Difference between Active 3D and Passive 3D

Passive 3D

Passive 3D glasses

The alternative is passive 3D, as seen on TVs such as the LG 47LM670 and Panasonic Viera TX-L32ET5B. These TVs have a polarising film over the screen, which separates the image into left and right types. The glasses, which are also polarised (like the lightweight type you use in the cinema), filter out the unwanted image and let only the correct image through. 

As you'll see only half of the image in each eye, 3D content won't be shown in full HD 1080p resolution.

Pros: Cheap, lightweight glasses
Cons: Lower resolution images

Active 3D

Active 3D glasses

Active 3D is used on models such as the Sony Bravia KDL-32EX723,Samsung UE55ES8000 and Panasonic Viera TX-P42XT50B. The active 3D glasses that you wear synchronise with the TV via a wireless signal and rapidly blink on and off like a camera shutter, playing back full 1080p images to the right eye and the left eye at a rate of 50 frames per second. This means that picture quality is often better than that of passive 3D.

The glasses need a power source to switch on and off (either a small battery or via a USB charge) and, as a result, are expensive. Some 3D TVs come supplied with a pair (or two) of active 3D glasses, but extra pairs cost from around £40. The glasses will work with that specific brand of TV only.

Pros: Full 1080p image for each eye
Cons: Expensive, clunky glasses