Berlin  - Presentations require technology. It's tough to bring across the sizzle to your audience through simple slides or self-coloured paper handouts.

PowerPoint and similar programs make it so easy to create multimedia presentations that it's often more difficult to forego digitalisation than to simply go with the flow. The one key factor is a suitable projector. When looking to buy a projection unit, the experts recommend that the price not be the only crucial factor.

"I've yet to see a projector for under 1,500 dollars that was worth recommending," says Peter Knaak from the German consumer testing organization Stiftung Warentest in Berlin. From that price up to around 2,000 dollars there are a number of devices that are quite good, Knaak says. While a variety of projectors are available for several hundred dollars nowadays, they are suited only for video presentations in completely darkened rooms - if even that.

For business users, however, both the projection contrast and brightness values must meet certain standards. "The most important thing for presentations is the lighting power," says Knaak.

Brightness for projectors is listed in ANSI lumens, which describes a physical unit of the light beam. Matthias Hemesath from beamershop24, a German based projector portal, recommends that users requiring normal presentations find a model with XGA resolution and a high brightness value of 2000 to 2500 lumens.

In practice, however, the projectors often fail to live up to the nominal lumen values stated by the manufacturers, explains Jan-Keno Janssen from Hanover-based c't magazine. Even if the manufacturer claims 2,500 lumens, it's possible that the device will only achieve 1500 or so. "The only remedy is checking out test reports ahead of time," says Janssen.

Real life does not always allow for the darkening of rooms for presentations, however, such as in situations where the audience wants to take notes, or where the speaker wants to read prepared comments. That's why image resolution is crucial too.

"The projector should provide at least XGA resolution, which is standard," Janssen says. "HDTV is even better. The very cheap models offer only SVGA," Janssen says. Lighting power and resolution are indeed two important aspects in the selection of a projector. The type of beaming technology is another: DLP and LCD. DLP projectors use a rotating colour wheel to produce multicoloured images. The disadvantage of that technology is that many people perceive rainbow colouration when a quick image switch is made from light to dark. When compared to LCD technology, DLP projectors offer better black and white contrast and improved brightness. It's a good idea to review both technologies in person.

Beyond rainbow effects, the noise level of the running projector can also be a disruption, Peter Knaak says. "We found huge differences in the fan noise levels," Knaak says. That is yet another reason for consumers to test out a device before making a purchase. "It's also important to check how far the projector has to be from the screen to produce a good image," says Knaak. Devices should be able to create a two-metre sized image at only 75 centimetres distance from the surface.

Another area of great variety is the size and weight of the machines. "You have to decide on your own here how important the handiness of the device is for you," Knaak says. Projector expert Janssen also recommends reviewing the manufacturer's guarantee. Some companies only offer a 90 day guarantee on the lamp. "That's very short. Those lamps cost hundreds of dollars," he says. The guarantee should not be shorter than six months at the least, he recommends.

It's also possible to rent out the devices for the occasional presentation. When asked for this service, Matthias Hemesath of beamershop24 queries his customers about how precisely they'll be using the device. "It makes a difference if you want to watch a DVD with the projector or if it is going to be used for a business presentation" Hemesath says.

Home theatre beamers require a high contrast level. The space must also be absolutely dark. "The devices should be as quiet as possible, which also means enormously big and heavy," says Hemesath. The LCD technology variant is better for depicting photos, Hemesath notes, because it offers better colour fidelity. The DLP technology offers a better contrast ratio, however. The various rental companies will ship their devices for around 50 dollars per day. (dpa)