Just when everyone has gotten used to the concept of converting from plain ole 4:3 television to widescreen 16:9 video systems, a new format option is popping up-some people are going with even wider screen formats for their home theaters. The most popular of the alternative formats is 2.35:1 since many motion pictures are filmed in this aspect ratio. If you are about to install a new home theater, a fundamental question to ask would be, "Is the 2.35 format right for me, or should I stay with 16:9?" Let's examine the issues and see what's right for you.

What is 2.35 Widescreen?

First, let's be clear about what we are talking about. The idea is to install a screen with a 2.35:1 aspect ratio, or 2.35 units wide for every one unit of height. The big advantage is that you can see movies that are made in this format full frame, without any black bars above or below the picture. As an example, The Fifth Element was done in 2.35, and if you project it onto a 2.35 screen it would look like this:

Meanwhile, all regular HDTV programming is in 16:9 format, otherwise known as 1.78 because 16 divided by 9 is 1.78. In addition, there are a few films done in 1.78, and many more are done in 1.85, which is so close to 1.78 that you usually don't notice the difference. When this type of material is displayed on a 2.35 screen, you get black vertical bars, or columns, on each side the image, commonly referred to as pillar-boxing. For example, the movie Chicago was done in 1.85. Here is what a scene from Chicago looks like on a 2.35 format screen:

There is also plenty of 4:3 format material still being watched today as well. It can be positioned in the center of the 2.35 screen, with larger pillar-boxing on either side. The following is a scene from Gone With The Wind, which was done in 4:3, on a 2.35 screen:

The Aesthetic Appeal of 2.35

The reason some people like the 2.35 format is that it can have a more dramatic appearance compared to standard 16:9 widescreen. If standard 16:9 is being displayed, and suddenly the curtains retract revealing a wider screen, and then a 2.35 format movie appears on that screen, it looks even bigger and more impressive than the conventional 16:9 image. There is a certain WOW factor involved with this, and many people find that it adds excitement to the home theater experience.

In addition, many people think that 2.35 films are the most important and/or most common type of video material they watch. So they want to see them full frame, without black bars above and below the image, which is what you get if you display them on a 16:9 screen.

The Aesthetic Downside to 2.35

In general, the most significant penalty to be paid by going with a 2.35 set up is that your 16:9 and 4:3 images will be much smaller than they would be if you used a 16:9 screen. Why? In the vast majority of home theater situations, the room dimensions place a practical limit on the maximum width of the screen before placing any limitation on its height. Let's assume for example that the wall you are projecting onto is 14 feet wide and 9 feet high. Let's also assume you want to leave two feet to either side of the screen for speaker placement and aesthetic clearance from the walls. Practically speaking, this wall size limits you to a maximum screen width of about 10 feet.

Now, since this room has a 9 foot ceiling, the height of your screen can be pretty much anything you want. If you go with a 2.35 screen, it will be 10 feet wide and 4.25 feet high. If you opt for a 16:9 screen, it will be 10 feet wide and 5.62 feet high. And if you wanted to go 4:3, it would be 10 feet wide and 7.5 feet tall. Since this room size does not limit the height of the screen, the 2.35 format actually turns out to be the smallest screen you can install from a total square footage perspective.

Now, on this ten-foot wide 2.35 format screen, every image you project will be the same height, which is 4.25 feet. What will vary is the width of the image. A film in 2.35 will take up the entire 10 foot screen width, but a 16:9 image will be only 7.56 feet wide. The total square footage of that 16:9 image will be 4.25 x 7.56 = 32.1 sq. ft. Conversely, if you installed a 16:9 screen that was 10 feet wide, the total square footage of your 16:9 image would be 10 x 5.62, or 56.2 square feet. That is a much bigger 16:9 image-almost double the square footage. To illustrate, compare the following images of the 1.85 format scene from Chicago on a 2.35 screen, and on a 16:9 screen of the same width:

The same is true of 4:3 material. On a 10-foot wide 2.35 screen, a 4:3 picture will be 24 square feet. On a 10-foot wide 16:9 screen, a 4:3 image will be 42 square feet-again, almost double the size in terms of total screen area.

Meanwhile, whether you use a 10-foot wide 2.35 or 16:9 screen, a 2.35 film will be the same size either way-10 feet wide and 4.25 feet tall for a total of 42.5 square feet no matter what. The only difference is that the 2.35 screen gives you a full frame effect, and the 16:9 screen gives you black bars top and bottom.

