If you're reading this article, you're either in the market for your first projector or you're a budding home theater enthusiast expanding your knowledge. Either way, we're happy to help. The joys of front projection are great and many, but it's not like buying a flatpanel TV. Front projectors are part of a two-piece system that includes a properly matched screen. And finding the right projector for your situation means choosing among three different potential light sources and three different imaging technologies, and then insuring that the projector has enough brightness for your environment and desired screen size—not to mention sufficient contrast and color accuracy to do justice to your favorite movies, TV shows, and sports broadcasts. It's a lot for newbies to get their heads around.

 

In this two-part article, we'll teach you just about everything you need to know. Here in "How to Buy a Home Theater Projector, Part 1: Behind The Lens," you'll learn all about the different parts of a projector and some basics on projection screens. In "How to Buy a Home Theater Projector, Part 2: Step by Step to Your New Home Theater," we'll take you through the process of buying a projector: how to determine your throw distance, screen size, and brightness requirements; which projector features are most desirable; and how to use ProjectorCentral's extensive projector database and online resources to zero in on your short list of models. So let's get on with it!

Why Projection?

There's more benefit to a dark home theater illuminated by a 100-inch or larger screen than the warm, nostalgic reminder of your local cinema. Simply put, when it comes to watching movies or playing video games, bigger is always better. Sitting at appropriate distance from a large projected image engages more of your peripheral vision, lets you see details that are lost on most TVs, and sucks you into the story in a way that's just not possible with even a 75- or 85-inch flatpanel. If you have the will power to turn off your phone like you do down at the cineplex, it makes movie viewing a true escape.

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No panel television can beat the immersion and engagement of a giant, projected image. (Image: Aneta Pawlik)

Here's an easy demonstration you can try. Go stand by your window and take in the outdoor scene in all its action and glory—the width, depth, and breadth of it. Children playing in the yard, wind blowing through trees, cars whizzing by on the street. Now step back 10 feet and look through the same window. The scene and characters are the same, but they are shrunk to less than lifelike, and you're viewing them through a picture frame. This is how most people watch on a 55- or 65-inch TV from average viewing distance. What they're really seeing is an image of their home furnishings surrounding a window with tiny, animated figures dancing about in it. This is why no one would ever mistake watching TV with being at a movie theater.

On the other hand, a properly executed projection home theater is very effective at mimicking the theatrical experience and its high level of engagement. And projectors remain—by far—the most cost effective way on a per-inch basis to attain pictures of 100-inch diagonal or larger.

There's something else that's special about projected images, something you probably already know intuitively just from going to the movies. Unlike a television, which blasts your eyes with bright, emissive light, a projection comes to you as a reflection off the screen. That's how we view most objects in life—we see the ambient light bouncing off them. Consequently, there is a more natural-looking, organic quality to projected images. You experience less viewing fatigue, and the picture better communicates the film-like—and lifelike—aesthetic that cinephiles so appreciate.

Now, I know some of you might say, "Okay, that's great. But when I'm not hunkered down with a bowl of popcorn for movie night, I like to watch TV with the lights on. You can't do that with a projector."

Well...not so fast. It's true that you'll always get the best performance from any projector in a dark room. But today's breed of ever-brighter projectors, mated with the latest ambient-light-rejecting screens, can function just like an everyday TV in high ambient light. There's even a new class of ultra-short-throw living room projector designed from the ground up just for this purpose. We'll say more about ALR screens and these specialized UST projectors later.

What's Inside a Projector?

Before you wade into the projector shopping process it's helpful to understand their parts and how they work.

In the most simplistic terms, every modern digital projector has three primary components:

  • A light source that creates the light for the image. In today's projectors this will be a traditional lamp, a bank of laser diodes, or a bank of LEDs (light-emitting diodes).
  • An imaging chip or chips that generate the image based on the video source signal. This will typically be either a single Digital Light Projection (DLP) micromirror device, a trio of LCD (liquid crystal display) panels; or a trio of LCoS (liquid crystal on silicon) chips.
  • A lens and associated optical elements, which are used to introduce color to what would otherwise be a black-and-white image and to project the image onto the screen.

