Projection Screen Advice
Choosing the right type of screenBroadly speaking projection screens fall into two categories, portable and fixed installation. Initially which type of screen you require will be determined by circumstance. If you are looking to set up a screen permanently then choose a fixed installation type, if you need to be able to rig and de-rig a screen as required then you need portable.
Fixed Installation ScreensScreens that you install permanently are referred to as fixed installation. Examples include fixed frame, manual pulldown and tab tensioned amongst others. Which type you choose boils down to personal preference, budget and ease of installation.
For the smallest budget, a manual pulldown screen is best. They will come with either keyhooks and loops or adjustable brackets making them relatively quick to install. Keep in mind that the cheapest screens will be more susceptible to the case twisting during installation (so additional care should be taken) and the component making up the screen fabric will be more likely to ripple over time, distorting the image.
The next step up from manual pulldown is electrically operated retracting screens. These operate in a similar fashion to their manual counterparts but have motors mounted either inside the tubes (the neatest and most common solution) or at the end of the tube. They can be activated either by in-line switch in the power cord, wall mounted switching, remote control (IR or RF) or with a 12V trigger if your projector has the facility. Note that the same issues as manual screens can be an issue with cheaper brands. In addition the construction of mechanical parts and the motor may not be of the same quality as better brands.
There is an interesting variation on electric screens known as Variable Aspect Ratio Screens. These allow you to change the aspect ratio of the screen to match whatever source you are watching. For example DVD are commonly available in 4:3 (Video), 16:9 (Widescreen) and 2.35:1 (Cinemascope) aspect ratio, each of which can be watched on a variable aspect ratio screen without loosing the black borders around the image (we'll discuss the importance of the black border later in the article).
The ultimate in retracting screens is the Tab-Tensioned Electric. By using tensioned wires tabbed down each side of the screen the surface can be kept flat giving perfect geometry. This type of screen does tend to be expensive but is the best to use in a non-dedicated room.
Fixed frame screens are the ideal solution for dedicated projection rooms or where the screen does not need to retract when not in use. They are assembled from four lengths of aluminium which form a fixed rectangle over which the screen fabric is stretched. Once fixed to the wall the screen form a perfectly flat surface ensuring perfect image geometry.
Portable ScreensFor the presenter on the move, or any situation where a screen cannot be permanently installed, a portable screen is the solution. They are available in a number of different forms from basic pull up screens to folding frame and truss frame.
Tripod screens are the lightest (compared to size) of any portable screen designed to be viewed by more than a few people. When transporting they fold down to a thin tube slightly longer than the width of the screen and when you get on-site simply unfold the legs and pull the loop to raise the screen surface. They are height and aspect ratio adjustable but the fabric is rarely perfectly flat.
An interesting alternative to tripods are pull-up screens. These are a long (width of screen plus a few inches) tubes that lie on the floor and you simply pull the screen surface up. Of all the portable screens these are probably the easiest to set up but are heavier than the equivalent size tripod and suffer from the same potential rippling of the surface.
Folding screens are designed for heavy use or large applications. They are available from 6ft to around 25ft wide in 4:3 and 16: aspect ratios in front and rear projection forms. They are made up of an aluminium frame to which the screen fabric is attached and adjustable height legs. Assembly takes place on site and they can be folded down into supplied carry cases.
©Ken Davies, Ivojo Multimedia Ltd.