Why the right screen is so important to your theatre
by Alberto Vangi, with input from Paul Kutcher at Stewart Filmscreen
When looking at the role of products in an audiovisual system, none is more misunderstood than the projection screen. Far too often the screen is seen as a necessary accessory devoid of any technology, and as a product where any solution will do.
Nothing could be further from the truth. Sure, there are a multitude of cheap screens out there that simply employ off-the-roll materials without any form of engineered optical properties – just as there are cheap speakers assembled from non-descript components that no one would consider installing into their system. The role of the projection screen is to present a flat planar surface and direct the projected light back towards the viewing audience, while itself getting out of the way. A quality projection screen should act as a window to the world, be invisible to the viewer and not impart its own ‘personality’ onto the projected image.
Gain and colour
As with any form of technology, projection screens need a reference to be measured against, and with projection screens it is gain. The reference for gain is the chalky substance, magnesium carbonate. It is said to have a gain of 1.0 and is considered a full Lambertian diffuser – that is, any light that falls upon its surface will be diffused evenly in all directions off the surface.
When editing their movies during post-production and grading the footage so that the colours match from scene to scene, Hollywood studios require a screen surface that is totally neutral and doesn’t impart any artefact of its own onto the image. The majority of them use Stewart Filmscreen’s SnoMatte 100, a true unity gain 1.0 white surface that has long been recognised as the industry reference for image performance. Its optical coating imparts no sheen on the surface and it is utterly neutral in its performance.
Apart from using such a screen, the studios also employ a totally black room comprising of black walls, floors and ceilings, to ensure that there are no internal room reflections that will affect the image being worked upon.
It therefore goes to say that in an ideal world, to get the same image performance as a Hollywood studio, any projection room should be totally black, apart from the screen. In the real world, however, this is impractical – a totally black room is not only foreboding but is also aesthetically unappealing. So while most rooms can be darkened, they are typically not black enough to employ a unity-gain white screen, as there will usually be something in the room that will cause a glow or cross reflections. So to counter these, we need to look at surface options that will be less affected in these real-world environments.
Adding gain to a screen surface by employing optical elements makes the
screen more directional. So when we project upon the screen, more of the light is directed back into the viewing space and away from the side walls, thus reducing room cross reflections.
So a projection screen should be considered as part of a projection system rather than as a standalone product. When determining the most appropriate screen surface for any project a range of considerations need to be taken into account, including the intended screen size, projector being employed in the system, and room décor. Stewart Filmscreen offers nine front projection surface options, each engineered to provide optimal performance in a given environment. These include a range of white surfaceswith varying gains and similarly, a range of grey surfaces.
Watch this space
When watching a movie or television program in your theatre or media room, you are only looking at a single item: the screen. The screen is the final link in determining the quality of the image that you will view. Like speakers and power amplification, a projection screen is a product that is typically purchased once for a system. Unlike content delivery products that change on a regular basis due to technology changes, your projection screen will usually last the life-time of your theatre. So it makes good sense to invest a bit more in a product that is not only going to provide the optimal image quality, but will also last for the duration of the theatre.
Stewart Filmscreen have long been considered the reference for image quality for projection screens, manufacturing bespoke projection screens for more than 70 years for the very companies making the movies that you view at home. As the recipient of two Academy Awards for Technological Achievement for projection screen technology, a Stewart screen ensures you can view the movie as intended by the filmmaker.
With every product custom manufactured to specification, you can be sure that you are purchasing the most appropriate solution for your system.