What’s in a Home Theater Projector?
Projectors vary widely in features, performance and price. Depending on your room and budget, some features will be more important to you than others.
The video projector is probably the most significant piece of any home theater. Without a projector, there would be no big screen, no wow factor and no friends jonesing for an invite to your house on movie night. Projectors, however, are also often misunderstood. They come in three basic technologies (LCD, DLP and LCoS), numerous sizes, and various prices.
As with most electronic products, price alone doesn’t dictate performance (it may give you an idea of quality or market placement). Some projectors can be easily installed by a DIYer, while others require professional installation and will produce professional results. When talking projectors with your home theater dealer, you’ll hear a lot of terms and technologies. Here we break down what goes into a projector and what features are important for different situations.
Light Engine. The light engine is the heart of the projector. There are three technologies currently in the market: LCD (liquid crystal display); DLP (Digital Light Processing); and LCoS( liquid crystal on silicon). LCD and LCoS projectors always use three separate imaging chips, while DLP may use one or three. Both JVC’s D-ILA and Sony’s SXRD are types of LCoS displays.
Lamp. The light engine requires a lamp. Most lamps can last between 2,000 to 4,000 hours. Lamps can be replaced, sometimes by the user; sometimes by a professional. A few projectors include two lamps that produce a much brighter picture. Some projectors are available with LED lamps. These produce very accurate colors, and the lamps last practically forever, but they can produce less light than traditional lamps, and the projectors are expensive.
Fan. All projectors with traditional lamps also include a fan to keep the internal temperature cool to protect the components from damage. Some projectors do a better job of insulating the sound of the fan than others. Iris. Like the iris of a human eye, a projector iris opens and closes to allow more or less light out of the lens. This can impact contrast and apparent black level, but some iris mechanisms move slower than others and the viewer can visibly see the change take place on the screen. With a good auto iris, this change will be undetectable to the viewer.
Focus. Like on a camera, a projector’s lens needs to be focused. Focus mechanisms can be either powered (operated by the remote) or manual. A manual lens can provide more precision of focus, but a powered focus is extremely convenient, particularly if the projector is mounted high or out of reach.
Zoom. A zoom lens on a projector works essentially the same as on a camera. Zooms can vary from 1.1:1 to 2:1. It makes the image smaller or larger on the screen to make installation easier. A wide zoom ratio is sometimes preferred, but full zoom can also reduce light output, so mounting a projector closer to the screen will yield a brighter picture.
Lens Shift. This feature allows you to physically move the position of the lens after the projector has already been mounted and allows the installer to correct for slight alignment errors without sacrificing any picture resolution. Better projectors include both vertical and horizontal lens shift.
Keystone Correction. This feature can be used to adjust for slight picture imperfections caused by improper alignment. Every projector includes keystone correction, but it’s a feature you should avoid using because applying keystone will sacrifice some image resolution.
Constant Height Memory. Many projectors now include a zoom memory to allow the image to easily switch between a standard 16:9 aspect ratio and a CinemaScope 2.35:1 aspect ratio. However, when the projector zooms forward to fill the wider screen, the image you’re seeing is not using all of your projector’s resolution. Depending on how large your screen is or how close you sit to it, this difference may be noticeable. Zooming may also reduce light output.
Inputs. In most installations these days, you really only use one input. If all video signals are being sorted through a processor, input selector or home theater receiver, then a single HDMI input will suffice. However, depending on how you plan to feed content from your sources to your projector, additional HDMI ports plus analog inputs are also useful. Nearly every projector on the market includes two HDMI ports plus component, S-Video and composite ports. RS-232 and IP (Ethernet) ports allow for easy integration with advanced control systems. A 12-volt trigger can be used for operating powered retractable screens or screen curtains.
ISF/THX Certification. Both of these certifications denote that a projector meets certain image quality requirements. ISF (Imaging Science Foundation) certification also indicates that a projector was designed to be professionally calibrated. An ISF-certified projector may include settings for different ambient light situations.
Built-in Speakers. Most true home theater projectors don’t include speakers because they don’t need them. You will provide separate speakers for the system. However, some projectors will offer lowoutput speakers for portable applications, such as a backyard movies.
Remote Control. The remote is, as you’d guess, the thing that turns the projector on and off or gets you into the setup menu. Most projector remotes are small and barely functional because the manufacturer expects that you’ll integrate the projector controls into a universal remote or control system. Still, I like a remote with backlit and dedicated buttons for each input or picture mode.
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