Front projection: A true home cinema experience
By The Vann’s Editorial Team
Last revised October 12th, 2009
There really is no limit these days as to how intricate and amazing you can make your home entertainment system. If you’re looking to really create a movie experience in your home, a home theater projector system may be the route for you. With a front projection television system, movies and sports become larger than life, and you really feel like you’re a part of the action. Front projectors and large screens often get overlooked when people are designing a home theater, but for spectacular home entertainment, they’re unrivaled.
This article will give you a rundown of the basic components of a front projection home theater system and what you need to consider when purchasing a system and designing your home theater.
Home theater room
A major advantage of front projection systems is the very large screen size you have at your disposal. As far as choosing the appropriate screen size for your viewing area, you’re really only limited by the properties of that area. Important properties to keep in mind are the size of your room, the amount of ambient light, and the viewing angle.
One of the most important considerations in determining the right screen size is the size of your viewing area — screen size and viewing-area space are closely related. In fact, the size of the image you want to display determines the distance you should sit from the screen, and, therefore, the distance your viewing area will allow you to sit from the screen plays a role in determining screen size. Generally, you multiply one of the screen’s dimensions (height, width, diagonal) by a fixed number to determine the best viewing distance. With high-resolution video reproduction, it’s common to see 1.5 to 3.5 times the screen width as the rule of thumb, with 2.5 times being optimal for Standard Definition content (like traditional non-HD broadcast television, VHS tapes, etc.). For example (reversing the math to calculate the appropriate screen size from a given viewing distance), if you plan on sitting ten feet from the screen, a screen between 35” and 48” would be ideal. Again, with High Definition, and especially 1080p, you can get even closer, so in the example above, you could easily opt for the larger screen. Of course, how far you prefer to sit from the screen is subjective. If you head to the front row of the movie theater when you go out, sitting close to your home theater screen may be just what you have in mind. The important thing is to make sure you have enough space in your home cinema room to accommodate a large screen, and still be able to sit back and enjoy the show.
Regarding ambient light conditions in your viewing area, projectors perform best in a darkened room, and a dedicated theater room is a natural home for a front projector. While there are specific screens that help overcome moderate to heavy ambient room light (see more, below), projectors perform their best in rooms where you can control the lighting.
Viewing angle is also an important consideration. If you have high ceilings, and are thinking about mounting your screen up high, you should be concerned about the viewing angle. “Half gain” is the standard that the projection screen industry uses to measure the brightness performance of a projection system when you are viewing the screen from an extreme angle. A projection screen’s peak brightness is seen when you are positioned directly in front of and perpendicular to the center of the screen. This is referred to as the “peak gain at zero degrees” viewing axis. As you move away from the center of the screen axis, the brightness of the image will begin to wane. The angle at which a brightness of 50 percent of the peak gain is reached determines the screen’s “half gain” (or half brightness) viewing angle specification. So if a screen’s half gain specification is 54 degrees, a viewer seated at 54 degrees from the center of the screen will observe half the brightness that a viewer seated directly in front of the screen will perceive. If you have high ceilings, you can solve this problem by pole-mounting the projector in order to place the lens at the same height as the top of the screen.
As a final note, when it comes to the size of your projected image, bigger isn’t always better. Projecting too large of an image may produce a picture with less than ideal brightness or noticeably visible pixel structure.
Using today’s LCD, DLP, D-ILA and SXRD technology (see the “Rear Projector Television” article for more details), projectors deliver terrific video reproduction while remaining portable. Also, they’re much more affordable and practical than CRT projectors. Projectors aren’t just for business presentations anymore. Manufacturers have adapted front projectors for home theater use, combining high resolution, high contrast ratios and terrific color reproduction for outstanding video reproduction.
A front projector’s raison d’etre is video reproduction. There’s no built-in screen, fancy speaker systems or TV tuners — it’s sole purpose is creating video images. You connect your components to the projector, and let it use its high-quality imager, optics and high-intensity lamp to work its video magic.
