September 27, 2012
| by Grant Clauser
We talk a lot about projectors for home theaters—how bright they are or what kind of contrast ratio they offer, but the projector is just the device that delivers the light. There are other factors that help ultimately determine the picture experience, including the screen, ambient lighting and room characteristics. Here are some basic guidelines for dealing with light in your theater or media room.
The material you aim your projector at plays a big role in the image, but choosing a screen isn’t always simple. There isn’t one screen that will work for every situation. The truth is that screens will behave differently in different circumstances, so you have to carefully consider what your room needs and what you want out of it when selecting a screen.
Eric Haas, technical specialist at Current Concepts in Coopersburg PA says he recommends screens on a case-by-case basis. “We take into account the screen gain, the light output of the projector and the ambient light in the room,” he says.
For rooms with a lot of ambient light, he’s installed screens with a light rejection surface (also called angular rejection), which can work very well, but there may be situations where even that doesn’t solve all problems. For instance, light rejecting screens are designed to turn away light at very specific angles while accepting light that comes from the direction of the projector. In one home, he found that light coming in through a window in the back of the room was hitting the screen at just the right angle that the screen essentially treated it as if the light was coming from the projector, while light from other parts of the room didn’t create a problem.
There isn’t an all-around best screen—one that works perfectly in all situations—but some basic guidelines can help you get the one that will work best, most of the time, in your room. “We were founded on the principle that there is a perfect screen for every application,” says Dave McFarland of Stewart Filmscreen. Finding that screen is a matter of evaluating the room’s variables, the projector and your expectations (and budget). However, to make selection easier people, Stewart recently launched a new brand of screens called Cima, which includes two materials: Neve, a while material with a wide viewing cone appropriate for light-controlled rooms; and Tiburon, a gray screen meant to boost black level in rooms with more ambient light.
David Rogers of Elite Screens agrees that screens which selectively reject light can work very well in “light infested” rooms because the screen’s reflective under layer only returns light coming from the direction of the projector. The downside is those screens may have a narrow viewing cone.
Sometimes, Haas says, a very high-gain screen can be a good option in an ambient light situation, but not all high-gain screens are good at rejecting ambient light or reproducing strong contrast. A high-gain screen can also help boost the performance of a dimmer, less-expensive projector.
Stewart suggests that users should also be aware of lens ratio when selecting a screen, because it can impact uniformity and hot spotting. The company recommends that screen gain should never be greater than the lens ratio.
Harry Blanchard, of Hi Fi House in Broomall, PA, first looks at the shape and size of the room, when recommending a screen. A wide room he says, will require a screen that allows for a wide viewing cone. Some screens will focus their reflected images in a narrow cone toward viewers directly in front, while others cast a wider image. When looking at screen specs, look for the half gain number. The larger the number, the larger the viewing cone before the brightness drops by half from peak brightness. The shape of your room and spacing of your seats can determine what screen works best in your room. Because projection screens in dedicated home theaters tend to be big, often filling up most of the wall, this doesn’t tend to be an issue in a lot of rooms (but it is a big deal for flat panel TVs). Some high gain screens can focus the image in a narrower angle.
Blanchard notes he turns to a Stewart Studiotek 130 screen (a matte white 1.3 gain screen), but if excess ambient light is an issue, then a high-contrast or angular reflective screen is preferred.
When looking at light rejecting screens, it’s important to know that most screens only reject light from one plane. Screen Innovations’ Black Diamond material, says SI director of sales Blake Vackar, is the only one that rejects light from both the horizontal and vertical planes. This means that light from side windows and a white ceiling are both turned away from the picture, reducing light scatter by 75 percent. It does this by incorporating eight optical layers over a highly reflective surface. The curious part about the Black Diamond (particularly the 4k .8 material) is the screen material is black, but when you shine a projector on it, you get vibrant colors, real whites and deep blacks. That screen does have a fairly narrow viewing cone of 45 degrees to half gain , so this makes it appropriate for a dedicated theater with seating all grouped in the ideal viewing area. For a wider room, SI offers a 1.4 grain dark gray screen with a wider viewing angle and most of the contrast benefit of the black screen.
Vackar notes that a wider viewing cone can be important for media rooms, especially for video gaming, because gamers may be situated all around a room. Black Diamond screens come in a Zero Edge format that looks better in multi-purpose rooms.
Another option for battling extreme light situations is to use two projectors in a system such as Elite Screen’s AirFlex5D system which stacks two projectors into one housing and uses a processor to keep them in sync. Such as system can deliver double the light output of a single project, but can cost less than buying an ultra-bright projector.
Draper recently added a screen selector tool on the company’s web site. You can check that out here. Most other screen companies offer similar tools, but if they don’t any home theater dealer/installer will be able to walk you through identifying the same variables to help you decide.
Grant Clauser has been covering home electronics for more than 10 years with editorial roles in several consumer and trade magazines. He's done ISF-level damage to hundreds of reviewed products and has had audio training from Home Acoustics Alliance and Sencore. He's also the author of the book The Trouble with Rivers
. Follow him on Twitter @geclauser.