Digital projector specifications always include values for brightness and contrast. While there are many factors that determine the best projector for an application, knowing the brightness and contrast may quickly qualify the projector, or not, for it’s intended use.
Brightness is projector light output measured in lumens - the higher the lumens, the brighter the projector. Generally, projector prices go up as lumen output increases.
Contrast is presented as a ratio between the brightest and darkest areas of a projected image.
Projector light output ranges from less than 100 lumens to more than 10,000 lumens.
Projectors can be roughly categorized as follows by brightness levels:
- Up to 2000 Lumens – usually portable projectors designed for small group presentations in spaces that can be darkened to overcome the relatively low lumen output.
- 2000 to 3000 Lumens – these projectors may still be portable but with a step up in brightness they will be suitable for standard conference rooms and classrooms. At this light output, some ambient light is usually acceptable.
- 3000 to 4500 Lumens – these high performance projectors mean they can be used in larger spaces, project bigger image sizes and function well even with moderate levels of ambient light.
- 4500 Lumens and higher – these very high brightness, ultra high performance projectors are designed for use in the largest classrooms, boardrooms, churches and auditoriums. For demanding applications such as these, this class of projector, with the highest brightness levels, may be required.
The amount of brightness you need should be carefully considered; more lumens is not always better. If your application does not require high brightness, you can save money on your projector purchase.
Here are several questions to answer that will help determine how bright your projector needs to be.
1 – If the projector will be used in the same space most of the time, how dark can this space be? If the answer is completely dark, then you will be able to get by with a lower brightness projector for most applications. However, if the projector will be used for training or teaching, some ambient room light will be necessary for Q&A and note taking. This type of application will require higher brightness projectors.
2 – Does the space have a projection screen? If yes, the reflective qualities of the screen will allow lower lumen output projectors to present clear images. If the projector will be used in multiple spaces, some without a screen, then the better choice is a higher brightness projector.
3 – What is the typical size of the projected image? In large spaces with many viewers, image size will need to be large enough to make it easy for everyone to see, including those in the last row of seats. As image size increases, the perception of image brightness diminishes. Larger images require higher lumen output projectors to maintain a viewer’s perception of sufficient brightness.
A contrast ratio of 1200:1 will likely display images with higher contrast than a projector with a ratio of 600:1. I say likely because contrast ratios assume ideal projection conditions and represent a theoretical rather than measured value.
The contrast level seen by viewers is highly dependent on the level of ambient light in the room. A room with any ambient light will reduce the visible contrast on the screen. Moderate amounts of ambient light may completely wash out any difference in image contrast between projectors with 1200:1 and 600:1 contrast ratio specifications.
If you intend to use your projector for graphic display or videos, strong contrast will improve the experience for viewers. The overall effectiveness will depend both on the contrast ratio of the projector and the ability to completely darken the room.
Bottom line, the relative importance of brightness versus contrast primarily depends on the intended use of the projector and ability to control ambient light in the space it will be used.
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