Broadly 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 Screens
Screens 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.
Beamax R Series manual screen
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.
Somfy tube motor
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 (th neatest and most common solution) or at the end of the tube. They can be actived 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 cheper brands. In addition the contrsution of mechanical parts and the motor may not be of the same quality as better brands.
There is an interestig 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).
Draper Premier Tab-tensioned screen
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 essuring perfect image geometry.
Portable Screens
For 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 tripod screens to folding frame and truss frame.
Harkness tripod screen
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 potentual 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 fabic is attached and adjustable height legs. Assembly takes place on site and they can be folded down into supplied carry cases.
The right size
For presenters
Choosing the right size of screen can be the trickiest issue for the first time buyer but there are guidelines available. In an ideal situation calculating the desired image size is fairly simple and is based on audience viewing distance as a ratio of the height of the image. This ratio should fall between 1.5 and 6:1, in other words the minimum view distance should be 1.5 times the screen height and the maximum 6 times the screen height in order for everyone to be able to see the screen clearly. This formula works well for designed projection installations and offers a fair amount of leeway for general purpose rooms. Keep in mind the limitations (both in throw ratio and light output) of your projector and the ambient light in the room. The larger the screen the brighter the projector needs to be. We'll discuss this more later.
Home Cinema
The situation is sometimes more difficult for home users as there can be a lot more factors on selecting screen size:
Phyical limitations.
The location of the screen may well limit the size you can or want to install. If you're using your living room as a home cinema room then you may deside to purchase a screen which nicely covers a window, so reducing ambient light. You may be limited by the throw distance of the projector. If you are looking at installing the projector at a particular point then you will need to select a screen suitable for the minimum and maximum size the projector can throw from its location. The vast majority of projectors that Ivojo supply have throw figures quoted. Select a projector and scroll down its specification page to the throw chart and click the "Info" button. On the page that appears you will see a chart and a couple of table and under the "Select a screen" section you can select from any of the screen Ivojo supply and throw distance figures will be returned. A similar feature is available if you look at the specifications of a screen, you can select from a list of projectors to be given throw figures.
Light Limitations
We'll be going into detail on amibient light later on but - breifly - keep in mind that if you are using your living room for home cinema then you are not likely to be able to control ambient light completely and your projector has a finite light output so the screen must not be so big that the image is too dim to comfortably view.
Comfortable Viewing
The sizing guidlines given above can be useful guidelines but are a bit to broad for home cinema use. This is very much a subjective decision but remember you want to get the "cinema" experience without the "sitting in front row craning neck" experience (the 1.5 times screen height figure is not a bad starting place). If this is to be your first time with home cinema then we would generally adive you to purchase the projector first and use it against a pale wall for a few days. Once you are happy with the image size, measure it and order the appropriate screen. If you need any assistance then please phone us on 0845 126 0530 or email us.
