Buying a Projector

To make a decision on which projector you should buy, consider the following features:


BRIGHTNESS:
A key factor in the measurement of any projector's performance - normally indicated in ANSI lumens (American National Standards Institute measurement of "candle" power). Customers are advised to use caution when directly comparing models using this criteria as two models with the same quoted brightness may look quite different. Some models use LUX as a measure of brightness. Divide the LUX number by five to obtain the approximate ANSI lumen equivalent. Please use quoted figures as a guide only.

All manufacturers are fighting to increase the brightness of the projected image. Brightness is measured in terms of 'ANSI lumens' and the brightest machines command a premium price. Projectors in the range 250-400 lumens are best used away from direct daylight and with no office lighting. Units in the range 400-800 lumens can be used in most office condition away from direct sunlight. Units above 800 lumens are ideal for larger offices and conference rooms. No projector can really compete against direct sunlight!

Contrast attracts less attention but is important. Contrast measures the difference in light intensity between the dark and light areas of the screen. A high contrast figure is best; typically data projectors work in the range 150 to 300.

RESOLUTION / SIZE:
The number of pixels of information that make up an image. The more pixels - the higher the resolution - and the better the image quality. LCD devices have a single fixed "true" resolution but may accommodate other resolutions using in-built compression or expansion technology. Established standards are:

• VGA (Video Graphics Array): 640 x 480 pixels S (Super) VGA: 800 x 600 pixels, Windows 95 compatible and the most popular. XGA: 1024 x 768 pixels and above SXGA: 1280 x 1024 pixels, suitable for today's most popular workstations like those from SGI, Sun, DEC etc. The sharpness and clarity of the image is determined by display resolution. The resolution of a display is given in terms of columns and rows of pixels making up the picture.



• SVGA or 'Super VGA' resolution is most popular and features 800 columns by 600 rows. SVGA is the resolution of most existing laptop computers and is fine for most PowerPoint type presentations. Whilst not essential it is a good idea to match the native resolution of the projector to that of the computer used to drive it.



• XGA (1024 x 768) is becoming increasingly popular as this is also becoming the norm for newly introduced laptops. There has also been a significant reduction in the price of XGA projectors. These units give a sharper image and are valuable for projecting more detailed images, smaller text etc.

Higher resolution SXGA units are available but in the main are reserved for specialist applications.

CONTROLS:
Normally there are a set of controls on the projector itself, with most being duplicated on an infra-red handheld remote. The controls would normally allow adjustment of brightness, contrast, colour tint, source (data or video), volume and image orientation. Zoom and focus controls can be controlled in a similar fashion or they may be manually adjusted using rings on the front of the projector.

In addition to controlling the projector, most handheld remotes are designed to control the computer by simulating the actions of the mouse. This is particularly useful when moving through a PowerPoint presentation a slide at a time. Using the remote mouse to navigate the more detailed menu operations can be cumbersome and it may be best to resort back to the keyboard!

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

• Zoom lens:
  If you are using your projector for mobile applications, a zoom lens can be very handy. It gives you the ability to set the projector at a convenient location, and adjust the projected image size. Without a zoom lens, the only way to adjust the picture size is move the projector forward or back. A note of caution though--many of the micro-portables have zoom lenses with limited range. A unit with a zoom factor of 1.2x 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. Nevertheless, 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.



• Contrast:
  Contrast is the ratio between the brightest and darkest areas of the image. Contrast ratios should be high (400:1 or higher) to get the best video image or the most legible computer/graphics image. Room light substantially impacts contrast ratios. If you intend to use your projector with the lights on, consider projectors with very high contrast ratios.



• Rear Projection Capability:
  If you want to set up your projector to shoot from behind a screen, it needs to have the ability to reverse the image so that it looks right on the screen. Most projectors have this feature today, but if you need it, you can eliminate any projector that doesn’t have this capability from your short list.



• Video Format Compatibility:
  The standard video formats are NTSC, PAL, and SECAM. Many projectors accept all three, but if you'll be playing video from Europe, pay special attention to whether the projector you're considering can accept PAL and SECAM formats.



• Video Signal Standards:
  Most video devices accept composite and S-video as two types of signal transmission. Almost all projectors will accept both inputs. However, there is a new standard known as component video. Some of the new DVD players offer a component video output signal in addition to composite and S-video. You will also be able to get component video signals from some satellite systems. Televisions and projectors that are equipped to handle the component video signal will produce a superior video image than those which cannot. If you are interested in optimizing video performance and you have a video source that offers component video output, check to see which of the projectors on your list are capable of accepting a component video signal. The spec sheet may say component video, or alternatively (Y, R-Y, B-Y) or YPbPr.



• Ceiling Mountable:
  If you want to mount your projector on the ceiling, it will need the capability to project the image upside down. The large majority of projectors will do this today, but verify that this feature exists. Also, you must verify that a ceiling mount exists as an option for this product.



• Universal Power Supply:
  Universal power supply means the projector will automatically detect different voltage levels, such as 110 volts in the United States or 220 volts in Europe, and adapt easily to them both. If you plan to travel with your projector in countries with different power systems, this is a must.



• 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 speakers. Check to make sure the projector has enough connections to support your typical use.



• Data Signal Ports:
  Most importantly, make sure the projector you choose supports the computers you intend to use now and in the near future. This is a significant investment and the pace of change in the computer industry should be a consideration. PC and PC compatibles are nearly always supported with a direct connection, but Macintosh may be a separate connector or require an adaptor. If you are using a workstation, check that the models you intend to use are supported in the manner you intend to use them and if adaptors are needed, know whether they are included or an additional cost item.

For more information on projectors visit www.avstore.com