Shed some light on the subject: 13 data projectors reviewed

		Contents Acer PD321 Benq PB2220 Canon LV-X4 Casio XJ-350 Epson EMP-745 Hitachi CP-X328W HP MP3222 InFocus LP120 Mitsubishi XD50U NEC LT245G Panasonic PT-LB10NTE Sharp XR-1X Viewsonic PJ551 Specifications How we tested Sample scenarios Editor's choice About RMIT

Put simply, projectors are becoming cheaper because vendors are moving more projectors. A relatively well-featured portable data projector can now be had for around AU$3500, whereas a year ago a similar unit would have been more than AU$5000.

A year ago the major players were utilising the traditional LCD panel projection technology; now more of them are using digital light processing (DLP). Another changing feature can be seen in the overall rated ANSI lumen output (lamp brightness) and contrast ratios. Most portable data projectors are able to produce approximately 1500 lumens; a short time ago, par was around the 800 to 1000 lumen mark.

Resolution is also a critical consideration. All the sub-AU$3000 projectors we looked at are SVGA (or 800 x 600 native), and while this may be acceptable for video playback, if you are seriously considering buying a projector for data projection then you need to ensure that you have a XGA unit. Many SVGA units are advertised as being "XGA capable", but this is a relatively rough-and-ready software interpolation that can end up making images looked distorted. So ensure you look at a minimum of true XGA (or 1024 x 768 native) resolution data projectors before investing.

Lamp technology
There are quite a few different types of lamps. The most common lamps used today are UHP (ultra-high performance) lamps. There are also metal halide (UHM), ultra-high energy (UHE), ultra-high brightness (UHB), video projection (VIP) and mercury arc (NSH). Lamp life hasn't really increased since the last time we tested data projectors -- you can still expect to get anywhere up to 2000 hours on average. Brightness does tend to drop off with many of them as they near their end of life. On the cost side, lamp prices have come down a little -- though it will still set you back around AU$700 to replace a lamp (compared to around AU$800 last year).

It's worth finding out what the warranty is on a replacement lamp. Some vendors won't give you any sort of warranty on a replacement lamp as they feel there are too many variables involved like individuals trying to install the lamp themselves. Even more staggering: some vendors might not give you any warranty on the original lamp as they see it as a consumable.

Screens
A good screen will also make your projector's image look far brighter and crisper than a wall. The way in which a surface refracts light is what differentiates one screen fabric from another. Most fabrics have ratings next to them which should help you chose an appropriate screen. When looking to buy a screen you should also choose one that's going to be appropriate in size taking into account the throw distance of the projector.

And if you're unlucky enough to have to cart around a screen you do have some options. There are portable screens that fold into compact cases and are ready to use in seconds. They are smaller, of course, but might be the way to go if portability is a big factor.