There isn’t a single projector that is best for every room and application, but there are a few important topics that will help you get a feel for how well a projector will perform. Resolution is one key factor. A display’s resolution is an indication of the number of pixels on the optical panel, and the greater the number of pixels, the greater the resolution and the better the overall image. A projector’s built-in scaler will up-convert or down-convert all incoming signals to its native resolution. HDTV-ready projectors are required to have a vertical resolution of at least 720 pixels.
A high contrast ratio is also a key ingredient for good images. The contrast ratio is the difference between the whitest white and the blackest black. A high contrast ratio makes it possible to display deeper blacks and more subtle color detail. Many projectors are equipped with multiple lamp settings that let you reduce brightness and boost contrast ratios for optimum viewing in a darkened room.
Rated in lumens, a projector’s light output is the third important factor in selecting the right model. All projectors will have plenty of brightness for watching movies in a darkened room. However, if you’re viewing content in a room where there’s more ambient light, you’ll want to have a projector with a brightness rating toward the higher end of the spectrum (ranges are often between 700 and 2500 lumens). You’ll also want a high brightness rating if you’re displaying an extra-large image, like one that’s 100 inches or larger. Unfortunately, there is no standard for measuring brightness (or contrast) so comparisons of products from different manufacturer’s won’t necessarily be accurate. However, comparing different products from the same manufacturer should give you a good indication of which offers the best performance.
The projection screen is as important as the projector in a two-piece projection system. As a matter of fact, it’s a good idea to research the types and sizes of screens available before purchasing a projector. Every home cinema application has unique characteristics that need to be taken into consideration when choosing the appropriate screen. Choosing the right screen will ensure your satisfaction with the system. There are a few different types of screens to choose from.
High gain curved screens consist of reflective foil surfaces mounted on large curved plastic backings. Although curved screens were mandatory several decades ago when video projectors offered much less light output than they do today, they are still a very popular option for use in rooms with high levels of ambient light. The reason concerns the physical properties of the curved surface itself. Because it is designed to direct the major portion of the projected image back into a reduced viewing cone, a high gain curved screen is equally adept at rejecting room lighting off to the sides. So if you design your room with lights and windows off to the sides and not directly opposite the screen, a curved screen will give you a brighter, higher contrast image than if you used a flat panel. If you anticipate having a substantial amount of light in the room from windows, inside lights, etc., a curved screen is the better option. Often, curved screens are the only solution for getting a high-quality front-projected image in a room with significant ambient light.
Front-projected fixed flat screens are one of the most common ways to view projected video images. In home theaters they are extremely popular because they closely resemble their counterparts in commercial theaters. Fixed flat screens typically consist of a vinyl screen material which is stretched across an extruded aluminum frame. These screens are not only very easy to install, they are quite affordable and are available in a variety of aspect rations, including 4:3 (standard) and 16:9 (widescreen). Keep in mind that flat screens are very sensitive to light in the room. If you can control the room lighting (i.e. with drapes, blinds and light dimmers) then flat screens are an excellent screen choice.
If you want your projection surface to retract when not in use, consider investing in a front-projected manual retractable screen. These screens operate similar to window shades. You pull them down for use and let them roll up when the show is over. Manual retractable screens are very affordable and are available in various aspect ratios.
Of course, if you want the luxury of automation, consider a front-projected motorized screen. These screens are powered by a 120 or 220 VAC power source and can be lowered and raised via a switch. Many home theater installers go a step further, and wire them to a relay that automatically lowers the screen when the system is turned on. Another control method is to interface the relay with an infrared controller so that the screen can be controlled via a hand-held remote control.
Tab-tensioned motorized rolldown screens sport external suspension cables that pull the screen surface taut, eliminating screen wrinkles and edge curl. Tab-tensioned screens are more expensive than their free-hanging counterparts but offer an extremely flat surface in a motorized housing. If you really want to go all out, you can get a trap door screen that actually mounts in your ceiling, making it invisible until the screen is rolled down.
