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A Buying Guide

To make a decision on which projector you should consider the following features of the projectors in our catalogue.

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 - we are always pleased to demonstrate products to ascertain their suitability.

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. Projecters in the range 400-800 lumens are best used away from direct daylight and with no office lighting. Units in the range 800-1200 lumens can be used in most office condition away from direct sunlight. Units above 1200 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 projecters work in the range 150 to 3000.

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.

XGA resolution is most popular and features 1024 columns by 768 rows. XGA 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. There has also been a significant reduction in the price of XGA projecters.

SXGA (1280 x 1024) is becoming increasingly popular as this is also becoming the norm for newly introduced laptops. 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 projecter.

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!