Macy is my seven-year-old niece who loves to shop. At her tender age, she's already developed a solid sense of fashion and has a keen eye for color. The only problem is when faced with a multitude of options, she just can't make a selection. A recent shoe shopping expedition, for example, stretched over three days with visits to dozens of locations. There were simply too many choices and she couldn't decide.
Educational technology leaders face a similar struggle when trying to select and buy a data projector. ProjectorCentral.com, the leading source of consumer information on the projector industry, lists more than 50 manufacturers, each offering at least six different models with some selling more than 20 varieties. All told, technology decision makers have over 500 different projectors to sort through—a daunting process. Here, key questions to help you narrow down your search and make a wise buying decision.
- LCD or DLP?
There are two fundamental projection technologies: LCD (liquid crystal display) and DLP (digital light processing). When Texas Instruments introduced DLP almost a decade ago, the technology promised to take over the industry with its high contrast ratios and deep image quality. However, led by major companies such as Sony, LCD technology has made significant improvements to keep the playing field basically level, although LCD manufacturers argue they have the advantage over DLP in terms of color saturation and image sharpness.
The bottom line is both LCD and DLP manufacturers will continue to improve image quality with every generation of projectors, and it's unlikely you'll notice significant differences in the two technologies when using them for typical classroom functions such as PowerPoint presentations and displaying Web sites. The higher contrast ratios offered by DLP, however, are helpful when working in less than ideal ambient light situations.
Brightness: Projector manufacturers give brightness, or lumen count, far and away the most attention when marketing their products. Light output is extremely important. All other things being equal, the brighter a projector, the better the image. In the education market, the typical projector provides approximately 1000 lumens of brightness, which is suitable for almost all classroom situations. Projectors of over 2000 lumens work well in large classrooms, auditoria, or media centers that have moderate to high ambient lighting. To determine your brightness needs review the following considerations:
Image Size: The larger an image, the dimmer the image will appear as the light from the projector is spread over a larger area. It follows, then, that you'll want a brighter projector with 2000 lumens or more if you plan to consistently project large images.Ambient Light: Regardless of the brightness of the projector, darker rooms provide better image quality. However, completely darkening a classroom is usually impractical and ill advised-students need sufficient light to take notes and teachers want to be able to see into every corner of the room. If there's no way to dim the lights or at least partially cover windows, a brighter projector will be needed.Screen Quality: Investment in high-quality screens with high levels of reflectivity can help overcome image quality issues of a low brightness projector. If screens are not available, a brighter projector will help dramatically since most walls in schools have relatively low reflectivity.Presentation Material: If the projector is used exclusively for graphic presentations such as PowerPoint and video, you can compromise on brightness since they require relatively low levels of detail. For situations in which applications such as spreadsheets will be shared, and a greater level of detail is required, a brighter projector is warranted.Budget: Brightness comes at a cost. Doubling the brightness of a projector from 1000 lumens to 2000 lumens, for example, can drive the cost up as much as four times.Lamp Life: Because of wide variance in the technology used in projector lamps, there's no clear relationship between the brightness of a projector and its lamp life. Generally speaking, however, the brighter a projector runs, the shorter its lamp life. Many projectors allow users to adjust the brightness and thereby extend lamp life-a significant consideration as replacement lamps cost $200 to $400 each.
Contrast Ratio: While brightness is the single most important factor in determining image quality, the contrast ratio can make a tremendous difference in high ambient light situations. Contrast ratio is a measure of the difference between the brightest and darkest areas of the image. A contrast ratio of 400-to-1 means that the brightest part of the image is 400 times brighter than the darkest part of the image. A higher contrast ratio provides more subtle detail in shading and color differences. In some cases, a budget projector with high contrast ratio can make up for its relative lack of brightness.
Resolution: The amount of information displayed on the screen is determined by the projector's resolution. Resolution is quoted as two numbers, such as 800x600, meaning an image is 800 pixels across and 600 pixels tall. The more pixels, the higher the resolution, and therefore, the more detailed the image. SVGA (800x600) and XGA (1024x768) projectors are the most widespread and affordable. SXGA (1280x1024) and UXGA (1600x1200) projectors are very expensive and typically reserved for specialized uses.
How do you know which resolution you'll need? First, pick a projector that will display appropriate detail for the applications you will be using. If you're primarily using the projector for PowerPoint presentations with slides, charts, and graphs, then SVGA resolution will be more than adequate and most cost effective. If, on the other hand, you need to project detailed materials such as spreadsheets, then an XGA machine is better.
Second, look for a projector that matches the resolution of the computer you will be using to create the images. Laptop computers, like projectors, have a native resolution. Using an SVGA laptop with an SVGA projector (or an XGA laptop with an XGA projector) will produce the best image because no compression or expansion of the image data is required.
Throw Distance: We all know the further we move a projector from the screen, the larger the image will appear. But some projectors are designed with wide-angle lenses that allow for relatively short throw distances, meaning you can project a large image from close range. This consideration is particularly important if the projector will be used in small classrooms or offices where it's difficult to move the projector long distances from the screen.
The hottest innovation in projectors is wireless connectivity. Many manufacturers now offer projectors with 802.11b wireless connectivity built-in or available via a PC card slot. Dell's 4100MP, for example, includes a wireless network card allowing users to give PC-free presentations from a wireless-equipped PDA. Wireless projectors are just beginning to reach a price point palatable for most schools with 1000-lumen SVGA wireless projectors starting at $1,200.
