The fine points of finding the perfect home theater projector

Experts say home-theater projectors might not be the best type of HDTV for everyone, as they require low light levels for the best image quality, and there are lots of extra costs and requirements compared to LCD TVs and plasma TVs; see the ConsumerSearch reports on those types of HDTVs for more information about them. However, home-theater projectors also offer gigantic screens that are unavailable any other way and a true movie-theater-at-home experience -- including the ability to enjoy the full impact of 3D movies. If you think a home-theater projector is right for you, here are some things to keep in mind as you shop:

  • Figure replacement lamps into long-term cost. All home-theater projectors use replaceable lamps. Average lamp life is between 2,000 and 4,000 hours, and replacement lamps are not cheap. Most cost upward of $250.
  • Experts say the image-quality gap between DLP and LCD projectors has closed. DLP projectors suffer from a phenomenon called the rainbow effect in certain images, but reviewers say it can only be seen by a small percentage of people, and the best projectors use a faster color wheel that minimizes it. LCD projectors are prone to the screen-door effect, which means certain images appear as if they are being watched through a mesh screen. However, that's not much of a concern with modern projectors, and especially with those that offer 1080p resolution. Most budget and some mainstream DLP projectors have little or no zoom range and lens shift, and that can make them harder to place in a room than LCD projectors. Some of the cheapest LCD projectors have some of the same issues and limitations.
  • HD projectors deliver the best home-theater experience. Although home-theater projectors with lower resolutions are available, experts say that the best home-theater experience is obtained with a projector that's capable of displaying a 720p (1,280 pixels by 720 pixels) or 1080p (1,920 pixels by 1,080 pixels) HD image. In addition, some 720p projectors have a native resolution of 1,280 pixels by 768 pixels, which allows them to display full-frame computer XGA signals (1,024 pixels by 768 pixels) at their native resolution without cropping or compression. Projectors with 720p resolution remain significantly less expensive, but prices for 1080p projectors have dropped.
  • Brightness and contrast ratio are important, but take manufacturer specifications with a grain of salt. Measured in ANSI lumens, screen brightness refers to the light thrown out by the projector. Projectors with higher brightness outputs are better able to handle ambient light and allow for bigger image sizes. Contrast ratio refers to the difference between the darkest black and brightest white in a projected image. A high contrast ratio implies -- but doesn't always deliver -- deeper blacks. Differences among manufacturers in the measurement of  the contrast ratio often render that specification meaningless.
  • Adjustable lens shift and a wide throw distance range allow for more installation flexibility. Lens shift refers to the ability to move a lens up or down, or right to left, to center the image on the screen without artifacts such as keystoning, or a wider image at the top or bottom. Throw distance refers to the distance between the screen and the projector to create a desired image size. A fixed-lens projector has a fixed throw distance set by the manufacturer. A zoom lens lets the user change the throw distance to suit the installation, with wider zoom ranges providing the most flexibility. Almost all home-theater projectors have a zoom lens, though in some cases the zoom range might be very short. Many DLP projectors and some budget LCD projectors have limited or no lens-shift adjustment.
  • Consider the size of your room. Most projectors are capable of throwing an image of more than 100 inches, diagonally. That means that most will need to sit at least 10 feet away to get the best view -- although some are now suggesting sitting closer when watching 3D content. In any event, projectors may not be the best choice for a smaller room.
  • You'll get the best image if you buy a projection screen for your projector. A white wall can be used, but you won't get the best image quality and you will lose brightness. Of course, a screen will add to the cost of your home theater system, though some budget options are available. See our report on projection screens for some suggestions.
  • Factor in the cost of a home theater system. Most projectors don't come with an audio system. If yours is among those that don't, you'll need to hook it up to a home theater audio system.
  • Home-theater projectors don't have their own tuners. Because of that, they can't display television signals from an antenna, but they can display HDTV signals from a cable box or satellite receiver.
  • Look for at least one HDMI input, and more are better. HDMI connections are all-digital and are the preferred way to send high-definition signals from one piece of equipment to another. In addition, HDMI is compatible with HDCP (High-Bandwidth Digital Content Protection), a copy-protection scheme incorporated into Blu-ray Disc players and upscaling DVD players. An HDMI input is required to see images from those sources at their highest resolution and picture quality.