Therefore, once you determine how wide a screen you can install, that defines the size of your 2.35 image. Your only question is how big do you want your 16:9 and 4:3 material to appear? If you want those images to be smaller than your 2.35 films, go with a 2.35 screen. If you want them to be larger than your 2.35 films, go with the 16:9 format.

Or if you want your 4:3 image to be really huge, you can go with a 4:3 screen. We have a 150" diagonal Stewart Studiotek 130 in 4:3 format. That is 10 feet wide by 7.5 feet tall, for a commanding 75 square foot picture. I just watched the new HD DVD edition of Casablanca on it the other night using the Canon Realis SX60. For some of us, that is a dramatic home theater experience. Given my personal enjoyment of old classic 4:3 films, I would not trade the grandeur of a 150" diagonal 4:3 image for the small picture I'd get on a 2.35 screen, just to make 2.35 films appear larger in comparison. But there is nothing right or wrong about this, it is just personal preference.

The bottom line is this: you are the director in your home theater. You can decide how you want various format images to be screened. Some people love that feeling of the screen opening super wide for 2.35, and would prefer to limit the size of 16:9 and 4:3 material in order to make the 2.35 films look larger. Some prefer to take advantage of a taller screen that allows a larger presentation of 16:9 and 4:3 images. The only relevant question is--how do you want to set up your own theater?

If you go with 2.35, how do you do it?

In theory, if you want to install a 2.35 aspect ratio screen, the ideal match would be a native 2.35 format video projector. However, there is no such thing on the market, at least at the moment. Almost all video projectors made for home theater use are 16:9, with the exception of a very few that are 4:3. So you will need to use a 16:9 projector. The question is, how do you fill a 2.35 screen with a 16:9 projector?

There are two ways to do this. The first, easiest, and least costly way would be to select a projector with a powered zoom lens and powered vertical lens shift. When viewing a 2.35 film, you zoom the lens to a wide angle setting such that the image perfectly fits the screen. Then when you switch to either 16:9 or 4:3 material, you use the powered lens to zoom forward until the image shrinks to the point that it fits the frame. If the projector is ceiling mounted and projecting at a downward angle, you may also need to use the vertical lens shift to realign the center of the image with the center of the screen. But with these two adjustments, you can easily achieve the objective of centering smaller 16:9 and 4:3 images in the middle of your 2.35 screen.

The other way to manage this process is with the use of an external anamorphic lens that is placed in front of your projector's lens. An anamorphic lens is designed to distort an image by either stretching it horizontally or compressing it vertically. (Lenses which stretch horizontally are called Horizontal Expansion lenses, or HE. Vertical Compression lenses are designated VC.) In this case, you want to maintain a constant image height that fits your 2.35 screen no matter what type of video material you are viewing. So you need a Horizontal Expansion lens. There are several on the market, but one of the most popular is the Panamorph UH380, shown here along with its optional M380 motorized track in front of a Panasonic AE900 projector:

The key to the use of an anamorphic lens is that it be deployed when 2.35 material is being displayed, and it must be removed when you want to see 16:9 or 4:3. So your options are to either put it on a motorized track as illustrated above, or put it on a manual track so you can slide it back and forth by hand. If you are ceiling mounting the projector, the motorized track is, practically speaking, almost mandatory. If you place the projector on a rear shelf that is within easy reach, the manual track becomes a more workable (and much less expensive) solution. (Panamorph's UH380 lens is $2,495, and their optional M380 track is another $2,495, which brings it up to about $5,000 for the total package. However, you can build a simple manual device using a sliding door track from Home Depot for under $20.)

In a fully automated system, you can have motorized drapes or screen masks that will automatically open or close to accommodate the image size on the screen. These systems are complex and expensive, but custom home theater installers are trained to wire it all together if your budget allows you to get this extravagant.

Vertical video rescaling a vital step

As note above, the anamorphic lens optically stretches the image horizontally. In order for this to work the projector needs to be able to distort the image in an equal and opposite manner, so it comes out looking normal on the screen. Many projectors have a rescaling option to accomplish this. On the projector's display, the 2.35 picture will be stretched vertically to use the entire height of the 16:9 format. In this mode, if the anamorphic lens is not in place, you would see the 2.35 picture stretched vertically to fill a 16:9 screen so that objects and people look excessively tall and skinny. As you slide the anamorphic lens into place, the image maintains its height, but stretches out horizontally to fill the entire width of the 2.35 screen and everything looks normal once again.

