Projection Screen Advice
The following advice is aimed at helping you to select the best screen for your particular application.
Should you still need a little help, please feel free to give us a call. Years of experience have helped us to fully understand the variables involved in selecting the perfect projection screen and we are more than willing to share our knowledge.
Important Terms:
Gain:
Gain refers to the radiation from the screen in a specified direction divided by the radiation in the same direction from a lambertian (0 gain) screen under the same conditions.
Thus a gain of 2 means the picture is twice as bright as when viewed on a lambertian screen, under the same conditions.
See for yourself:
This split-screen test uses a 2500 Ansi lumen DLP projector in a slightly lit environment (20 LUX ambient light measured on the screen surface).
Left bar: 1:1 Standard screen material.
Right Bar: 20:1 Lumin Silver Screen.
Ambient Light:
Ambient light is the amount of light in the room/area in which the screen is to be installed, measured in lux. Ambient light has a signifacant affect on projection screens as the higher the ambient light, the more professional the required solution.
A note on Direct Sunlight - There is no front projection solution that can be used under direct sunlight. Rear projection screens, however, are far less susceptible to the effects of direct sunlight and, if the solution is spec'd correctly, they can be used under direct sunlight conditions.
| Illuminance | Example |
|---|---|
| 0.002 lux | Moonless clear night sky with airglow |
| 0.01 lux | Quarter moon |
| 0.27 lux | Full moon on a clear night |
| 1 lux | Full moon overhead at tropical latitudes |
| 3.4 lux | Dark limit of civil twilight under a clear sky |
| 50 lux | Family living room |
| 80 lux | Hallway/bathroom |
| 100 lux | Very dark overcast day |
| 320–500 lux | Office lighting |
| 400 lux | Sunrise or sunset on a clear day |
| 1,000 lux | Overcast day; typical TV studio lighting |
| 10,000–25,000 lux | Full daylight (not direct sun) |
| 32,000–130,000 lux | Direct sunlight |
Standard 1:1 gain screen:
These two images show the effects of ambient light on a projection screen. This screen is a 100" 4:3 Standard Front Projection Screen with a gain of 1:1. A 2,500 lumen DLP projector is being used.
Image 1: Lux @ 10. Image 2: Lux @ 70
Of importance is to mention that you do get screens that are less affected by Ambient Light than standard screens. These screens are manufactured using a Silver Aluminium coating and are often referred to as Silver Screens.
The following images show a Lumin Silver Screen home cinema installation using a 1,200 lumen Full HD projector. The images show the effectiveness of the screen under no light and ambient light (70 Lux) conditions, also shown are images of the viewing angles achieved with the Lumin Silver Screen.
Screen Ratio's:
Different screen ratios are required for different applications and it is crucially important to select the correct ratio for your application so that you avoid being left with unused screen space. The following is a list of the different ratio's and their application areas (WxH):
Over Head Projection - 1:1
Video/Data - 4:3
Wide Screen - 16:9
Cinema - 2.35:1
Please ensure that you request measurements according to these ratio's, for your application.
Installation Types:
Home Cinema (Movie Theatre):
In a cinema, the screen is a reflective surface which may be either aluminized (for high contrast in moderate ambient light) or a white surface with small glass beads (for high brilliance under dark conditions). The screen may also have hundreds of small, evenly spaced holes in order to allow the passage of air to and from the speakers and subwoofer which are often directly behind it.
Fixed Frame:
Fixed frame screens maintain their geometry perfectly just like the cinema screens, which makes them suitable for applications that demand exact reproduction of image geometry. These screens are often used in home theaters and boardrooms.
Pull Down:
Pull-down screens (also known as Manual Wall Screens) are often used in spaces where a fixed frame screen would require too much space. These use screen material that is rolled in the screen case when not used, making them less obtrusive when the screen is not in use. These screens are often used in home theaters, boardrooms and portable applications.
Motorized:
Motorized screens can be wall mounted, ceiling mounted or ceiling recessed. These are often larger screens, though motorized screens are available for home theater use as well. Motorized screens are usually raised or lowered using either a remote control, wall-mounted switch or both, although some projectors are equipped with an interface that connects to the screen and automatically lowers the screen when the projector is switched on and raises it when the projector is switched off.
Portable:
Portable screens usually come in either a pull-down on a tripod stand or pull up from a weighted base formats. These can be used when it is impossible or impractical to mount the screen to a wall or a ceiling.
Inflatable (specially manufactured by JLSS):
Inflatable screens are usually reserved for large crowd events and can take on several different forms. Applications include indoor front and rear projection, outdoor night front and rear projection and outdoor daylight rear projection in either floor standing or helium filled floating formats.
Screen Material Types:
Matt White:
Matt white material is often referred to as Standard Material and usually has a gain of between 1 and 1.2. These screens can only be used in areas of complete darkness where ambient light is completely controlled.
High Gain:
High gain material is manufactured in a way that allows for the maximum amount of even image dispersion over the entire screen surface and allows for brighter image radiation on the 90 degree parallel. Gains vary between 2 and 2.8. High gain material was specifically developed for use under relative ambient light conditions. Application areas include Home Theatres, Boardrooms and Conference Centes.
Silver Screen - Extreme High Gain:
Silver Screens offer gains of between 5 and 20 and are manufactured to allow for the widest viewing angles possible while still giving great image quality. These screens are usually very expensive and are thus only used in Home Cinema's and High Ambient Light Retail Environments.
High Contrast Grey:
High contrast grey screens are manufactured to offer extremely high contrast ratio's with the goal of darkening/deepining the black colours. Gains vary between 0.6 and 1 and are the ideal solution for Full HD Home Theatres. The black enhancing features mean that these screens should not be used in Boardrooms or other presentation environments as it is the whites that need to be enhanced for these applications.
Rear Projection:
Rear projection screens are available in several different formats with different materials used depending on the application. Formats include rear projection film, fixed frame and solid screens for indoor and outdoor projection use. Gains vary between 5 and 20 but it is crucially important to select the correct material and format for your application as some screens allow no light to pass through while others are completely clear allowing all light to pass through.
Rear Projection Film Types:
Holographic (Transparent) - A film that permits 90% of the transmitted light to pass through. It is completely transparent when not projected onto but displays an image when projected onto.
Grey (High Brightness) - A film with a sand blasted colour. This film offers extremely high brightness and is ideal for applications where bright and vivid colours are required. This is the most popular type of film in use today. The only draw back to this film is that it creates a hotspot if used with a short throw projector.
Dark Grey (High Contrast) - A film with an almost black colour. This film offers the same gains as the high brightness film but because of its darker colour, it offers deeper blacks. This film will not hotspot with short throw projectors which makes it ideal for use in applications where space is an issue.
Dual View (Double Sided):
Dual View material allows the projected image to be viewed in crystal clear clarity on both sides of the material. Formats include film, fixed frame and solid screens with gains varying between 5 and 20. In essence, these screens achieve the double sided properties by transmitting 50% of the projected image and reflecting the other 50%.
Important Information:
Portable Screens:
Both mobile and permanently installed pull-down screens may be of a tensioned or not tensioned variety. Tensioned models attempt to keep the fabric flat and immobile, whereas the not tensioned models have the fabric of the screen hanging freely from their support structures. In the latter, the fabric can rarely stay immobile if there are currents of air in the room, giving imperfections to the projected image.
Dual View (double sided) Screens:
Double sided screens cannot be used in applications where words are to be projected. Because you only project onto one of the sides and set your projector up accordingly, any words projected will be displayed backwards on one of the sides.
A solution to this dilemma is to design your content with the same words on two lines but written in both directions (normal and reverse).
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