by Jay Ward
I understand that this article may be somewhat technical, but if you take the time to read ahead you will learn the basics of projection technology. Hopefully this will help you gain a better understanding of this critical element to most programs, saving you time and money in the long run.
Size is probably the most important projection consideration. Generally speaking, the last row of seats should never be more than six to eight times farther than the height of the screen. For example, if you are using a 9 foot high by 16 foot wide screen, the last row of seats should be no more than 72 feet from the screen. Also, the nearest seat should never be closer than the height of the screen; so in my example the nearest seats should be no less than 9 feet from the screen.
These screen size formulas are more guidelines than strict rules. Depending on the visual content being displayed, these distances may be extended or may even need to be reduced. For example, if you have very detailed presentations for engineers who will be viewing technical diagrams on screen it may be necessary to reduce the distance to the last seat. In this instance four times the screen height may be prudent. If you are only using the screens for actual video content then it is usually acceptable to have the last row be eight or nine times the screen height from the image.
The best advice is to trust your judgment. If you feel that the screen is too small (or even too large) then it probably is. Unfortunately these onsite judgments cannot be made until it is usually too late to make the necessary changes. These formulas are a great tool to use for advance preparation when all you have is a room diagram to make these decisions. Room diagrams can be very misleading, but if they have accurate dimensions it is nice to have some reliable formulas.
The aspect ratio of the screen is simply the difference between the width and height. Before high definition, the standard aspect ratio in North America was 4:3 (width x height). For example, a screen that is 4 feet wide would be 3 feet high. The standard high definition aspect ratio is 16:9. Considering all televisions, and most computer screens, are in this aspect ratio (some computers are 16:10, but close enough), I recommend only using 16:9 screens and requesting that all content for your programs be created in this format. This is important for several reasons, but mostly it keeps your setup looking fresh and modern.
Front or Rear Projection
If you have the space, rear projection (RP) is usually the best option. Rear projection allows for a cleaner look by not having a projector somewhere in the room, and it allows for presenters to walk in front of the screen without getting in the way of the projected image. The only real additional cost to RP is the fact that you usually need to use some sort of drape or hard scenic elements to hide the backstage area and the projector.
Front projection (FP) typically allows for more seating space because the screen can be set up against a wall. The main issues you will encounter when using FP are how to keep the presenters from walking in front of the projector as well as placement of the projector itself. There are many creative ways to utilize FP when necessary ranging from ceiling rigs to long throw lenses to towers in the back of the room. With a little imagination you can usually make FP work.
Projectors come in many different shapes and sizes. Renting projectors can get quite expensive so it’s very important to figure out exactly what the job requires. This is a place where planners often overspend on something that they just don’t need, or don’t spend enough and simply don’t have quality visuals for the presentations or video.
There are no magic formulas to figure out what projector will work best for your application. A simple thing to remember is that DLP is better than LCD (for several reasons that I will not go into here). If you can afford DLP then it may be worth it for your higher budget events, but in most applications a bright LCD will do just fine. The real key is to not mix DLP and LCD in the same room. That is when the differences between the two become obvious.
I would like to take a moment to comment on backup projectors. In my opinion there should always be at least one backup, if not multiple “online” backup projectors onsite. While failure is rare with newer projectors, there is simply no way to predict when a lamp or some other internal component will fail. This risk is reduced greatly by proper projector maintenance, but this can never really be guaranteed. Any time you rent a backup projector your AV supplier should only charge half the rental price of the main units.