(Hint – It’s NOT Glass Beaded)
A new opportunity arrives on your desk and you have to specify a projection system – it could be a large auditorium or a small classroom. What screen will you use? There is a great deal more to choosing the right screen than many of us realize. If you haven’t studied screens recently perhaps a little time learning about the differences in aspect ratio, surface materials and all the other options would be to your benefit and more importantly to the benefit of your customer.
- How much light will be in the room during use?
- Will any light shine directly on the screen (whether from a lighting fixture or a window)?
- How far away from the screen will the farthest seat be?
- How wide will the seating be in front of the screen?
- What will be shown (Movies or Computer Presentations)?
- Is it Front Projection, Rear Projection, Standard Lensing, Ultra Short Throw Lens?
- How bright is the projector?
- Is it LCD, DLP, LCOS, LED or Laser Projection Technology?
All these questions and many more weigh into the correct decision. Let’s delve into a few of them.
The screen size should be determined by the size of the text that will be displayed and the distance to the farthest seat. The accepted formulas are as follows:
- Displaying presentations when text is 12 pts or larger: The HEIGHT of the screen should be 1/6th the distance to the farthest seat. Example: If the farthest seat is 30’ from the screen surface then 30 ÷ 6 = 5’ (60”) high. If displaying spreadsheets and other smaller text the ratio should be 1/4th the distance to the farthest seat. For very complex graphics the ratio can be as low as 1/2.
- The bottom of the screen should be 3.5’ to 4’ from the floor for non-tiered seating (so that the bottom of the image will not be blocked by people’s heads sitting in the front rows). With tiered seating the height off the floor can be as little as 2’.
How do we determine whether it should be 4:3, 16:9, 16:10, 15:9 or another format? This is dictated by the images being displayed. Today most computer images are 16:10 (although a few are 15:9 and older computers display 4:3). Make sure the projector you specify provides the same aspect ratio – preferably its native aspect ratio.
Movies (and television) also are available in several aspect ratios – high definition television broadcasts are 16:9 but some movies are delivered 1.85:1.00 (Letter Box) and CinemaScope is delivered in a 2.35:1.00 aspect ratio.
And then there is the reflective quality of the material.
- Matt White is the most common surface as it diffuses light in all directions providing a 1:1 gain and a 180 degree viewing cone.
- Grey material improves contrast making blacks blacker (although whites aren’t as white). The preferred screen for showing movies and video’s (thus the “Silver Screen” at the movie theater).
- And newer screen fabric technologies made specifically for higher resolution projectors of today. (For more information on projection screens please use this link to read our Tech Tip)
- Glass Beaded screens should have gone out of production at least 10 years ago when high lumen projectors became common and reasonably priced. But they are still being made and sold mostly because architects continue to specify them. They were created to “amplify” light when projectors were less than 200 lumens by reflecting the light toward the center of the room and it worked! There is a bad trade off however as the screens offer a narrow viewing cone and there will always be hot spots. DO NOT SPECIFY THEM and if you see a bid spec for them please get the specs changed. You will do everyone a huge favor.
Other screen features to consider are manual or electric (and consider all the options such as return mechanisms and how quiet a motor is). There are screens for outdoor use, screens with tab-tensioning (for the flattest surface), portable applications, rear projection, screens that reject ambient light, for ultra-short throw applications, fixed frame screens with integrated writing surfaces (for white boarding), even for instances when speakers are behind the screen.
These comments just scratch the surface when it comes to picking the right screen. Most screen manufacturers offer excellent information on their web site for better understanding how to choose the correct screen and as always you are welcome to contact your Almo representative for additional guidance.