The six key things to think about when designing a front projection system
We at Acoustic Frontiers love to use projection systems. They are really the only way to get wide enough viewing angles to properly replicate the immersive cinematic experience in your home.
There are two main types of projection system:
Front projection. This is the type of setup used in 99% of theaters and is where the projector is in front of the screen.
Rear projection, where the projector is behind the screen. This type of design is used infrequently, typically when the viewing environment has high ambient light.
Putting together a front projection system is not as simple as just picking a projector and screen based on reviews. For best results it must be engineered.
This article discusses some of the key factors that must be taken into consideration when designing a front projection system. A future blog article will discuss rear projection systems.
1. Screen type is appropriately selected for the viewing environment.
. There are three main types of screens in usage today:
- White, non-acoustically transparent screens. We seldom use these unless doing a retrofit in an existing theater where the speakers are located outside of the screen boundary. Ideally these screens need fully light controlled environments with no windows or at least black out roller shades on all windows.
- White, acoustically transparent screens. These are our favorite type of screen as they allow the center speaker to be located behind the screen where it belongs
- Black, light rejecting screens. These screens reject light that hits the screen at off axis angles. They are great for use in rooms that have poor light control or where the client wants to keep some lights on during room usage. An example would be someone who likes to watch sporting events on their big screen. It is more fun and more practical to watch these events with ambient light on, especially when entertaining.
blog article for more information.
Projectors have two key variables which must be taken into account when laying out the system: throw ratio and lens shift. These metrics should be provided by the projector manufacturer.
Throw ratio typically quoted as a range - for example 1.82-2.48:1. Throw ratio together with screen width tells you the distance from the screen to mount the projector:
Screen width* x Throw ratio = Throw distance
blog article for more details on designing for luminance.
5. Viewing angles meet standards.
The angle subtended from each side of the screen to the seats in a home theater should meet industry standards. We prefer 45 degree or larger viewing angles for an experience that replicates a commercial cinema. See our blog article
for further details.
6. Room decor is neutral.
The interior decoration of a home theater should not negatively detract from the movie watching experience. The job of a screen is to reflect back light from the projector towards the viewer. This reflected light will strike nearby surfaces such as floor, ceiling and wall. If these surfaces are reflective then this light will then in turn be reflected back towards the viewer. In the worst cases a ghost of the onscreen image might be visible on the offending surface. Suffice to say that dark matte paint finishes or dark fabrics are obligatory for the best visual experience.
The other consideration is the wall to which the screen is mounted. For highest perceived dynamic range in the image this wall would be black. We like mounting our screens to baffle walls
, covering the front of these walls in a black acoustically transparent fabric.
Have we missed any important aspects of front projection system design? Please let us know via the comments below!
Need help engineering your home theater front projection system? Contact us now! Our favorite and most commonly used front projection brands are SIM2, JVC, Epson, Seymour Screen Excellence / Seymour AV and Screen Innovations.
About the author: Nyal Mellor
is founder of Acoustic Frontiers, a company specializing in the design, installation and calibration of high performance home theaters for enthusiasts