A projector's black level refers to the darkness of the black colors it can reflect. Not every black is the same. With this in mind, getting better black level performance out of your business projector means that you are making it easier to see details in dark areas of projected images. This is especially important when you are projecting video images, as opposed to computer slides, which typically have brighter colors and high levels of contrast.
Make your room as dark as possible. Look at your screen in your room's darkened state -- the color of the screen is the darkest color that your projector will be able to project. If you need to have some lighting, try to use directional lights that aim light directly on the area that needs to be lit, rather than lighting the entire room.
Select a screen with a black border, which makes viewers looking at the screen perceive more contrast. While this does not affect the projector's actual measurable black level performance, it will make the black levels look better to the human eye.
Engage your projector's "cinema" or "movie" mode. These modes typically reduce your projector's light output, but improve its black level performance in a darkened room.
Adjust your projector's brightness setting to its optimal level. To do this, project a widescreen DVD or other content that has black bars on the screen. Turn your projector's brightness control up all of the way, so that the bars become grey, then gradually turn it down until they become black. You want to stop at the point where turning the brightness control down more does not make the black bars any darker.
Optimize your projector's contrast setting. Put an image on screen with a broad range of brightness values -- preferably from pure white to pure black. Turn the contrast up so far that the lightest areas bleed into each other, then turn it down until the areas begin to differentiate from each other, stopping before the image gets darker without adding additional detail.