Home theater projectors vs. business projectors

While they share many common characteristics, business projectors and home-theater projectors serve very different functions and have very different audiences. For business users, digital projectors have taken the place of the overhead projectors of yesteryear. Mobile professionals hook up a projector to a computer, projecting an image on a large screen or wall for presentations, and many business projectors can play back files stored internally or on a flash drive without the need of a computer. Business-oriented projectors weigh between 1 and 10 pounds, and they usually come with a carrying case and wireless remote control.

Miniature projectors -- called pico projectors -- have also gained popularity. These projectors are small -- some are virtually pocket-sized -- and they typically weigh a pound or less. However their relatively low light output limits screen sizes, making them best for small group or one-on-one presentations. The maximum resolution of business projectors is usually SVGA (800 pixels by 600 pixels) or XGA (1,024 pixels by 768 pixels), although widescreen business projectors with WVGA resolution (854 pixels by 480 pixels) are also available. See our separate report on portable digital projectors for more information on these.

Projector technologies: DLP, LCD and LCoS

When you start shopping for a projector, you'll immediately notice that there are two main projector technologies on the market: digital light processing (DLP) and liquid crystal display (LCD). A third technology, liquid crystal on silicon (LCoS), is also used, but mostly in higher-end projectors.

Historically, DLP projectors boasted better contrast and black levels, while LCD projectors had better color saturation with less fan noise and lower operating temperatures. Because of improvements in both technologies, those differences have almost disappeared.

There are some other significant differences between the two technologies that could make one or the other more suitable for you. For example, LCD projectors still have a brightness advantage, but DLP projectors tend to be a bit smaller because the technology takes up less space.

DLP does have some significant disadvantages. Most notably, they suffer from what is known as the rainbow effect. Because of the way these DLP projectors generate an image, a small percentage of viewers see occasional flashes of color. In reality, only a few are bothered to the point of annoyance by the rainbow effect, and most people aren't susceptible to the phenomenon. Technological improvements such as faster color wheels also have reduced the impact of the effect. However, until you try watching a DLP image, there's no way to know if you are affected.

In addition, many lower-cost DLP projectors are finicky about where they are placed relative to the screen, making finding a suitable location trickier than with a LCD projector. Higher-end DLP projectors often incorporate lens shift, which lets users slightly reposition the lens up, down, right or left, and makes finding a good spot for the projector a little easier.

LCD projectors once tended to suffer from what is known as the screen-door effect -- images sometimes would look like they would if you were viewing them through a mesh screen. However, advances in LCD technology have minimized the effect, and it is not a factor in high-def projectors. DLP projectors continue to handle fast motion better than LCD models. With LCD, blur or softening can be a problem with fast-moving objects in some scenes.

LCoS suffers from few of the drawbacks of other projection technologies. There's no color wheel, so rainbow effect is not an issue, and neither is the screen-door effect or excessive motion blur. Though performance can vary from model to model, in general, LCoS is well regarded for its deep blacks and good color performance. However, LCoS chips are expensive and difficult to produce, limiting them to more expensive home theater projectors. One drawback they have in common with all projectors is the use of a lamp that has to be replaced by the user from time to time.

Image size and brightness

Manufacturers usually specify a minimum and maximum image size for their projectors. Note that these are theoretical numbers that often have little to do with how an image will actually look. Typically, at the high end of the scale, the image will not be bright enough to look very good, while at the low end of the scale, images might be too bright. Because the required eyeglasses can cut down brightness considerably, some projector manufacturers are suggesting maximum screen sizes as small as 90 inches for 3D viewing.

For a projected image to look first rate, it needs to have sufficient brightness, which is defined by the Society of Motion Picture and Television Engineers as between 12 and 22 foot-Lamberts (fL), with an ideal of 16 fL. That recommendation is for a dark room such as a movie theater or a home-theater room with good to great light control. You'll need a brighter image for a typical living room -- figure 25 to 35 fL.

The best screen size for your home theater is determined by a number of factors, most notably projector brightness, screen gain, seating distance and the distance between the projector and screen (the throw distance). There are a number of good calculators on the Internet that do the math for you to make specific recommendations on optimal screen size for your specific projector. One of the best we've seen is at ProjectorCentral.com, which includes a database of almost every past and present home-theater projector, though some of the very latest ones have yet to be added. The calculator lets you easily experiment with different parts of the home theater equation to find things like the proper throw distance, seating distance, screen gain, and, of course, screen size.

Back to top