In the last decade, as movie theatre tickets soar sky high, more and more people are using front projection systems at home. And I've been asked many times for advice on which projection screen to buy.
You have to match the screen to the projector you're using. While this often means you have to spend more than you might have anticipated, the truth is that you cannot use a projector without a suitably matched projection screen that allows you to squeeze every last ounce of your projector's performance.
A middle-of-the-road projector used with a perfectly matched screen can easily beat a high-end projector that's projecting an image directly onto a wall. It is a complex marriage and delicate balance between a projector and screen, along with factors like ambient lighting, room colour, and viewing distance. It is best to hire an independent THX/CEDIA certified home theatre designer (read: a designer that is NOT working for any store to avoid bias). But it's always a good idea to have some basic knowledge of the components so you don't end up being blindly guided.
First, you have to determine your viewing distance. In a home theatre setting, it is not recommended to put your seats all the way back against the wall. You want the rear speakers to be behind you to provide an enveloping soundfield. Second, projectors have cooling fans. In order to prevent the cooling fan from being heard too loudly, you'll need the projector to be located at least one foot behind your seat. Don't forget that the projector itself will require a depth of about another foot. In order to establish your furthest viewing distance in any given room, measure the depth of the room and deduct at least two feet, although five feet will be the ideal in most cases.
Choosing the right screen size and the right aspect ratio will have a huge impact on the long-term enjoyment of your theatre, so give these matters serious thought. When it comes to a successful home theatre design, these factors are as important (sometimes even MORE important) than the projector you choose.
After determining the viewing distance, you can easily determine the screen size. There is no right or wrong size although there are two common screen size recommendations. One is as per SMPTE recommendation; another is as per THX recommendation, which recommends a larger screen size to give a more enveloping sense of vision.
My rule of thumb is that the most comfortable viewing distance is, at most, approximately 1.5 times the width of 16:9 screen; or in the case of Constant Image Height (CIH), equals the width of a 21:9 (2.35:1) screen. If you sit closer than that, unless you will only be viewing Blu-ray Discs with top notch transfer quality, you'll just be torturing yourself since various artefacts will become more visible and intolerable. In my UHD-only home theatre set up, I'm viewing a 96" 21:9 screen from nine feet away. When I'm watching the odd HD movie, I zoom out and watch an approximately 86" 16:9 area from the same nine-foot viewing distance.
Also bear in mind that just because your wall is (say) 10 feet wide does not mean using a 10-foot-wide screen is recommended. Give the screen some "room to breathe." If you are using regular speakers, usually you will need at least one foot of space on either side of the wall to put the speakers, although two feet at each side is best if you have the room. Even if you install the speakers behind the screen, you still want to have at least one foot of room to breathe on either side (again, two feet will be ideal) to avoid light reflecting from the screen to the side walls. This can give an illusion of lower contrast (read: bad black level) or at the very minimum, simply be distracting.
My suggestion is to be conservative in the size of screen you choose because most projectors below the $10,000 mark tend to be maximized for approximately 12 foot-lambert to 22 foot-lambert brightness at around 120" diagonal (at 16:9 in 2D) or 96" diagonal (at 16:9 in 3D mode) as per SMPTE Standard 196M Luminance Level. (Side note: THX specify 16-foot-lambert to be the minimum Luminance Level). Even in my own home, I use 22 foot-lambert as my bare minimum brightness.
Next week, I'll cover the topic of Screen Gain, discussing what it is, how it works, and why it is important to get it right, especially in the 4K HDR world.