H O M E C I N E M A
An Introduction to Projection Screens
Video purists usually tend to choose constant-height screens. This means that as you switch aspect ratios from 4:3/1.33:1 (or even down to 1.19) to 2.40:1 (or even 2.55 or beyond) the screen height remains the same. Having said that the screen needs to be matched to the room, viewing distance, and the projector—and there are reasons why a constant-height screen is not always the best for certain applications. Screen masking is another subject about which a lot could be said, but to keep things simple the goal is to mask all of the aspect ratios that you would use. Adjustable masking is desirable because that way the aspect ratio of the projected image that you are watching is bordered on all 4 sides by movable black panels, thus framing the white screen area where the image is viewed within a non-reflective black border. For a comparison of a Constant Height vs. Constant Width screen click here.
The Ultimate in Projection Screens
Take for example a 60" constant height screen. The 4:3 image will be 60" x 80" which is 4800 square inches. The 16:9 image will be about 60" x 107" which is about 6400 square inches. Whereas the 2.40 image will be 60" x 144" which is 8640 square inches. Compare that to a 70" x 144" 4-way masking screen, which is the same 144" width as the above. The 4:3 image will be approximately 70" x 93" which is 6533 square inches. Whereas the 2.40 image will be the same 60" x 144" which is 8640 square inches.
Or compare that to an 80" x 144" 4-way masking screen, which once again is the same 144" width as the screen example above. The 4:3 image can be 80" x 107" which is 8570 square inches. Whereas the 2.40 image will be the same 60" x 144" which is 8640 square inches.
Another advantage of this type of screen is that different resolutions can be projected at different image sizes. For instance because a 4K HDR Kaleidescape movie has higher resolution it can be projected larger. Whereas a DVD with lower resolution can be projected smaller if desired.
Take for example a 4:3 image from a 4K or 1080P Blu-ray which, for a certain viewing distance, might be most optimally projected as an 80" x 107" size image. Whereas for example a 4:3 image from a DVD, for a certain viewing distance, might be more optimally projected as an 60" x 80" size image.
For more information on the Stewart Filmscreen Director's Choice you are welcome to give us a call.
Note: This type of screen is optimally used with a high end projector that has a multitude of memory zoom and aspect ratio settings.
Perforated Screens vs. Non-Perforated Screens
However if due to room/system constraints the only way to implement the system is to fire the speakers through the screen then one approach would be to have selective "perfing", in which case the perfing is only in the region where the speakers are located behind the screen. HOwever the drawback to that is that most of the screened image will look better than the spots which are perfed for the speakers.
Another factor to take into consideration is whether the projector is a 1080P/2K or a 2160P 4K UHD one. At 4K the pixels are much smaller and the micro-perforations will interfere more with the image quality—whereas at 2k the micro-perforation interference will be less so.
Of course a high quality front (or rear) screen projection system that is properly designed and setup can present all of the above aspect ratios. At this point home theaters in which movies will be viewed are typically being setup with 2.40:1 aspect ratio constant height screens and then masking is used to present some or all of the other aspect ratios. However in some instances a constant width screen can be more appropriate if there is sufficient ceiling height.
If the system is going to use a projector and screen then ideally there should be an appropriate range match with regard to the aspect ratio of the lens and that of the screen.
There is of course more that could be said about aspect ratios, lenses, and screens. But once again you don't have to become an expert in all of the technical minutiae required to design a high end home theater. That's what we are here for.
With regard to flatscreen aspect ratios, there have been a few flatscreens that have been marketed as 21:9 which are designed to show full frame 2.39 aspect ratio movies. Just like a projection system, this means then that there is a constant height for all aspect ratios 2.39 and smaller. Plus it allows a video scaler to use an easily implementable 4:3 scaling factor. However 21:9 (63:27) is an approximation of the actual ratio which is 64:27. You might be interested to know that 16:9 is the square of 4:3—and 64:27 is the cube of 4:3.
For an 18 minute video on the history of aspect ratios in film with examples click here.
Then view this interesting video: On the Waterfront: A Tale of Three Aspect Ratios
Field of View
Note: The term "architectural cinema" is now being used to describe system/room combinations which are designed to a high level in every regard including FOV optimization.