Although there are now many options with regard to visual support, projection is still the usual method of displaying PowerPoint slides, video, live cameras etc.
Front or rear?
The first decision to be made is whether to use front or rear projection. This simply means positioning the projector in front of or behind the screen. The usual factors governing the decision are the room capacities and actual audience size for the event. For instance if the room capacity is 200, with the actual audience numbers being 140 then there will be enough available space to rear project. If the audience numbers are 180 however, then front projection will have to be used. In most cases rear projection is preferable, as the projection system is situated behind the screen out of sight, and without the beam of the projected image on the front of the screen which could be walked into by presenters on stage.
Projection distance – how far?
The next decision is how much projection distance (or ‘throw’) we need between the projector and screen. Again, this decision is usually based on audience size and room capacity. As a general rule, the projection distance is calculated as 1.5 times screen width. For example, an 8ft screen width would be calculated as – 8ft x 1.5 = 12ft projection distance Given the advances in technology, interchangeable projection lenses can be used to compress this into smaller distances should room space be tight in the same way ‘zoom’ lenses are used for front projection to enable projection systems to be placed some distance from the screen.