A projection screen can offer lots of control when it comes to dealing with variable aspect ratios. This is because screens can be installed with electrically driven masking systems. Masking systems are black overlays that open and close to fit the actual image being projected. So no matter the aspect ratio you’re displaying, the masks can be set to create a perfect black frame around the projected image. With this type of system there are never any gray bars on the sides or black bars top and bottom — just the pure image in a solid black frame. This gives you the best overall visual presentation, and the maximum flexibility in handling all aspect ratios on the market.
Mounting your projector
As mentioned earlier, front projectors are portable. You could keep the projector in your closet and just pull it out for movie night, setting it on a table top. Of course, every time you want to watch a movie, you’d have to connect your DVD player (or DVR, or PC) to the projector, and run audio to your audio system.
A better option in the long run may be to ceiling-mount your projector. When mounting, the projector’s throw distance comes into play. A projector with a short throw distance doesn’t need as much room to give a large picture, which lets you mount it closer to the screen. This is good for smaller rooms. A longer throw distance means the projector will be mounted farther back in the room. This can be good for ceiling-mounting situations, with the projector mounted behind the viewing position. You’ll need to purchase a ceiling mount to complete the installation.
Most projectors have a feature called keystone correction, which helps you square up an image when the projector is mounted off-center. Although most models have at least vertical keystone correction, a few also have horizontal correction. This opens up your options somewhat when it comes to mounting your projector. However, when you use keystone correction, you sacrifice resolution, so you lose some image quality. Although keystone correction gives you a little leeway, it’s best to at least try and position your projector so that you don’t need to use this feature. The lens should be parallel to the screen so your image will be true, with straight edges on all sides. This isn’t always possible, and that’s where keystone correction comes in handy.
Getting it all connected
The ideal time for setting up your home cinema is when you’re building or remodeling your home, because then you can plan the wiring accordingly. Otherwise, an attic would be ideal for running the necessary cables. Don’t forget that you’ll need to have an outlet to power the projector. And you’ll need to run cables from your components (wherever they reside) to your projector. The ideal situation is to have an AV receiver with video switching, so you can get away with running fewer cables. It’s recommended that you run both HDMI and Component cables due to digital rights management issues, as well as a CAT 5E Networking cable for possible future use. You should also run an IR cable for an IR repeater to control the projector without having to aim the remote at the ceiling behind you. And, of course, you’ll need to run a power cable. Placing a tube between your component rack and the projector for the cables to run through provides a way to pull additional cables at a later time should standards for connection change. Most projectors are also equipped with component and S-Video/AV connections so they can accommodate most sources.
You can also run your video gaming system and your computer through your projector for some powerful multimedia entertainment. Whether you have permanent connections to this equipment from your projector is up to you, although gaming on such a large screen can be quite a powerful experience.
Run it all from your couch
To enjoy a true home cinema experience, you probably won’t want to be up running around the room turning equipment on and off, pulling down screens and adjusting volume. And you won’t want to have to turn around to point your projector’s remote at the unit if it’s mounted behind you. Pointing it at the screen won’t work depending on where your projector is mounted. There are, however, a couple of ways to take care of this.
You can purchase an IR box that you can place near the screen, with cables running to the projector and your stack of AV equipment that will let you control the system by simply pointing your remote at the screen and firing away. This provides a convenient way to comfortably run your system. RF remotes will also work with your system. They have the capability of sending signals through your walls, converting radio signals to infrared signals that your components will understand. This type of RF solution is subject to lag time, meaning that your components won’t respond immediately, and may create enough of a lag to be problematic. The safest solution is to run the wires and use IR repeaters if possible.
Of course, nowadays, there are remotes that can control about every function in your system. By programming these remotes you can even set them up to control the lighting in your house (with the right lighting components). With macro programming, you can connect different operations to work together. Imagine pressing the “play” button and watching your retractable screen come down as the lights slowly dim and your movie begins to play. Sounds like a pretty good home cinema experience, doesn’t it?
That’s all folks. The basics you need to keep in mind when designing your very own home cinema. If you have any questions whatsoever, please give us a call. We love this stuff, and we’re always happy to answer any questions. Our customer service representatives can be reached at 1-800-769-5668.