when viewing 3D.
Perhaps even more important, CR found that ghosting -- which has been a significant distraction on almost all the 3D LCD TVs it's reviewed -- is reduced to the point where it gives plasma TVs a run for their money. The testers note that when they watched both Avatar and Monsters vs. Aliens in 3D, "we were wowed by the effortless presentation of clean 3D without any of our usual ghosting complaints." Other passive advantages, they say, include virtually no flicker, and the lack of any issues related to the glasses syncing properly to the TV.
But Consumer Reports' initial excitement about the Vizio was tempered by what it says is "the most significant downside to the passive 3D technology: the noticeable loss of resolution that's the result of the way the separate 3D images are displayed for each eye."
Passive TVs use a different 3D technology than the current active 3D sets already on the market. Unlike those sets, which use active glasses with shutters that open and close very rapidly to provide each eye its own view, passive TVs use a polarizing film on the TV screen itself, which divides the picture into alternating lines, much like the interlaced images on older tube TVs. Each lens in the glasses blocks the images meant for the other eye.
As a result, each eye receives only half the vertical resolution of the image. So while active sets can send full HD 1080p (1920x1080) signals to each eye when connected to a high-def 3D source, such as a 3D Blu-ray player, the best a passive 3D TV can do is 1920x540. And if you get your 3D signals via cable or satellite broadcasts, which squeeze 3D signals into the space meant for a single high-def image, cutting the horizontal resolution, the resolution is reduced even further, to 960x540.
This loss of resolution may be visually subtle to some viewers, depending on the 3D program material, but it's likely to be noticeable -- and bothersome -- to more discerning viewers.
In CR's preliminary tests, this loss of resolution resulted in interlaced-like image effects, such as jaggies and moiré, which recall the 480i- and even 1080i TVs of not too long ago. For example, overall picture detail was much courser on the Vizio than with the Panasonic, and there was visible blurring on objects in motion in some scenes.
In addition, there were jaggies on the edges of objects, especially on diagonal lines. For example, in the opening credits of Monsters vs. Aliens, the DreamWorks logo features a boy with a fishing pole sitting on the moon. On the Vizio, the fishing pole looked like a dotted line; with the Panasonic the pole was a complete, unbroken line.
While the artifacts weren't terrible, they did feel like a throwback to an era before progressive-scan images were available -- one the testers say they were happy to leave behind. When comparing a detailed, 1080p 3D "freeze frame" Blu-ray image on the Vizio and Panasonic sets, the difference is quite apparent. Depending on the scene, the Vizio often exhibited significant jaggies and moiré; images on the Panasonic were detailed, smooth, and filmlike, free of classic video artifacts.
There were also a few other issues, likely attributable more to the differences in display technology than to 3D. For example, there was "clouding" in the corners and sides of the Vizio sets on dark scenes, caused by backlight uniformity issues, and the viewing angle was noticeably narrower. That said, the testers believe the new Vizio set's advantages allow it to deliver the best overall 3D performance available of any LCD 3D TV they've tested.
Here's the bottom line on the Vizio VT3D650SV "passive" 3D TV:
- Provides a high-quality, comfortable 3D viewing experience;
- Minimal ghosting, comparable with the best plasmas;
- Very comfortable, lightweight, low-cost polarized glasses;
- Bright 3D image.
- Vertical resolution cut in half (from 1080 to 540 lines);
- Visible video artifacts, such as jaggies and moiré, in some scenes;
- Very fine details that fall within a row of pixels tend to "shimmer" since each eye is only getting half the image;
- 3D broadcasts transmitted in "side-by-side" mode displayed on the Vizio will have a resolution of 960x540, one-quarter that of full 1080p;
- Unlike prior Vizio models with wide viewing angles, this one has a more limited viewing angle, comparable to that of most LCDs.