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Data Projector Buyer's Guide
Brightness
 

Projectors come in a wide range of light outputs, which are measured in ANSI lumens or just "lumens" for short. The brighter the projector, the higher the ANSI lumen rating, and (all else being equal) the more it costs. Contrary to popular belief, brighter is not always better, and there is no hard and fast rule regarding optimum lumen output. However, there are certain factors to consider to make sure your projector is neither too bright nor too dim for your intended use.

Things to Consider When Choosing Brightness

There are four primary considerations when choosing your projector's brightness.

  1. How many people will typically be in the room? This determines the size of the projected image that is required for easy viewing by everyone present. As the number of people in the room increases, the image size must increase. This diminishes the perceived brightness of the projector as the light is spread over a larger area.
  2. How much light is in the room? A dark room will provide the best image regardless of projector brightness. However, most meetings require some lighting for note-taking and eye contact. A room where the lights cannot be turned off or dimmed from within the room or where windows cannot be blocked or covered will require a bright projector. The same bright projector placed in a perfectly dark room will likely give your audience a headache, so this is a critical factor.
  3. What kind of projection screen is available? This can have a profound effect on the image brightness and quality. Most projection screens today provide significant light reflection, making even a relatively low brightness projector look good in the proper setting. If the room lacks a projection screen, as is sometimes common in a mobile sales presentation, you will be better served by a high brightness projector since walls are poor reflectors of light.
  4. What is your application? Applications such as training and workgroups will demand more brightness because these applications also require more room light for note taking and communication. Applications that use presentation graphics, photographs, or video are more likely to be shown in a darkened room, and therefore do not require as much light output. If the projector will serve multiple locations either within a building or because of traveling, consider your most demanding setting.

In today's market, projectors can be grouped by ANSI lumen output as follows:

  • Less than 1000 lumens - these are the lowest light output projectors available today, and they are typically the least expensive. For display of training videos and still photography in a darkened room, projectors in this category may be perfect for your needs. Keep in mind that the low light output means that you will want to make your presentations in a dark or dimly lit room so that the image on the screen is not washed out by ambient room light.
  • 1000 to 2000 lumens - this lumen range is a step up in performance and price. These machines are suitable for normal business conference room and classroom use. Presentations should be done with the room lighting reduced somewhat for best screen viewing. A completely dark room is usually not necessary.
  • 2000 to 3000 lumens - this represents the high-performance range of the portable and semi-portable projectors. Products in this class are suitable for large conference rooms and classrooms. They offer more flexibility in terms of ambient room light, since the image is bright enough that a reasonable amount of room light can be tolerated without washing out the image. They also offer more flexibility in terms of audience size, since they produce enough lumens to properly light a larger screen.
  • 3000 lumens and up - these ultra-bright projectors are in several performance classes unto themselves, ranging from 3000 lumens up to 12000 lumens or more. Prices of these products also cover a wide range depending on other performance characteristics. They are used in a variety of large venue applications, including board rooms, conference rooms, training rooms, auditoriums, churches, concerts, nightclubs, and so forth.

 

Key Features
 

Once you have your short list of projectors, you can narrow it further by checking the manufacturer's specifications and thinking about the following items:

Zoom lens: A zoom lens gives you the ability to set the projector at a convenient location, and adjust the projected image size. Many of the micro-portables have zoom lenses with limited range. A unit with a zoom factor of 1.2:1 will only let you adjust picture size by 20%. You can often move the projector a foot or two either way and accomplish the same adjustment. If you have a fixed screen size you are trying to fill, even a limited range zoom will make it easier to fine tune the image size to the screen. If you plan on projecting in many different environments, you may wish to invest in a projector with a more versatile zoom range, which will allow for more placement flexibility. Zoom lenses range from 1.1:1 up to 2.0:1 or more. The higher the number, the greater the zoom range.

Keystone Correction: In addition to the zoom lens feature, mobile users should consider the benefits of keystone correction. The keystone effect happens when you project an image from any angle other than straight onto the projection surface and results in an image that is not completely square. Most projectors now include a feature that corrects vertical keystone, which occurs when you are projecting downward or upward. Others go a step further and provide additional correction for horizontal keystone, which occurs when you are projecting from either side of the screen. Keep in mind that applying keystone correction typically results in a slight loss of detail and sharpness, but it can be invaluable when your projector cannot be set up perfectly square with the screen

Contrast: Contrast is the ratio between the brightest and darkest areas of the image. Contrast ratios should be high (1500:1 or higher) to get the best video or photo image. For computer graphics and data presentation, 400:1 is usually ample. However, room light substantially impacts contrast ratios by rendering blacks less black. With moderate room lighting, a projector with 400:1 contrast and one with 1500:1 contrast will look almost identical, all other factors being equal. If you are using your projector in a room with a good deal of ambient light, lumen output will be more important than contrast. However, in a darkened room, contrast will become more important for accurate display of graphics and video.

Video Signal Standards: Most business projectors accept composite video, S-video, and computer/RGB signals as three types of signal transmission. Most projectors also recognize YPbPr/YCbCr component video as well. However, there are two all-digital standards known as DVI and HDMI. Many new computer video cards feature DVI or HDMI output, which allow the user to keep the signal in the digital domain and eliminate analog to digital conversions. If you are interested in optimizing video performance and you have a video source that offers DVI or HDMI output, check to see which of the projectors on your list possess a digital input. The spec sheet may say HDMI, DVI-I, or DVI-D.

Multiple Computer Ports: If you want to connect multiple computers or video sources to the projector simultaneously, you will need multiple input jacks to accommodate this. For example, you may want to connect a notebook computer and a desktop computer to support two consecutive presentations, or two different presenters. If your projector only has one computer source, you'll have to unplug the notebook and plug in the desktop between presentations. Check to make sure the projector has enough connections to support your typical use.
 
