Home cinema projection screens: how to choose
24th Nov 2010 | 14:10
Which type, size and aspect ratio is best for you?
How to choose a home cinema projection screen
At Home Cinema Choice magazine, we talk a lot about projectors, and not much about projector screens.
But this doesn't mean we don't find screens as interesting, or consider them less important to the home cinema experience.
Far from it. One reason we don't review more screens is a practical one; installing and handling such large and cumbersome items can be a nightmare. But the other reason is that the screen market is so diverse, and associated so closely with the specific needs and room conditions of each user, that reviewing individual screens would seem too specific to be worthwhile.
The fact is, though, that if you get the screen wrong, then you will be selling your projector short, no matter how expensive it might have been.
Which type should I choose?
Start off by looking at the different types of mounting options available. There are two main approaches: fixed frame, where the screen is placed in a rigid frame and attached permanently to the wall, or 'roll-away', where it can be rolled up when not in use.
Within the latter category there are also various sub-options we'll consider in a moment. For people lucky enough to have dedicated home cinema rooms, the fixed frame approach will often be the simplest, since the screen doesn't need to be hidden when not in use. It's widely considered, too, that permanent screens stay more tautly stretched and thus produce more accurate pictures.
Roll-away screens are obviously a great solution for people trying to accommodate a home cinema setup in a room that also gets used for other activities, such as a living room. The most basic of these screens sit on a roller attached to, or hidden in, the ceiling and the user has to manually pull the screen down when needed.
Also very popular is the motorised roll-down variety, where motors drive the screen down into position at the touch of a remote control button. Some projectors carry 12V trigger outputs, in fact, so that they can activate motorised screens automatically when the projector is switched on.
If even having a slim roll-out screen housed on your ceiling feels too intrusive, a further, portable option is the pull-up projection panel. these come fixed inside carry cases that you stand on the floor, so that the screen pulls out of the top and is held upright by a collapsible support frame.
We've found that the more affordable floor-mounted types may not always stand completely upright or even flat. But the fact that you can put them in a cupboard when you're not using them is a practical benefit that will justify the performance compromises for some. rigidity and perfect flatness, so crucial to a good picture, are often one of the main reasons some projector screens cost vastly more than others, especially in the roll-away department.
Projection screen aspect ratios
Another key decision is which shape and size of screen you should go for. In terms of shape, there are three aspect ratio options: 4:3, 16:9, and 21:9. For home cinema enthusiasts, the old 'square' 4:3 screen approach is almost certainly a nonstarter these days. Which leaves us with 16:9 or 21:9.
If you intend to watch a lot of HD, you will probably be best off with a 16:9 screen that matches the ratio of HDTV material. If you're a die-hard movie fan, though, you might consider a 21:9/2.35:1 CinemaScope screen. After all, most big films now are shot in 2.35:1, and so the majority of Blu-rays are produced with that aspect ratio.
However, the situation isn't totally cut and dried. Blu-rays don't currently hold 'true' 21:9 masters (instead adding black bars within the picture data), and projectors don't have true 21:9 pixel ratios. So if you want a full 21:9 experience, you need a projector with a CinemaScope lens attachment – something which can add considerable cost to your projector setup.
If you really want the ultimate in Cinemascope clarity you could consider a curved screen like Stewart's CineCurve (below). These give a more immersive effect, focus light at your viewing position and compensate for the lens distortion you get with anamorphic lenses.
It's curtains for you
The existence of multiple aspect ratios explains another popular option: masking, where absorbent material can cover parts of the screen to change the shape of the visible section.
On a basic level, this can be done manually using curtains, although it is quite a faff. You can also install a motorised curtaining system external to the screen. But by far the most elegant solutions are high-end fixed screens that have motorised masking, where black borders of absorbent material can be electronically moved out from all four edges of the screen.
Such screens usually ship with preset aspect ratios and are selectable using single remote control buttons, but you can usually manually tweak the border locations yourself too.
To be really effective, the movable borders on these sorts of projection panels need to absorb light extremely well. And such screens are generally hugely expensive because of both the motors and tracking mechanisms involved. But they're generally an excellent proposition when built well enough, especially if you regularly watch 21:9 material, but don't want a CinemaScope lens or 21:9 screen.