Each light source has its own special strengths and limitations, as does each imaging technology. And lenses have their own particular attributes.

Projection Light Sources

Our Tech Talk article "Lamp, Laser, or LED Projection: Which Light is Right?" gives you the deep dive on projector light sources and their differences. Here's a quick overview.

Lamps. Traditional lamps still dominate the home theater landscape for reasons of both cost and efficacy for dark-room viewing applications. They can be specified to get just bright enough to provide punchy pictures on a big 100- to 150-inch screen, but not so bright that the projector's baseline black level and contrast look unreasonably gray and washed out. The brightness of a lamp projector is also easily mitigated scene-by-scene with a dynamic iris, which partially shutters the lamp's output to deliver better contrast on dark material.

The downside? Lamps run hot, drift slightly in color balance as they age (therefore requiring more frequent calibration of the projector to maintain perfect accuracy) and eventually need replacement. Most are rated for around 4,000 hours of viewing in the projector's brightest picture mode before reaching their half-life, or half the brightness of a new lamp. This period may be extended if you don't need to run the projector at its full power, but when a lamp reaches half-life, it should be swapped out. You'll want to check the replacement cost of the lamp for whatever model you intend to buy so you'll know what you're in for. Many people push their lamps way past half-life, but doing so will noticeably affect brightness compared with what you saw on the new projector.

08 Projection Replacement Lamp
Projection lamps need periodic replacement to restore the projector to its initial brightness. How many replacements depends on the hours of use and how bright the projector is set up to run. (Image courtesy of Epson.)

Laser. Solid-state laser light engines are rapidly taking over the commercial projector market. With no lamp replacements needed over the 20,000-hour life of the projector and low or no maintenance requirements, it's easy to see why. However, while the cost of the blue-laser modules used in most of these projectors continues to drop, laser has not yet strongly permeated the home theater arena. Sony and JVC use lasers to drive their highest-end models, but some lower-priced laser projectors targeted at home theater have proven to perform well below similarly priced lamp-based models in terms of color gamut, color accuracy, and contrast. If the fear of lamp replacements is enough to put laser high on your list, be sure to read the product reviews carefully, and stick with those projectors designed from the get-go for home theater. Be prepared to pay a significant premium over lamp-based models to get similar dark-room performance.

05 Laser light path 1DLP
A typical single-laser projector has a blue laser whose light encounters a phosphor wheel to generate yellow that is then broken into red and green components. (Image courtesy of Maxell.)

That said, if your goal is to use your projector as a TV replacement in your lit-up family room, the newest generation of 4K UST laser projectors represent an important exception to this rule. In this scenario, the high brightness from laser is a plus. Likewise, its potential limitations on low black level aren't noticeable in moderate-to-bright ambient light, and the best models provide more-than-acceptable contrast in both dark-room and bright-room viewing when mated with an appropriate ALR screen. You can learn much more about this new class of projector in ProjectorCentral's special section, The Ultimate Guide to 4K UST TV Projectors, where we have a full product listing and other resources.

LED. LED's have the advantage of running cool and providing a compact light source that, like laser, never needs replacement for the life of the projector. This makes it ideal for briefcase- or even pocket-friendly portable DLP projectors, not to mention a few slightly larger carry-along lifestyle projectors. Unfortunately, with rare exception, the basic brightness limitations and inherently wide light-spread from LEDs has prevented this technology from delivering the kind of punch required for serious big-screen home theater. This statement even takes into account the oft-repeated fact that light from LEDs is perceived as brighter than light coming from a lamp—a phenomenon you can read about here. But, as noted in "Laser vs. LED: What Does the Future Hold?," manufacturers are working on solutions, and we're starting now to see the first full-tilt home theater projectors with LED light engines. As with any emerging technology, make sure you watch for positive reviews from us and other experts before you buy.

