Where projectors are concerned, 'portable' used to mean anything with a carry case - and often such cases were effectively large suitcases - but the last few years have seen dimensions shrink while brightness and feature counts increase. NEC's latest foray into this market is represented by the LT155.

With dimensions that give it a footprint smaller than a sheet of A4 paper, this projector is one of the most portable on the market. It weighs in at 2.2kg, about the same as a small-ish notebook computer, and comes with a fairly sturdy carry case that can be easily slung over the shoulder without risk of muscle strain.

The LT155 is pretty easy to set up and use. There's an adjustable foot at the front to raise or lower the projected image, while focus and zoom functions are controlled by twisting the lens mount or its surround. Ports at the side of the unit allow you to attach the usual D-sub VGA graphics input from a PC, as you'd expect, but there are other connections too, such as composite video and S-video ports (to display film or video footage), plus an audio input and a PC Card (PCMCIA) adapter (to display presentations that have been stored on memory cards).

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As far as technical specifications are concerned, this is quite a powerful little machine. It has a brightness rating of 1200 ANSI Lumens, which should be plenty for office work, and the display is crisp and well defined. Brightness is always a concern with projectors, as they are increasingly used in well-lit offices, but the LT155 coped well in our tests. The native resolution of 1024 x 768 will be enough for most purposes, but higher resolution inputs (up to 1600 x 1200) can be displayed via a pixel compression algorithm. You lose a bit of detail, but otherwise this feature works reasonably well.

All projectors make a noise, because of the fan that's required to dissipate the heat generated by the lamp. This one is no exception, but there are two fans in place of one, which helps keep the noise down when the unit is idle or when it's in 'Eco' rather than 'Bright' mode. And even on full power, the LT155 is not exceptionally intrusive.

Using the supplied remote control - which has a built-in laser pointer (imagine our excitement) - or alternatively the menu buttons on the top of the projector itself, you can access the comprehensive 'on-screen' menu, which has corrections for keystone, colour temperature, gamma correction, and various other functions, much like those of a conventional monitor. The keystone option is particularly welcome, given that projectors are usually pointed slightly upwards when in use, so the image is distorted accordingly. This feature helps to overcome that distortion.

Various tweaks can be applied to video sources too, and there's a digital zoom option so you can zoom into an image using the remote control; to highlight a particular feature of a graph, for example. Conveniently, there's online help too, which saves a lot of time since you can quickly scroll through to the information you need without even switching on the host PC.

Portable projectors aren't exactly the most important item on everybody's IT shopping list, but they are very relevant to travelling sales people and anyone else who needs to give presentations in situ. This projector is small, light and powerful, and has a good selection of inputs and features. But four thousand pounds is a lot for any company to pay to equip even its top sales person with an LT155. NEC is not alone in its pricing strategy, so we must assume that it still costs a lot to build these machines, but until prices come down, portable projectors will remain a rare sight.