Resolution
 

The amount of data that can be displayed on the screen at any given time is determined by a projector's resolution. Resolution is simply the number of pixels the projector uses to create the image. The more pixels it uses, the higher the resolution.

Resolution is usually quoted in two numbers, such as "1,024 x 768," where the first number refers to the number of pixels from side to side across the screen, and the second number refers to the number of pixels vertically from top to bottom.

Resolution can be quoted in other ways, as well. For example, 1,024 x 768 is also known as XGA, for eXtended Graphics Array. This terminology is primarily used for computer monitors, but extends to projectors as well. Since there is little rhyme or reason to this naming scheme, the only way to learn it is memorization. Common resolutions will be discussed later in this article.

When speaking of a projector's resolution, it is common to refer to "native" resolution. If a projector's native resolution is 1,024 x 768, that means that the actual number of physical pixels on the display is 1,024 pixels per horizontal row by 768 pixels per vertical column.

How much resolution do I need?

High resolution projectors are able to show more picture details than low resolution projectors. Since there are more pixels used to make the image, each individual pixel is smaller, so the pixels themselves become less visible on the screen. However, you will pay more for higher resolution.

Lower resolution projectors are much less expensive, and they can produce images that are just as bright and attractive as higher resolution machines. Unless you have a need to display fine detail, lower resolution products will be your best bet from a cost perspective.

Resolution options

Some basic choices for native resolution are the following:

  1. SVGA, or 800 x 600 - SVGA projectors are great for those on a tight budget, since prices have dropped dramatically in recent years. While most computers still output in higher resolution, SVGA can be a good option for powerpoint presentation or other applications that are not heavily dependent on detail.
  2. XGA, or 1,024 x 768 - XGA projectors have come down in price over the past few years, and have become the budget standard. Most computers still output in native XGA, so matching an XGA projector to your computer ensures you won't lose any detail.
  3. SXGA, or 1,280 x 1,024 - SXGA products are high resolution, and notably more expensive than XGA. These products are targeted for high end personal computer users and low end workstation users. They are used primarily for command and control, engineering and CAD/CAM applications where acute resolution of small details is important.
  4. SXGA+, or 1,400 x 1,050 - SXGA+ projectors are becoming more popular, and there are several offerings available in both budget and high-end configurations. SXGA+ resolution is useful for detailed photography and data graphics, but overkill for text display or Powerpoint presentations.
  5. UXGA, or 1,600 x 1,200 - UXGA is for very high resolution workstation applications that are detail or information intensive. These are expensive projectors that support a broad range of computer equipment. Relatively few products on the market have this native resolution.

Which resolution is right for you?

One of the key factors in choosing the right resolution is your typical application. Do you have a need for very accurate display of small visual details, or are you looking for a general presentation tool for text and small graphics?

If your primary use of the system is for Powerpoint presentations, pie charts, graphs, Excel spreadsheets, and general business display, you probably don't need to pay extra for very high resolution equipment. SVGA or XGA resolution projectors are perfect for this kind of work, and the best solution for the money.

If you are projecting engineering drawings, digital photography, or other images of a highly detailed or technical nature, you will probably need a projector of SXGA resolution or higher to produce an acceptable image for your purposes.

Matching your computer to your projector

Keep in mind that the best resolution for your projector is the resolution of the computer you intend to use with it. If you typically use a notebook computer with XGA resolution, you will want a projector with the same native XGA resolution in order to get the sharpest and cleanest image. Similarly, if you normally use a computer with higher than XGA output, such as SXGA+, you will get the best picture from a projector that has the same native resolution.

Projectors on the market today are capable of projecting input signals other than their native resolutions. For example, you can usually hook up an XGA computer to an older SVGA projector. The projector will automatically convert the incoming 1,024 x 768 signal to its native 800 x 600 output. However, there is always a loss of sharpness and detail in the process, so you will end up with a picture that is not as sharp or clear as if the incoming signal had been in the projector's native resolution.

This loss of sharpness also happens if you plug an XGA computer into a higher-resolution SXGA projector. You will usually get a decent image, but the conversion from 1,024 x 768 input to a 1,280 x 1,024 output will produce some softness that you may not appreciate after having spent the money for an SXGA projector. The loss in quality incurred by making a small resolution larger is generally less severe than that incurred by making a large resolution smaller.

The projector's process of converting a different input format to its native output format is called scaling. Making a small resolution large is known as upconversion, while making a large image small is known as compression. Some projectors are very good at scaling, so the resulting image softness is relatively minor, and quality degradation is almost negligible. The quality of scaling varies widely among projectors and like all technology, it is constantly being improved. Scaling is an important consideration, so whenever possible, try to see the projector demonstrated as you would use it.

Once you have determined which resolution most suits your needs, you can go to Find Projectors to find all projectors in that resolution class. The list will likely be very lengthy, but don't fret. We will be narrowing down this list shortly to better suit your needs.


Weight
 

Another consideration in selecting the ideal projector is its weight. If you are on the road a lot, you probably want the lightest, most portable machine available that still fits your resolution and brightness needs. 

If you travel occasionally, but want a bit more performance and are willing to carry a heavier unit to get it, take a close look at the projectors in the 7 to 10 pound weight range. As a class, these very portable projectors are brighter and more fully featured than the sub-7 pounders.

If you don't intend to travel with the projector, but still want the ability to move it around the office, from classroom to classroom, or to take it home on weekends, there are many excellent products in the 10 to 15 pound range that should be considered.

Finally, if you are going to use the projector in a specific place and have no need to move it around, weight is not an issue. So you should ignore it and make your selection on other cost and performance factors


  Projector Technology Explained
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