Projection Display Technologies

ProjectorCentral has an in-depth Tech Talk article titled "LCD, LCoS or DLP: Choosing a Projector Imaging Technology," that provides a helpful and detailed resource on this subject. Here are the basics.

DLP. By far the most popular technology found in projectors of every type and size, Digital Light Projection is an invention of Texas Instruments that has revolutionized the projection world. DLP projectors utilize one or more electro-mechanical imaging devices called DMDs, or Digital Micromirror Devices. These present an array of tiny, pixel-sized mirrors to the light source—as many as 8.3 million in a native 4K-resolution DMD measuring just 1.38-inches wide. The mirrors each pivot on their own post, and can be independently positioned to direct a point of light to the screen or to dump it into a light-absorbing area, thus leaving that pixel dark. The mirrors oscillate at different speeds to brighten or darken the pixels as needed.

LCD LCoS DLP Fig10
DLP projectors use DMDs covered with pixel-sized micromirrors that independently pivot between two positions. (Source: Texas Instruments)

Though there are some high-end commercial and digital cinema DLP projectors that use three DMDs to simultaneously serve up the red, green, and blue color components of the image, the vast majority of DLP projectors use a single DMD chip to save cost. This makes very high quality home theater and portable projection available to consumers at relatively low prices, but also creates an important distinction between DLP and the other imaging technologies in terms of how they create color. Like those high-end DLP projectors, LCD- and LCoS-based home theater projectors utilize three separate chips to simultaneously present the red, green, and blue elements, which get overlayed and combined into a full-color image. However, single-chip DLP projectors present these individual color images sequentially by passing white light through a translucent, spinning wheel with (at the least) red, green, and blue filters. The different color components of the image are presented so rapidly that the eye blends them together and sees them as full color.

LCD LCoS DLP Fig14
1-chip DLP projectors typically use a color-filter wheel to sequentially flash the different red, green, and blue color images on the screen; this happens so quickly that our eyes blend them together into a full-color image. (Source: Upgrade Magazine)

There are two possible drawbacks that accompany the use of a sequential color wheel in any projector: (1) the potential for rainbow artifacts, in which fleeting rainbow-like banding may appear on the edges of some objects; and (2) unequal white and color brightness, which may result in some colors looking less saturated or accurate. Some viewers are more sensitive to rainbows than others, and some projectors generate more rainbows by virtue of their design. Fortunately, engineers at the major DLP home theater projector brands, including Optoma, BenQ, and ViewSonic, have figured out how to minimize rainbows in modern projectors. Still, we always report on this phenomenon in our reviews and always recommend that, if you're sensitive to rainbows or don't know if you are, you should buy from a reputable retailer who will accept a return or swap.

 

Meanwhile, the subject of color vs. white brightness remains somewhat controversial. Not every 1-chip DLP projector suffers from lower color brightness compared to white, but this is a real and demonstrable phenomenon on models that use a clear (white) segment in their color wheel to boost ANSI lumens and overall brightness. Projectors that feature DLP's Brilliant Color technology usually have a control to adjust the white/color brightness balance. Nonetheless, for all the criticism leveled at this DLP shortcoming—usually from the 3-chip LCD and LCoS camps—it's not likely to create a bothersome or even noticeable performance difference for most viewers. ProjectorCentral explored this topic in detail in our article "ANSI Lumens vs Color Light Output: The Debate between LCD and DLP." You can also read more about this in the "3-Chip vs. 1-Chip DLP" section of the previously referenced article comparing LCD, LCoS, and DLP technologies.

LCD. LCD projectors shine a light source through translucent liquid-crystal panels whose pixels can be individually opened or shuttered by the video signal to make them brighter or darker. As noted, LCD projectors typically employ separate LCD imaging chips for the red, green, and blue picture elements, hence the "3LCD" branding associated with them. At this writing, several projector manufacturers make 3LCD projectors for business, education, and other commercial applications, but Epson remains the only major brand selling LCD projectors targeted for home theater.

