Whether you use a multimedia projector for business presentations in a conference room with a projection screen or to watch a movie on an ad hoc screen made from bed sheets or drywall, out-of-focus images reduce viewability. Unlike slide, overhead and opaque projectors -- which offer limited potential for image distortion because of their relatively simple analog mechanisms -- multimedia projectors combine mechanical and digital output, either of which can compromise image quality.
In some cases, blurry multimedia projection points to the way you set up the room in which you make your presentation, not to the projector itself. If you leave drapes, shades or blinds open, outdoor light competes with the onscreen image and can make it look blurry. Likewise, until you turn off overhead lighting, you can't assess the quality of onscreen projection. Before you assume you have technical problems, dim the room to the fullest extent possible and reassess image quality.
In some cases, blurry onscreen images result from nothing more sinister than a need for proper focus. Use a light touch on the adjustment ring, swiveling back and forth until you reach the point at which the image detail becomes clear. Some projectors include sharpness settings you can use to heighten the visibility of edge detail. Blurry projection also may point to smears or dirt on the lens or the condensation that can result if you attempt to use a projector in a warm room immediately after bringing it inside on a cold day.
When the projector points at the screen at any angle other than 90 degrees, image quality distorts. In these circumstances, parts of what you see on the screen may appear stretched at one edge, often the top or bottom, and out of focus because of the distortion. For the best image quality, set up the projector close to the screen and level with the center of the output surface. If the screen hangs at an angle because of the way its bottom edge anchors to a wall or other vertical surface, compensate by adjusting the angle of the projector. Some models include feet that raise or lower independently to adjust the projection angle. When you use something other than a regular screen as your projection target, any deviation from a flat vertical surface can cause distorted viewing.
Cabling and Resolution
Unless you can place your computer immediately beside the projector, you may need longer cabling to establish the data connection that provides input for your presentation. Avoid using cables longer than about 10 feet, or 3 meters, to maintain image quality without the degradation that occurs over long runs. Match your video projection resolution to the native output of the projector to maximize onscreen fidelity. Read the projector's user guide to verify the correct settings. If you find yourself faced with unfamiliar projection hardware, visit the manufacturer's website for a downloadable manual.