Other manufacturers have moved to make projectors interact seamlessly with memory storage devices used in handheld computers and digital cameras. For example, Epson's PowerLite 835p includes a slot that accepts compact flash, memory stick, SD, and other memory cards. Users can save their files to the memory card and using integrated software give presentations or display files directly from the projector.
Blackboard Mode: Frequently, educators must use projectors in rooms without highly reflective screens. Canon and Epson offer projectors with a blackboard mode for use when projecting directly on a blackboard or chalkboard. The projector detects the color of the display surface and adjusts its color output to optimize the image reproduction.
Document Camera: Document cameras are a potential replacement for overhead projectors. These cameras are designed to capture live video of objects placed on a flat stand below the suspended camera. Teachers can use a document camera to display samples of student work, provide close-up views of small details in a science experiment or display handwritten notes. In the TDP-T91U model, Toshiba combines a document camera with a projector. The top of the projector serves as the document stand and the image is projected for easy viewing by the entire class.
ASK Proxima (a brand of InFocus)
C110: 1600 lumens; SVGA resolution; 2000-to-1 contrast ratio
C170: 2000 lumens; XGA resolution; 200-to-1 contrast ratio; wireless capability
PB6100:1500 lumens; SVGA; 2000-to-1 contrast ratio
PB6200: 1700 lumens; XGA; 2000-to-1 contrast ratio
SP-48z: 1400 lumens; SVGA; 500-to-1 contrast ratio
CD-726c: 2500 lumens; XGA; 1800-to-1 contrast ratio;
(800) 652-2666 www.canonprojectors.com
LV-X4: 1500 lumens; XGA; 400-to-1 contrast ratio; blackboard mode
LV7215: 3000 lumens; XGA; 350-to-1 contrast ratio
2200MP: 1200 lumens; SVGA; 1700-to-1 contrast ratio
4100MP: 2200 lumens; XGA; 2000-to-1 contrast ratio; card slot for PC-free presentation
ImagePro 7300: 1600 lumens; SVGA; 2000-to-1 contrast ratio
ImagePro 8757: 2500 lumens; XGA; 800-to-1 contrast ratio; built-in networking
ImagePro 7300: $2,449
ImagePro 8757: $5,995
PowerLite S1+: 1400 lumens; SVGA; 500-to-1 contrast ratio
PowerLite 835p: 3000 lumens; XGA; 600-to-1 contrast ratio; wireless connectivity
PowerLite S1+: $999
PowerLite 835p: $4,094
vp6111: 1500 lumens; SVGA; 2000-to-1 contrast ratio
mp3220: 2000 lumens; XGA; 2000-to-1 contrast ratio
CP-S210: 1200 lumens; SVGA; 300-to-1 contrast ratio
CO-X328: 2000 lumens; XGA; 350-to-1 contrast ratio
X1a: 1100 lumens; SVGA; 2000-to-1 contrast ratio
LP640: 2200 lumens; XGA; 400-to-1 contrast ratio; wireless ready
Solid ultra: 1600 lumens; SVGA; 600-to-1 contrast ratio
dv500: 3500 lumens; XGA; 800-to-1 contrast ratio; network and wireless ready
Solid ultra: $1,295
VX2: 1000 lumens; XGA; 200-to-1 contrast ratio
CX4: 2000 lumens; XGA; 400-to-1 contrast ratio
SE1U: 1200 lumens; SVGA; 400-to-1 contrast ratio
XD400U: 2200 lumens; XGA; 200-to-1 contrast ratio
VT47: 1500 lumens; SVGA; 400-to-1 contrast ratio
VT670: 2100 lumens; XGA; 400-to-1 contrast ratio
PT-LM1U: 1200 lumens; SVGA; 400-to-1 contrast ratio; one-touch set-up feature
PT-L500U: 850 lumens; high definition video resolution; 1300-to-1 contrast ratio
U5-111: 1600 lumens; SVGA; 2000-to-1 contrast ratio
U5-232: 2000 lumens; XGA; 2000-to-1 contrast ratio
PG-B10S: 1200 lumens; SVGA; 350-to-1 contrast ratio
PG-C45X: 2500 lumens; XGA; 400-to-1 contrast ratio; low power mode to conserve lamp life
VPL-CS7: 1800 lumens; SVGA
VPL-CX75: 2500 lumens; XGA; wireless transmission system (Note: Sony does not provide contrast ratio information)
TDP-S20U: 1400 lumens; SVGA; 2000-to-1 contrast ratio
TDP-T91U: 2000 lumens; XGA; 2000-to-1 contrast ratio; detachable document camera
TDP-S20U: $999 (wireless model: $1,199)
PJ510: 1200 lumens; SVGA; 300-to-1 contrast ratio
PJ650: 2000 lumens; XGA; 350-to-1 contrast ratio
Feature Cheat Sheet
11 considerations to bear in mind when selecting a projector.
LCD vs. DLP
- Differences are minimal for most educational uses
- Better contrast ratios of DLP may be better for high ambient light situations
- Pick first for brightness and then for contrast ratio
- Match resolution of projector to computer
- Consider short throw distance and keystone correction as extra features
- Wireless connectivity is the latest new feature in projectors
- Wireless is useful for rapidly switching between multiple inputs
- Smaller projectors provide flexibility, but at the cost of some advanced features and physical security
- Blackboard mode helps compensate when projecting without a screen
- Bundled document cameras can project paper and 3-D objects
- Copyboards can be used for annotating and saving images
Todd McIntire is a vice president at Edison Schools, Inc. He is currently involved in developing Edison's new division in the United Kingdom.