Start out by asking yourself where the projector is going to be used and how much ambient light is in the room? How many people do you expect to be viewing, and what sort of screen do you expect to be using? Other issues may include weight, cost and what particular applications you expect to use the projector for.

The first thing to consider is where the projector will be used. A room designed to hold a large number of people will require a larger projected image than a smaller more intimate room. Increasing the size of the image will diminish the brightness of the projection so a brighter more powerful unit will be essential

The amount of light in the room is a critical factor when it comes to producing a viewable image. A room with a large amount of ambient light will demand a much brighter projector. Ideally the room should be completely dark but in the main this simply isn't practical. We have to accept that most rooms will be dimly lit to safeguard against accidents and to provide enough light for the presenter to make eye contact with their audience.

Adjustable room light levels may offer a compromise. Dimmer switches on the lighting controls or adjustable window blinds can provide a good degree of lighting flexibility and will allow participants to take notes and still get a good view of the material on screen. It is worth remembering that a room with lighting that can't be dimmed or where sunlight may strike the projected image will demand a very bright projector.

The surface on which you propose to project your presentation material can have a marked effect on image quality. Many meeting rooms simply offer a painted white wall as a projection screen but walls are a very poor reflector of light. A good quality projection screen will reflect more light back to the audience because it is made using materials that either focus or diffuse the light shining on it and will control how light is reflected back to the viewer.

The final consideration is how you plan to use the projector. If you intend to use the projector for training sessions then remember that these are usually conducted in a well lit room to allow for note taking. Showing videos or delivering presentations to an audience can be carried out in a dimmed room. Each application's projector requirement is very different.

If you plan to use your projector for a number of different uses then make sure you have identified the most 'light hungry' venue and make your choice of projector accordingly. Just remember that projectors come in a wide range of light outputs. A bright powerful projector offers more versatility but, in the main, the brighter the projector, the more it costs.