Computer projectors cast a greatly enlarged version of the computer screen onto a movie screen, or even a clear white wall.
The bad news about computer projectors is that they are costly; the good news is that prices are falling. Some are designed to be used in conjunction with home theatre systems. Others are education or business-oriented. Typically, you would use one of the latter to help you illustrate a talk, or to convey information in conjunction with a lecture or speech or talk before a medium or large audience. A multimedia projector can project images from various sources, such as a DVD player or laptop computer. Multimedia projectors can produce such good video quality that many people are replacing their TVs with a projector and screen for an enhanced home theater experience. Multimedia projectors come in three types: Cathode Ray Tube (CRT), Liquid Crystal Display (LCD) and Digital Light Processing (DLP).
CRT projectors emit images like a TV, consisting of red, green and blue light. They cost nearly twice the price of LCD and DLP projectors. CRT projections should be used in dark rooms; otherwise light will overwhelm the image. They're big, bulky and hard to move. They can be costly to maintain; if one of the color tubes fails, you will need to replace all three. However, their images are crisp at any resolution and have a full range of colors, including the blackest blacks, and they provide the most authentic cinematic movie experience.
LCD projectors project light images through small, transparent panels. They're smaller and more portable than CRT projectors. To use such a projector for home theater, be sure to shop for one designated specifically for home theater use. Less expensive office models tend to have lower resolutions.
LCD projectors are much cheaper than CRT projectors. LCD projectors put light through tiny pixels onto a big screen, and the image can sometimes look pixilated or blocky, as though you are viewing it through a screen door. If a pixel burns out it will display as a black or white dot on the screen and the only way to fix this is to replace the whole chip. An LCD Projector's image resolution is limited by how many pixels its chip has. If it has only a 1024x768 resolution chip and you are watching high definition TV, the image will be less sharp and detailed than that from a CRT projector. They produce a fan noise, and you must replace the light source after each 1,000-2,000 hours of use. They're compact, lightweight and highly portable, and their power consumption is low. They produce good colors, high contrast, and high image quality in partially lit rooms.
DLP projectors emit light through a transparent chip onto a tiny mirror array, which gives good quality, high definition images. However, they suffer from having a fixed resolution like LCD projectors. They need a replacement light source about every 1,000 hours to keep images sharp, but they work for both office and home theater use and do not suffer "screen door effects" like LCD projectors. DLP projectors are just slightly more expensive than LCD projectors. They use little energy to produce high quality images with vivid colors and high contrast, even in partially lit rooms. They're more durable than LCD projectors.
Before buying, you need to answer six important questions:
Which aspect ratio do you want? Aspect ratio is the width-to-height relationship. Movies made before 1953 used a ratio of 4:3, while the current HDTV standard is 16:9, and today there is considerable interest in the dedicated super-widescreen ratio of 2.35:1. If you like to watch the Oldies, choose 4:3, if you want to be with it today, choose 16:9. If you are captivated by HDTV or future oriented, choose 2.35:1. There are some compromise in/between ratios, but why compromise?
What resolution is best for you? A projector's resolution is the number of pixels it has available to create an image, the higher the better, but the more costly the projector will be. If you can afford it, make sure that the native resolution of the projector matches the native resolution of your computer. The currently most popular home theatre resolution is 1280 x 720, and for most people it is probably the best value-for-money choice today.
How bright should it be? For home theatre applications, 2,000 lumens may be quite enough, but for business applications, if you want to make presentations without turning the lights down, get a projector with at least 2,000 lumens and preferably a good bit more. Don't be fooled by some manufacturers who overstate the lumen ratings of their machines; read objective lab testing reviews.
How much contrast do you need? The contrast ratio relates to the relationship between brightness and darkness. Many LCD projectors have a contrast ratio of 400:1, which means that the lumen output of a projected white image is 400 times greater than that of a projected black image. This is enough, but just barely. If your eyesight is less than normal, get more if you can afford it.
What are your installation constraints? If you get a CRT model, plan to stick it somewhere and leave it there, and plan simply to rent another type model for specific meetings/talks, etc. Meeting venues often have their own units, which you can simply requisition, but check in advance to make sure. The LCD and DLP models are portable, and can be hauled out for educational or business use, and then brought back home.
What will it cost? There is a fairly wide range here, from under $300 to more than $2,300, so these items are sufficiently costly that you should first read some assessments by neutral and objective reviewers.
- There are many online sources of this information, such as Consumer Reports (www.ConsumerReports.org). You can access free Consumer Reports online courtesy of your local library (www.accessmylibrary.com). Also you can consult the Consumers’ Web Watch (www.consumerwebwatch.org), the Consumers’
Here are some suggested requirements for a home theater projector, if you can afford them:
Projector Type: LCD Native Resolution: XGA 1024 x 768 Maximum Resolution: UXGA 1600 X 1200 Brightness: 2000 lumens HDTV Projector: HD Ready Aspect Ratio(s): 4:3, 16:9 Projection Distance: 3 - 35 ft Contrast Ratio: 400:1 Horizontal Frequency: 15 - 91 KHz Price: Starting around $800
Business Presentations DLP projectors work well and are portable for multimedia (text, graphics and video) presentations. Buy (or rent) a unit with built-in audio and a remote control. Make sure it is lightweight (3-8 lbs.) since you will also have a carrying case and cables. Most multimedia projectors are Plug-and-Play, but be sure the model you are considering will work with your PC's operating system. Some projectors are not Mac-compatible or may require extra software to work with a Mac.
Here are suggested requirements for a multimedia business projector, again if you can afford them:
Projector Type: DLP Native Resolution: XGA 1024 x 768 Maximum Resolution: UXGA 1600 X 1200 Brightness: 2000 lumens or preferably better HDTV Projector: HD Ready Aspect Ratio: 4:3 Projection Distance: 4 - 24 ft Contrast Ratio: 2000:1 Horizontal Frequency: 15 - 80 KHz Price: Starting around $1,500
p.s., A computer projector glossary can help you understand the lingo concerning these machines.A good one resides at: http://www.avpartner.com/Glossary.aspx
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