Brightness

Projector brightness is measured in lumens. For business projectors, that's one of the most important factors to take into account. The reason: The higher the lumen rating is, the less you have to worry about whether your images can be seen clearly. Experts warn that most manufacturer lumen ratings are inflated. They do, however, provide a convenient measuring stick for comparing projectors.

Projector experts say a 1,500-lumen projector will satisfy the needs of a typical business presentation -- one in a small conference room with low to average lighting and seating eight to 10 people. Most newer portable projectors have capabilities well beyond that. Lumen ratings of most standard-size digital projectors covered in this update range between 2,500 and 3,500 lumens. The 2,500-lumen models are suitable for use in a large meeting room about the size of a lecture hall. Those rated above 3,000 lumens will project well in a small auditorium. As a rule of thumb, price tends to increase with lumen ratings.

Pico projectors, which have very low lumen ratings, have become very popular among business users in the past few years in part because they're very small and portable. However, it's important to remember that they are most suitable for small meeting rooms and gatherings of no more than a few people because they are not particularly powerful.

Resolution

Portable digital projectors come in a variety of resolutions and aspect ratios. Native resolution measures the sharpness of the projected image and refers to a projector's true resolution without compressing the number of pixels (compression degrades image quality). SVGA (800 pixels by 600 pixels) and XGA (1,024 pixels by 768 pixels) digital projectors display images in a 4:3 aspect ratio. Some projectors, notably pico projectors, display images at VGA resolutions (640 by 480 pixels) in a 4:3 aspect ratio or WVGA, a non-standard format (see below) for wide-screen presentations.

As noted by Art Feierman of ProjectorReviews.com, XGA resolution gives you "clean crisp data on any sized text and graphics." Because of that, and because the price difference between XGA and SVGA projectors has closed dramatically, XGA is the most popular choice among full-size business projector buyers. Projectors with SVGA resolutions are still available, however, and since they are perfectly able to display the dozen or so lines of large text on a typical PowerPoint slide, they are a reasonable choice for buyers on a tight budget.

There has been an increase in the number of widescreen portable digital projectors. These digital projectors are offered in a number of native resolutions. Projectors with WVGA resolution (854 pixels by 480 pixels) match the full resolution of DVD movies, so you get every ounce of a DVD's image quality. WVGA is an unconventional standard that also includes resolutions of 800 pixels by 400 pixels and 848 pixels by 480 pixels. In fact, any display that's wider than VGA can be classified as WVGA.

Many widescreen business projectors have WXGA resolution. WXGA is another non-standard standard that includes several different resolutions. For business projectors, 1,280 pixels by 800 pixels is a popular WXGA resolution since it matches that of many 14- and 15-inch laptop displays. That resolution can also display widescreen, high-definition images of 1,280 pixels by 720 pixels or 1,024 pixels by 768 pixels without cropping or scaling.

Some digital projectors offer a native resolution of 1,400 pixels by 1,050 pixels called SXGA+. That matches the display resolution of many widescreen computer monitors and larger (17 inches and up) widescreen laptops. Some 14- and 15-inch laptops also have SXGA+ graphics.

Contrast, throw, lamp life and accessories

Contrast ratio refers to the difference between the darkest black and brightest white in a projected image. For data and graphics projections, editors at Laptop magazine say a ratio of 400:1 is sufficient. If you want to play video and DVDs, however, a contrast ratio of more than 1,000:1 means that dark scenes will be darker and more cinematic. Be forewarned that reviewers say manufacturer brightness and contrast claims are almost always inflated. They do, however, provide a convenient way to compare digital projectors, especially those from the same maker.

The term "throw" reflects the distance between the projector and the screen. In the past few years, projector manufacturers have introduced ultra-short-throw projectors that can be placed very close to the screen and still produce a large, clear image that's free of geometric or other distortion. That can really come in handy if you're traveling to unfamiliar conference rooms and have to set the projector up in a small or awkward space.

Digital projectors use lamps that must be replaced periodically. Average lamp life is about 2,000 to 3,000 hours, and replacement lamps can cost $300 or more. A few models of office projectors have long-life lamps rated to last longer; the lamps in the best-rated pico projectors last 20,000 hours. Although business projectors have warranties of up to three years, lamps are usually only under warranty for 90 days. Be sure to consider this in your long-term costs.

Some portable projectors also come with an array of accessories that may be important to you. Included features like a carrying case, fully functional remote control and a laser pointer are part of some projector packages.

Projector technologies

When you start shopping for a projector, you'll immediately notice that there are three projector technologies on the market: digital light processing (DLP), liquid crystal display (LCD), and liquid crystal on silicon (LCoS). However most portable business projectors use either LCD or DLP technology.

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, however. Single-chip DLP projectors (all but the most expensive DLP projectors fall into this category) 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. Only a small number of viewers are bothered to the point of annoyance by the rainbow effect, and most people aren't even susceptible to the phenomenon. However, until you try watching a DLP projector, there's no way to know if you are affected.

LCD projectors tend to suffer from what is known as the screen-door effect -- images sometimes look like they would if you were viewing them through a screen. However, advances in LCD technology have minimized the effect, and it is really not much of a factor in 1080p 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.

The final projection technology, liquid crystal on silicon (LCoS), is known for great black levels and contrast, as well as no rainbow effect. However, motion blur can be a problem with this technology. In the past, LCoS was typically associated with high-end projectors, but the technology is now appearing in lower-cost models, including pico projectors.

Here are a few other things experts say to consider when choosing a portable digital projector:

  • Consider room size. Experts say a projector rated at 1,000 to 1,500 lumens is fine for a small room with a lot of ambient light. For larger rooms, you'll want a projector rated at 1,500 to 2,000 lumens or higher. Pico projectors and micro-portable projectors are best for very small groups or one-on-one presentations because they're far less powerful (as little as a few dozen lumens) and cannot fill a large screen in a big room with their low-powered throw.
  • Consider contrast ratio. Manufacturer specs are often very different from tested results, partly due to vague standards for measurement. In general, business users can get by with a contrast ratio of 400:1.
  • Consider lamp replacement expense in your long-term costs. Standard lamp life is between 2,000 and 4,000 hours, and replacement lamps are not cheap. Some cost $300 and up. Some portable projectors now use LED lamps that have long lifetimes -- upwards of 20,000 hours -- so bulb cost is not a concern with those.
  • Make sure you have all the right connectors. VGA connectors are a minimum requirement for an analog connection to a laptop. DVI connectors are digital for improved signal quality. Composite (good), S-video (better) or component (best) video connectors are used to connect to a component DVD player or another video source. HDMI- or HDCP-compliant DVI inputs are used by more and more HD components as well as some computers and laptops.
  • Will you need a zoom lens, sound system or a remote control? Zoom lenses simplify the job of placing a projector. Otherwise, image size can only be adjusted by physically moving the projector closer or farther from the screen. Built-in projector speakers are usually unremarkable, but most can be connected to an external sound system for those instances where audio quality matters. Some projectors have remote controls that users find difficult to operate.
  • Use a projection screen for the best images. Projected images typically look best against a screen, although a light-colored wall will do in a pinch. Decide if it's worth buying a screen and if you want to lug one around with you.

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