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4:3 vs. 16:9 -- What is the best solution?

Evan Powell, November 21, 2001

Option #1: Native 4:3 Projector with a 16:9 Screen

Currently there are hundreds of 4:3 projectors on the market and only a few 16:9's. So 4:3 projectors currently offer much greater variety in terms of price and performance. Since many native 4:3 projectors will display both 4:3 and 16:9 signals, a lot of people are buying them for home theater.

Most 4:3 projectors are made to address the commercial market, but some are made for both commercial use as well as home theater. Some home theater manufacturers like Runco, Vidikron, DWIN, Marantz, Sim2/Seleco, and Sharp have developed models of 4:3 projectors that they have targeted exclusively to the home theater market.

Since 16:9 format is all the rage these days with HDTV and all, many people have chosen a 4:3 projector, but combined it with a 16:9 format screen. This is one legitimate way to go at the moment. However, it involves compromises that you need to be clear on. Let's consider how this combination displays a 16:9 image first.

When a 4:3 projector displays a 16:9 signal, it will project it by using 75% of its 4:3 displays (either LCD panels, DLP chips, or LCOS chips). So a native 4:3 XGA resolution machine which is 1024 x 768 pixels would use only 575 lines of the total 768 to create the image. The active pixel matrix of 1024 x 575 creates a 16:9 aspect ratio image, and the remaining 193 lines are inactive.

This produces black bars at the top and bottom of the projected image due to the unused lines in the panels or chips. So if you have a 4:3 projector with a 16:9 screen, you set up the projector so that the black bars will fall off the top and bottom of the screen. Voila, the projected image fits your screen format.

Easy enough so far. And if everything you ever wanted to watch was 16:9, you'd be done. Trouble is, there is an enormous amount of 4:3 video material in the world. So how do you get a 4:3 image to fit onto your 16:9 screen?

You have several options. One way is to get a projector that has a power zoom lens with an adequate zoom factor. With this arrangement you can set up the projector so that you use the zoom feature to adjust the picture size.

So for example, the Sanyo XP21N has a powered 1.3x zoom lens, which means you can adjust picture size by up to 30% from one end of the zoom range to the other. Therefore, if you set the zoom to maximum wide angle for displaying 16:9, you can zoom it to the opposite end of its throw range and reduce the picture size by 30%. Since a 4:3 image is 33% narrower than a 16:9, this will put almost all of the 4:3 image in the middle of the screen with just a tiny fraction of the image falling onto the top and bottom screen mask. In order to accomplish this, you must set up the projector at exactly the right distance from the screen to fit both formats, but it is certainly something you can do.

Any native 4:3 projector that has a powered zoom lens with a zoom factor of 1.3x or greater can be set up in this manner. (Actually, you could even use a projector with a manual zoom lens if you table-mount your projector, or if you want to put up with step ladder access to reach your ceiling mounted projector every time you change aspect ratios.) If the projector has a zoom factor of less than 1.3x, you won't be able to get all of the 4:3 image squeezed into the same picture height as your 16:9 image.

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Option One Continued
Contents: Introduction Screen Option One Option One Continued Anamorphic Lenses
  Screen Option Two No Right Solution Screen Option Three Conclusion