Choice and application of different projection screen surfaces
There is a vast difference between screening a film in a purpose built cinema auditorium to screening for an indoor or outdoor event such as live theatre or opera, fashion shows, film premiers, and touring shows.
There are even differences between indoor auditoriums that will dictate the type of screen surface you opt for.
The good news is there are several types of screen surface available to match different environments – including outdoors. They include:
- Pearl (Perlux)
- Matt white
- Rear projection
- High contrast grey
- Woven acoustically transparent projection screen
Things to consider when choosing a surface
As well environment and the size of the space, you also need to consider where the screen will be positioned, and if you will be projecting from the front or rear.
Each type of screen has what is known as a gain value, which is defined by how much brightness is visible from the screen’s centre.Gain is affected and controlled by the screen’s diffusion. It also dictates how light from the projector is scattered.
Consistent brightness across the screen surface, together with minimal hot-spotting, is needed for the best viewing experience. As well as the type of screen surface you choose, this will be determined by the size of the room, the amount of ambient light, and of course the type of projector used.
You should also opt for the highest quality screen material you can afford to avoid discolouration and structural loss.
Auditorium size is a major consideration as this will affect the distance from projector to screen, where the screen will be positioned, and how close the seating will be to the screen.
Proximity to the screen also determines whether or not you choose a screen with perforations, and if so, which type you opt for.
We’ll cover this later, but first let’s look at the different surfaces and the environments to which they are best suited.
Peal and Perlux® surfaces are reliable and durable, and give excellent results for 2D screening. They offer the best quality viewing in most indoor auditoriums but particularly so in largervenues where the screen will be centred. This type of surface gives out more light and spreads it further so it will reach the sides and back of the auditorium more effectively.
It has excellent gain characteristics, plus the best viewing angles, highest contrast and the brightest images of any surface.
Perlux® brand screens reflect more light back to the audience, and appear seamless under normal lighting conditions, which also improves the viewing experience.
They can reduce operating costs too as less power is needed from the projector. This means smaller lamps can be used, which don’t need to be changed so often.
White or matt surfaces are the most economical available and offer good visual results in a wide range of cinemas and auditoriums, including the home.
This type of surface provides a seamless image, with high contrast and bright colours, as well as extra-wide viewing angles.
Silver. When cinema began, all screens were silver. It was a good option because silver reflects more light than a white screen, and projection systems weren’t as powerful as they are today.
As projection improved, white screens became more widely used. However, the 3D film format has resurrected silver because other surfaces are darker and therefore not as suitable.
The percentage of light reflected by other surfaces varies strongly with the direction of polarisation in 3D films, which is not the case with silver.
Also, because of the filters needed for 3D projection, the overall image isn’t as bright as it would be with normal projection. Silver screens help to compensate by reflecting back more light than other surface types – just as they did in the early days of cinema.
The most technically advanced silver screens are ultra-bright and really bring the characters to life. They also perform well with 2D movies.
Rear projection screens are used in smaller auditoriums that don’t have a projection box but have space behind the screen. They are also used a lot in simulators such as those found on theme park rides.
They are available with a range of economical rear projection surfaces, including a combined front and rear projection.
Rear projection screens use a formulation that uses an unsupported PVC base with built-in diffusion to overcome hot-spotting. They are excellent in a variety of ambient lighting conditions, meet a good variety of contrast and transmission requirements, and are also ideal for edge-blending projection.
The screens have no visible seams under projection conditions and can be folded for transportation which makes them perfect for events. They are also suited to control centres, conference rooms, and theme park rides.
High contrast grey
High contrast surfaces are designed for use with LCD or DLP video projectors that aren’t optimised to project black or near black colours.
The grey surface reinforces the blacks and enhances the contrast. They are intended for a variety of auditoriums, generally in dark conditions, though they can also minimise the effects of ambient light
High contrast grey is a coated vinyl with a gain level of 0.6, and is available perforated or non perforated – the choice depends on where the speakers are placed.
The seam welding process ensures the screens have no visible seams under projection conditions.
High contrast grey surface screens are ideal for cinemas, events, and in film production.
Sound as well as vision
You need to take sound into consideration, together with image quality, when choosing a suitable screen surface for your venue.
The optimal position for the speakers is behind the screen. Consequently, surfaces have been created with perforations to allow the sound to come through while also minimising light loss.
There are different types of perforation: standard, micro and mini, and choice is determined by the size of the auditorium.
Standard perforations give better sound but in smaller venues, where the audience is closer to the screen, the holes will be visible.
Mini perforations are better for viewing a film close up, say within 16 feet of the screen. The tens of thousands of perforations, which are less than .025” in diameter, allow sound to pass from the speaker through the screen.
Sound quality isn’t quite as good as with standard perforations, but digital soundtracks mean it’s only slightly reduced, and it’s a good trade-off to gain better image quality.
Woven acoustically transparent projection screen, The screen, which provides better sounds quality, has a special surface which lets sound waves travel through the material without impeding them.
Outdoor and event screenings
Inflatable air screens are becoming more popular for outdoor and one-off events and they can be supplied with different surfaces.
The weather and light conditions are the most important factor in determining which surface type to choose. And of course the time of day the screening will take place will be important.
Perlux is your best option for daylight or dusk matt or dark venues with no ambient light. While matt can be used, it’s not always recommended.
Another thing to consider is whether or not the screen is likely to get dirty. Matt and pearl screens can be cleaned, and in fact, luminance and gain increase which improves image brightness.
However, silver screens are very delicate and should only be considered as a last resort where the only other option is to change the screen.