LCD LCoS DLP Fig1
In LCD projectors, white light from a lamp is split into its red, green, and blue components and each is passed through an LCD imager. The light from the three panels is combined into a full-color image that is projected onto the screen. (Source: Epson)

LCoS. LCoS, or liquid-crystal-on-silicon, is a variant of LCD. Instead of light passing straight through the LCD panel, it is bounced off a reflective surface at the back of the chip. Light enters through the front, hits the reflector, bounces out, and is then directed through the lens and to the screen. It's more expensive than LCD but offers some key benefits, including the valuable potential for lower native black level and high contrast. As with LCD, three separate LCoS chips are dedicated to the red, green, and blue components and their images are overlayed to create the full color image. Only two manufacturers make LCoS-based home theater projectors: JVC, with its D-ILA (Direct-Drive Image Light Amplifier) technology, and Sony with SXRD (Silicon X-tal (crystal) Reflective Display).

LCD LCoS DLP Fig5
An LCoS imager includes a layer of LCD material that lets more or less light through each pixel according to the signal it receives. The light passes through the LCD layer and reflects off a mirror before passing back through the LCD layer a second time. LCoS projectors are known for delivering low native black level and good contrast. (Source: JVC)

Lenses. It's easy to understand that you could have a detailed, high-resolution imaging chip in a projector whose sharpness would be undermined by a poor quality lens or other optical elements placed in the light path. The best lenses are made of high quality glass, with multiple elements (and "groups" of elements) that help eliminate aberrations—usually, the more elements, the better and more expensive the lens. Today's 1080p-resolution budget projectors in the $500 to $1,000 range from the major brands come with surprisingly good lenses and deliver sharp and essentially uniform images. When you step up to UHD/4K-resolution, the lens requirements shoot up, which—along with the more expensive imaging chips—is a factor in the higher cost of 4K projectors. If you read the marketing blurbs for a projector and the manufacturer has gone out of their way to tout the optical quality of the lens (beyond mentioning its zoom or lens-shift features), it's because they want you to know they've paid attention to this important component and that it's one of the things you're paying a premium for.

BenQ 14 element 6 group lens
A high-end lens, with multiple groups and individual elements, are the hallmark of better projectors. This is an exploded view of the lens from BenQ's top-of-the-line home theater projector.

Beyond their basic optical quality, the lenses on home theater projectors often have some degree of optical zoom capability, and possibly vertical or horizontal lens shift functions. We'll explain these features later in Part 2 of this article.

Projection Screens

There's a tendency among first-time projector buyers to think they can dismiss the screen completely. Don't do that. Using a white or off-white wall may work out for casual viewing from an inexpensive portable projector, but if you're serious about getting the benefits of front projection in a home theater or family room you have to have a screen.

You'll have three decisions to make about your screen besides the diagonal image size: the frame design, the aspect ratio, and the screen material.

Frame Design. Most people end up with a fixed-frame screen design for direct mounting to a wall or for hanging from the ceiling. The bezel can end up being anything from a 3-inch black felt-wrapped border that hides any stray image spilling off the screen material, to a fine, nearly invisible bezel that gives the impression of an image floating in space. Although screen material can greatly affect the cost of a screen, fixed frame options are always the least expensive for any given material.

The usual alternative to a fixed-frame screen is some kind of mechanical or motorized retractable screen that drops down from the ceiling only when needed. These come in flush-mount styles with a canister that attaches to the ceiling, or in-ceiling versions that hide the rolled-up screen entirely in the ceiling but obviously require more involved installation. Motorized screens typically require some kind of low-voltage power cabling or a nearby power outlet, though battery-rechargeable screens are now available from some manufacturers. Motorized screens can also usually be dropped or stored with a trigger wire from the projector or other equipment, or via wireless remote control.

Draper Onyx fixedframe 2
StewartFilmscreen StealthRetractable
Fixed frame screens, like the Draper Onyx screen used in the custom home theater shown above, are the most common and typically have a black bezel that absorbs any stray light that spills off the edge of the image. Retractable screens, such as the Stewart Filmscreen Stealth screen below, may be mounted in a flush-mount canister or disappear fully into the ceiling when not in use. Better versions often have tab-tension edges that help keep the screen surface flat.