If your projector does not have the rescaling option to distort a 2.35 image vertically, you must either acquire a projector that does, or get an external video processor that will perform this task. And it must rescale all signal types you plan to use. Some projectors may rescale 480i, but not 720p or 1080i. Some may rescale component video but not HDMI. Test your projector's aspect ratio options on every signal type before making the leap to a 2.35 screen and an anamorphic lens.

Other factors to keep in mind

Not all anamorphic lenses are compatible with all projectors. The larger the onboard lens on the projector, the larger the anamorphic lens must be to accommodate it. Check the lens vendors for compatibility with your particular projector model before buying.

Also, anamorphic lenses are designed to produce optimally sharp images at certain "sweet spot" throw distances. For example, the Panamorph UH380 above delivers its sharpest picture at a throw distance of 16 feet. If you try to set it up for a shorter or longer throw distance, the picture will lose some of its sharpness. Make sure to determine the optimal throw distance for the anamorphic lens you select, and verify that your room dimensions will accommodate it.

What is the advantage of the anamorphic lens?

Advocates of the 2.35 concept often point to three advantages to be gained from the use of an anamorphic lens. First, in theory it allows you to use the full light output of the projector. When a 16:9 projector is displaying a 2.35 film in its normal aspect ratio, it does so by placing black bars above and below the image. Those black bars amount to about 25% of the total picture area, which means that 25% of the potential light output of the projector is being blocked. By stretching the 2.35 image vertically to take the full height of the display, the black bars are eliminated and the total light output of the unit is being used. The anamorphic lens then brings that total light output into use by stretching it across the 2.35 screen.

This argument does not take into account the optical properties of the projector's zoom lens. Let's suppose that instead of using the anamorphic lens, you simply use the projector's zoom features to increase the size of the 2.35 image to fill the screen. To do that you would be moving the lens to a wider angle setting than it would be if the anamorphic lens was in use. This always allows the lens to transmit more light. So depending on the projector, some or all of that 25% light lost to the black bars is compensated for by opening the zoom lens to a wider angle setting. (This observation does not apply if you are at the extreme ends of the zoom range, but if you are indeed at the extreme ends of the projector's zoom range you are most likely out of the sweet spot of the anamorphic lens as well).

A second and more genuine advantage of the anamorphic lens is that it allows the use of 100% of the pixels on the projector's display. If you have a 1280x720 format projector, and you use the vertical stretch plus the anamorphic lens to produce your 2.35 picture, you use all 1280x720 = 921,600 pixels to create the image. If you instead use the zoom lens adjustment to blow up the picture, you end up using about 75% of that, or a bit under 700,000 pixels. So the anamorphic lens can reduce visible pixelation in the image by using more pixels.

But the third and most potent argument for the use of the anamorphic lens is that it produces a home theater experience that is quite different than the standard widescreen presentation. By setting up your system this way, you designate 2.35 films to be the most important of the material to be viewed. When you choose to display 2.35 larger and wider than either 16:9 or 4:3, you cause it to have a greater visual and emotional impact. Moreover, when the lens deployment mechanism, the curtains, and the screen masking are all motorized and automatic, the combined effect produces a WOW factor that some regard as the ultimate in home theater.

Other Limitations of Anamorphic Lens

Several limitations to the use of anamorphic lenses have been noted above, but a couple more points should be made. First, they are quite expensive relative to the projectors. The Panamorph UH380 is the least pricey of the HE lenses; others like the Schneider and ISCO are much more expensive. For the price of an anamorphic lens you can step up from a good 720p projector to a high performance 1080p model.

Second, one of the benefits of the new Blu-ray and HD DVD formats is that they will deliver movies in native 1920x1080 format directly to a 1080p projector, so that they can be viewed without scaling. The use of an anamorphic lens requires that 2.35 material encoded in native 1080p format be rescaled vertically, and then stretched optically. So you lose the advantage of seeing the film in its pure native format, perfectly reproduced from the HD DVD or Blu-ray disc. Advocates will say that the cost in reduced image acuity is insignificant, and it may well be. But it is something to be aware of.

Conclusion