Projector FAQs
What is a lumen?
The ANSI lumen was created by the American National Standards Institute as a standard way to measure projector brightness.
How bright should a projector be?
One primary factor when considering brightness is the size of the room. For small conference rooms or offices, 1,000–1,500 lumens will usually work fine. For medium-sized conference rooms or training rooms, you may want to choose a projector with 2,000–3,000 lumens. For larger venues, such as auditoriums and house of worship facilities that can hold more that 150 people, consider 3,500 lumens as the minimum brightness.
Ambient light will play one of the largest factors when considering projector brightness. The projector cannot make the screen appear any darker than it already is. The gray screen that you see when the projector is turned off is the highest level of black you will be able to show in the image. Bright high-lumen projectors flood the image with such bright white light that the gray screen you see appears darker than it truly is. If you have a brightly lit room in which the lighting cannot be dimmed, add 1,000 lumens. For instance, in a small conference room or office with, bright ambient light, where a 1,000–1,500 lumens projector may have been suitable, you may want to increase to 2,000–2,500 lumens.
What is peak lamp life?
LCD projectors generally use a metal halide source. The lamps offer a very white light and a life of 750–4,000 hours or more and typically give plenty of warning when it is time for a replacement. Lamps normally do not burn out, but gradually grow dimmer over time. Total lamp life is not always a useful measurement because the lamp will function long after it is too dim to effectively use. For this reason, manufacturers offer a peak rating and a peak lamp life. This is the time the lamp will last at 80-percent to 90-percent of total brightness.
How do I extend projector lamp life?
There are many factors that contribute to lamp life of a projector. They include installation, intake of cool air and exhaust of hot air, usage and proper maintenance. The build up of heat can reduce lamp life and damage the projector. There are a few things that can be done to extend projector lamp life. Before turning off the projector, wait at least five minutes to allow the fan to properly cool the unit. Do not obstruct the air intake or exhaust vent. Keep the exhaust vent at least two feet from any object. Run your projector for two weeks and/or 20 hours shortly after your purchase to protect against initial lamp failure. Based on the environment, cleaning the projector's air intake filter every three to six months will also extend the life of the projector.
What is contrast ratio?
The contrast ratio is a measurement in the difference between the white and black pixels. The greater the contrast ratio, the better able the projector is at showing subtle details and tolerating ambient light. There are two common ways to measure the contrast ratio. The contrast ratio can be determined by measuring the light output from an all white image (full on) and an all black image (full off). This is the full on/off contrast ratio. The ANSI contrast is measured with a pattern of black and white rectangles. Be careful when comparing contrast ratios as the ANSI contrast ratio will always be a smaller number than the full on/off ratio.
What is keystone correction?
Keystone correction is the term used to correct image distortion caused by the projector not being perpendicular to the screen. The sides of the image will distort and become different widths. Most projectors will have a degree rating to which the image can be corrected.
What is lens shift?<br/>
When projectors are equipped with lens shift, the optical lens can be physically shifted vertically and horizontally. Vertical lens shifting is the most common type of shift used because it allows for keystone correction and assists in aligning images when multiple projectors are stacked on top of one another.