Choosing the correct projection screen size
Choosing the correct size is more complicated than you might think. Aside from the size of your wall you need to consider at what distance from the screen your audience will sit, which is down to personal preference.
When people go to the movies some like to be relatively near the front, others prefer the back, while some will only sit the middle. And so it is at home, where people like to have different screen sizes relative to their preferred viewing position.
Screen size also depends to some extent on the quality of your projector and screen. If neither is particularly good, sitting too close will only make you more aware of the shortcomings.
Finally, it's a simple fact that how large a screen your projector can drive is dependent on the amount of brightness its lamp can produce. So while 'light cannons' such as Sim2's spectacular C3X Lumis can drive screens many hundreds of inches across, you might find relatively low brightness projectors struggling to keep images looking punchy over 80-100in.
We mentioned screen material earlier and it's this aspect of screen selection that's the most bewildering yet, potentially, crucial.
The first decision you need to make is quite simple: do you want to mount any speakers behind the screen? If so, you'll need an acoustically transparent, perforated fabric that enables sound to pass through without becoming muffled or blocked. Such fabric can cause problems with reduced brightness and back wall light reflections, as light passes through the acoustic holes.
No pain, no gain
After this basic decision, though, life gets more complicated. For a start, you have to get grips with the concept of gain. Some screens are high gain, while others are low, with all sorts of ratings in between, and each gain value has its place.
Many white home cinema screens tend to be low gain, with values written as 1.0-1.3. these gain figures, rather archaically, describe the ratio of light a screen reflects in relation to the amount of light that gets reflected by an untreated magnesium oxide board. so a 1.3 gain screen will reflect around 30 per cent more light than our lovely magnesium oxide white board.
The growing interest in black-level boosting screens that use a grey material rather than white is resulting in gain figures below 1.0 appearing, too. The question of whether you should get a high or low-gain screen, again boils down to matters of taste and, more importantly, room setup.
For instance, high-gain screens have reduced viewing angles versus low-gain ones, which could be an issue if viewers will have to sit to the side of the screen. High-gain screens can suffer from hot spots too, where the centre of the image looks brighter than the rest. And finally, high-gain projection panels can damage colour balance, since they don't reflect red, green and blue equally from all viewing angles.
But before you discount them, if there's often a degree of ambient light in your movie room, the high-gain variety could be essential. In fact, a few have been developed now with extreme gain properties, specifically to try and emulate (for a fraction of the cost) the performance of, say, a massive (80in plus) plasma screen in a normal living room environment.
A particularly outstanding example of this is the screen Innovations Black Diamond II we tested in issue 183.
Dedicated, blacked out home cinema rooms might be better with more standard-gain screens, though, and possibly even a grey sub-1.0 gain screen. Grey screens were extremely worthwhile a few years ago before projectors started to produce impressive contrasts, but they arguably still have a place even if you've got a good high-contrast projector.
If your viewing room is either decorated in light coloured finishes or else houses numerous light furnishings, the way grey screens stop light bouncing around a room could prove very useful.
One final consideration is the issue of the quality, finish and weave of the screen you buy. We've heard various cynics suggest that expensive screen materials don't really make a difference. But this is just plain wrong. We've seen first-hand how some screens really can produce sharper, more detailed images with HD than others.
Also, some screens can cause a slight moiré effect over areas of fine detail while others don't. Some screens, as previously discussed, are brighter and more reflective than others, and some are better at reproducing a convincing black colour. Some diffuse light right around your room for wide viewing angles, while others focus it right back at you. Some reproduce colours completely neutrally (and thus accurately), others can introduce an underlying tinge of their own or favour certain tones over others, leading to an unbalanced colour palette.
We're even starting to see screens appearing now that claim to be better for 3D than others. This might seem spurious at first glance, but actually stereoscopic pictures need utter clarity for high levels of detail and really accurate colour toning to become convincing, so we can understand some screens working better with the technology than others.
One of the first screens designed and tested with 3D in mind is Image screen's Cadre 3D.
Finally, the basic quality of the fabric in terms of wear and tear, hanging weight and resilience to rolling, with roll-away projectors, can have a massive impact on long-term viewing. You would be well advised to get help from custom installation experts before finally settling on a screen.
And try to partner your projector with a screen of as much quality as you can afford. After all, unlike a TV, a high quality screen should last you a lifetime.
First published in Home Cinema Choice Issue 187
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