Aspect Ratio. Aspect ratio defines the relationship of the screen's width to height, and will be selected to match one of the common content formats used today. The vast majority of installations use a screen with a 16:9 aspect ratio, or 16 units of width to 9 units of height. This matches HDTV broadcast and game content and the native aspect ratio of the imaging devices found in most home theater projectors, but results in widescreen movies appearing with black letterbox bars at the top and bottom of the screen. Some serious movie enthusiasts opt for a 2.4:1 aspect ratio, which closely matches widescreen theatrical movies, but typically results in black pillars appearing to the left and right with 16:9 HDTV content. There is a lot to consider before planning a 2.4:1 screen installation that will affect the projector you select and how you use it. Our article "When Widescreens Work: How to Pick the Right Aspect Ratio" will give you some additional background.

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Aspect Ratio 235
Above: a 16:9 (1.78:1) aspect ratio image, typical of what most see with HDTV viewing and video gaming. Widescreen theatrical movies appearing on a 16:9 screen are often "formatted to fit the screen" via a process that sacrifices image information at the far left and right of the screen. Below: a 2.4:1 widescreen aspect ratio image common with many movies released on Blu-ray and from streaming services. Notice the extra detail to the left and the right that is not present in the 16:9 aspect ratio presentation.
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Letterboxing on 239 screen
Above: Pillarboxing effect caused when a 16:9 image is displayed on a 2.4:1 aspect ratio screen. Below: Letterboxing effect caused when a 2.4:1 image is displayed on a 16:9 aspect ratio screen.

Screen Material. The screen material you select will vary based on your need to combat ambient light. If you're planning an installation for viewing in a dark room or one with only moderate light not directly washing on the screen, you can use a traditional matte white screen material that will best maintain brightness and color accuracy while providing a smooth texture. White screens are also usually the most cost effective. Gray screen materials boost perceived black level and contrast, usually at the expense of some brightness, and can be an option for dark and moderately-lit viewing spaces. For bright-room viewing, more sophisticated, engineered ALR materials with multiple layers of optical elements will actively direct the projector light back to the viewers while rejecting ambient light to different degrees. You can read about the different types of ALR screens and how they work in "Screen Magic: How UST Screens Let You See the Light."

EliteCinegrey3D vs Matte White2
Modern ALR screen materials take projectors out of the dark and into the light of your living room. Shown here is the Elite Screens Cinegrey 3D shown next to a matte white screen photographed in the same light conditions.

For situations where a fixed or drop-down screen will obstruct a home theater speaker system, you can opt for an acoustically-transparent screen. These allow sound to pass through, though the perforations or weave in the material can sometimes cause visible artifacts depending on the material used. It's best to avoid these screens if you can to better protect both the image and sound quality of your system, but the best acoustically transparent screens minimize the deleterious effects on both.

Screen Gain and Viewing Angle. There are two primary characteristics you'll want to pay attention to with any kind of screen material you're considering. The screen's gain describes its reflectivity, where a gain of 1.0 suggests even reflection—all the light coming in comes out with the same brightness. A 1.0 gain screen will also have the most uniform distribution of light across the entire screen surface, while higher gain screens will exhibit some degree of hot-spotting at the center. Most traditional matte white screen materials are rated from 1.0 to 1.3 gain, with higher gains providing more perceived brightness to viewers sitting in or near the center sweet spot.

screen gain comparison2
As screen gain increases above 1.0 (far right), the image gets brighter, but the width of the viewing cone decreases and the screen may exhibit visible hot-spotting.

The second key characteristic is the screen's half-gain viewing angle or viewing cone, which describes the how far viewers can move to the left or right of center screen before brightness noticeably drops off. Screens with higher gain above 1.0 will direct more light down the centerline but have a more narrow viewing cone. Our article "What is Screen Gain" will tell you more.

Click here to proceed to "How to Buy a Home Theater Projector, Part 2: Step By Step to Your New Home Theater."

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