Click on photo to see how a digital video scaler can render Star Wars in full super-widescreen glory.
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The latest home theater trend is 2.35:1 constant-height display systems (provided, of course, that you ignore 1080p, 250,000:1 contrast ratios, HDMI 1.3a, Deep Color, DTS-HD Master Audio, Dolby TrueHD, Blu-ray Disc, HD DVD, multi-terabyte media servers, and PS3). While these systems are by no means a brand-new technology, they've recently become an extremely popular addition to high-end home theaters.
Constant-height display systems adjust a front-projected image so that no resolution is wasted on creating black bars above and below the picture when showing super-widescreen movies. For instance, when you go from watching an HDTV program with a 16:9 aspect ratio to a movie with a 2.35:1 ratio, the system fills the entire screen instead of adding bars to compensate for the wider image. To do this, it has to maintain a constant image height — and thus, its somewhat unwieldy name.
The Numbers Game
Before I get around to explaining how the manufacturers pull off this trick, a quick review of aspect ratios is probably in order.
Someone from the National Information Standards Organization once said, "The wonderful thing about standards is that there are so many to choose from." How true. While this was originally a joke from the IT world, it would seem to apply to the A/V world as well, since more than 19 different aspect ratios are used in video and film. Thankfully, I'll be discussing only the few ratios that are most relevant to today's home theaters setups.
An aspect ratio is a simplified way of expressing an image's format, with the width divided by the height. The resulting ratio is often expressed with the height given as a constant of 1. For instance, 2.35:1 tells you that for every inch of height, the image will be 2.35 inches wide. So a 100-inch-tall screen would be 235 inches wide. (While a screen of that size would be way too big for most home theaters, it does provide a pretty simple example of how the ratios work.) Common movie ratios are 2.35:1, 1.85:1, and 1.37:1. Meanwhile, it has become common to refer to the ratios for standard-definition and high-def TV as 4:3 and 16:9, respectively. (The 4:3 ratio equals 1.33:1, while 16:9 equals 1.78:1.) So if we have a 100-inch-tall screen in a 4:3 (1.33:1) format, it will be 133 inches wide. In 16:9 (1.78:1), it will be 178 inches wide.
As if all that isn't confusing enough, the 2.35:1 ratio isn't entirely accurate — at least, not in the way it's commonly used today. A lot of the movies that people refer to as being 2.35:1 are actually shot in 1.85:1 or 2.39:1. Also, 2.39:1 is commonly rounded up to 2.40:1 (as in ads for Runco and Stewart Filmscreen). Early CinemaScope movies and pre-1970 Panavision movies actually were shot in 2.35:1, but the ratio has since become shorthand for anything done in super-widescreen. (Today, CinemaScope and Panavision both use 2.39:1.)
Going Wide
At this year's CEDIA Expo, there were so many booths showing 2.35:1 constant-height display systems that I lost count. Runco's CineWide projectors coupled with Stewart Filmscreen's CineCurve screens continue to generate the biggest buzz. Several other projector manufacturers, including Sim2 and Optoma, announced that they're introducing models with a 2.35:1 lens kit option.
One product that got a lot of attention was Panamorph's UH380 lens system, designed to be used with almost any standard 16:9 widescreen projector. At $2,995, it gives those of us with limited funds a way to get into the 2.35:1 club without having to buy a new projector.
