Projection Screen Selection

Selecting the right projection screen ensures that you do not waste the investment you have made in your projector. There are a lot of choices available in screen design and sizes for matching your viewing situation which might be a home theatre, training room, boardroom or lecture theatre.

Projection Screen Size

Screen size is determined by numerous factors such as room size and layout, ceiling height, seating arrangements, ambient light level (and control of) and visual acuity, all of which also, influence projector selection and positioning. Ideally, screen size should be determined as part of the process of deciding on the right projector.

Projection Screen Type

Common types of projection screens including portable, fixed or pull down.

Portable (mobile) screen

Portable (mobile) screens can be of a lift-up or pull-down from a floor box or tripod and are designed to be light for easy handling and transport.

Pull down (roller) screen – motorized or manual

A roller or pull down screen is a good general use screen and has the advantage that it can be stored away when not in use. Roller screens can be operated manually (pulled down), or motorised (remote control). They are suitable for wall or ceiling mounted options, or above the ceiling with additional components added in. The disadvantage of roller screens is that the material may become stretched with use over time. Moving parts and continual use can result in a piece of equipment that experiences wear and tear and may need parts replaced.

Fixed (framed) screen

Fixed or framed screens are better for dedicated viewing areas. Depending on surface materials, a fixed screen is often a less expensive, more durable option. With less movement fixed screens have less chance of stretching over time. Fixed screens can be mounted or suspended .

Generally fixed screens are the optimum choice for best results as the screen material is stably supported and unlikely to stretch and become wavy. Motorized screens place no stress (stretching) to the screen during lowering. Side wire tensioned models are a good option. Manual pull-down or pull up screens stretch (tension) the screen material which can cause screen surface distortion over time. Portable screens are the least stably supported and most likely to have screen surface distortions.

Projection Screen Aspect Ratio

A screen should be able to handle the dimensions of all the different sizes of projected images which are likely to be displayed on it. Video from different sources have different aspect ratios. Aspect ratio is the ratio of an image’s (projected or otherwise) horizontal to vertical measurements expressed as x:y. Some of the common aspect ratios are:

Standard definition television (NTSC or PAL) – 1.33:1 (4:3)

High Definition Television (HDTV*) – 1.78:1 (16:9)

Widescreen movies – 1.85 to 2.35:1

* The international standard format of HDTV as used in Australia, Japan and America, as well as in Europe on satellite and non-HD widescreen television (EDTV) PAL-plus is 16:9. Many digital video cameras have a 16:9 recording capability.

Projection Screen Types

Screen type is influenced by projector positioning as not all screen types are suitable for all projector positioning options. If your projector is ceiling mounted, for instance, you need to use a diffusion style screen (light is reflected in all directions evenly) or a reflective style screen (increased reflective properties for high ambient light levels or low brightness projectors). A retroreflective screen (reflect light primarily back towards the projector), on the other hand, is suitable only for projectors that are mounted at table (seating) height.

Screens can come with a black screen border (masking border) which can enhance the perceived brightness and contrast of the projected image. This is because the human eye will compare the projected image with the black border rather than white edges beyond the edge of the projected image. A screen border also avoids image bleed-off for a more professional look.

Drop is extra fabric added to the top or bottom of the screen to adjust the screen surface to within normal viewing heights. The normal line of sight for someone sitting is about 15 degrees below horizontal and the comfortable range of head tilt is 30 degrees from level (any seat tilt must be taken into account)*. Extra drop can be either black or white. This type of customization, which makes it impossible to return the screen, is one reason why it’s best to select your projection screen after the projector has been decided on.

* Cinemasource Seating Guide

Projection Screen Surface Materials

Front projection screens are available in a variety of materials which manufacturers specify in terms of gain and viewing angle. Material selection depends on projector brightness (screen gain) and seating arrangement (viewing angle).

Gain is a measure of a screens reflectivity with the measurement being perpendicular to the screen. The reflectivity is measured in comparison with a standard reflective surface (magnesium carbonate) so gains over 1.0 do not mean that the screen is boosting the brightness of the projected image falling on the screen.

Viewing angle is maximum angle from the perpendicular centreline of the screen at which the picture quality is still acceptable (brightness adequate).

One influencing factor of what gain is needed from the projection screen is the luminance level of the projected image.

Projected Image Luminance level (foot-Lamberts) = brightness of projector (ANSI lumens) / area of screen (ft squared)

If the projected image brightness is low because of a low brightness (lumen) projector then a reflective style screen may need to be considered. There are numerous guides to what an acceptable lumenence level measured off the screen (reflected luminance).

SMPTE (Society of Motion Pictures and Television Engineers) standard SMPTE 431-1 for screen luminance recommends, for a darkened viewing environment, a screen luminance of 14 foot-Lamberts (48 candela per m2 or 48 nits) measured at the centre of the screen. This is a minimum level however, and projector manufacturer Projection Design for example nominates that most theatres are typically in the 25 – 35 foot-Lambert range. See Screen Recommendations.

Screen Materials

matte white (gain = 1.0, viewing angle = 60 degrees) provides good all round performance for color reproduction, resolution and viewing angle. It is a popular choice for business applications.

gray (gain = 0.8 – 1.2) can have a slightly lower gain but, is popular for home theatres (lower ambient light viewing) as it enhances both contrast and black levels which are important factors in determining picture quality.

high contrast white (gain 1.3 – 2.5) which is optimized for high gain and are a better option for viewing environments which have some ambient light or projector with low brightness.

higher gain screens with less contrast performance help when ambient light is a serious problem for the projector brightness (lumens). A problem with high gain screens is that being more mirror like they can have a brightness hot spot where the projector lens is reflected. Higher gain screens also have a narrower usable viewing angle which means that there is a rapid drop off of reflected light away from the centreline of the projection screen.

curved screens (higher gain) avoid the hot spot problem of high gain flat screens as the entire screen is a hot spot and therefore delivers even brightness.

Higher gain projection screens can be used to improve projected image brightness if the projector brightness is low for the ambient light in the viewing environment. Beside cost it is necessary to check if there is a compromise for the extra brightness which may come in the form of a narrower viewing angle, for example.

If you may use a number of projectors on the screen to be purchased then select it for the model with the lowest brightness.