Home Theater

How to determine BEST screen size for home theatre projector viewing?

I have a new projector and I’m looking to play HD dvd’s on it. Given distance X how would I determine the optimum screen size and dimensions?

Lacking the necessary information it would be nearly impossible for anyone to specify the “best” screen size for your specific application. There are numerous, often interrelated factors—some obvious, some not so obvious—that are involved in selecting the proper projection screen. If your projector has less than 1080p “Full HD” capability and/or lacks sufficient light output for your viewing environment, you may experience difficulty in obtaining the optimum (or “best”) screen size for your specific application.

Nevertheless, I suggest that if you prefer the simplest (though not necessarily the “best”) solution then you should skip to the bottom of my answer and use one or more of the projection calculators that I’ve listed below in order to quickly determine the best screen size for your specific application. Otherwise, if you are interested in the details behind selecting the optimal projection screen please read on and take the opportunity to read some of the resources that I’ve provided.

(Note: if you are using a 1080p projector then a 120-inch wide, 137.7-inch diagonal, 16:9 screen, as recommended above, will require that the closest viewer sit no closer than approximately 208 inches or roughly 17 ft. from the screen; and this distance will be even greater for a lower resolution projector! Furthermore, in a typical residential viewing environment most consumer grade projectors, under nominal operating conditions, are unable to produce sufficient light output to properly illuminate a high performance screen as large as 120 inches wide.)

In determining the optimal screen size (and projector) you would start with the more limiting factors such as the viewing environment – which includes room size, ambient lighting, and the maximum anticipated audience size and seating arrangement, as well as the horizontal and vertical offset of the projector.

Another important part of the process that plays a role in determining screen size is the field of view relative to one or more observers. The field of view is the angle that subtends the left and right edges of the screen relative to an observer (seated in a viewing position through which an imaginary perpendicular centerline extends from the center of the screen.) Assuming normal human visual acuity¹ the absolute minimum field of view for the FARTHEST seated observer is 20° (which requires not less than a 720p projected image); and ideally should be at least 30° (which requires not less than a 1080p projected image.) It is important to note that in an effort to minimize fatigue and discomfort the maximum field of view should not exceed 60° for the CLOSEST seated observer regardless of the projected image resolution. The basic rule of thumb is that the higher the image resolution the greater the flexibility you’ll have when it comes to laying-out your audience seating. Furthermore, if a person wishes to achieve the most immersive viewing experience the recommended field of view between the viewer(s) and the screen should be between 30 and 40 degrees approximately. Again, this requires a high definition display system that is capable of reproducing a full 1920×1080 or higher video image without exposing viewers to discernable picture structure when viewers are seated at the proper viewing distance.

Other important factors include: the source material (not all source material is filmed, mastered and/or encoded equally); the accuracy and effectiveness of video and image processing, whether from the projector, an outboard video processor, or a disc player; the lens throw of the projector; and of course your budget.

Also, when calculating the minimum and maximum fields of view you will need to start by choosing a screen aspect ratio that best matches the video content that you will be viewing. For example there is no point in purchasing a 1.33:1 AR screen if the majority of the content you intend to watch is encoded in the 35 mm “scope” or anamorphic (2.35:1 or 2.40:1 AR) format. So if you’re watching mostly movies from any of the optical disc formats then you may be best served by choosing a 1.85:1 “letterbox” projection screen. If you will be watching a mix of video source material then I recommend that you get either the widest AR screen (2.35:1) or the tallest AR screen (1.33:1) and use a “masking” system for those occasions where you will be watching content framed in alternate aspect ratios.

Once you’ve decided on the optimal screen aspect ratio then you’ll need to choose a screen type. You will want the best contrast ratio performance for your viewing environment and projector, along with the desired viewing angle specification and screen gain. In general the higher the screen gain the narrower the viewing angle. That said, I highly recommend that you avoid any screen gain greater than 1.3 otherwise you will begin to compromise the projected image fidelity. To quote the well-respected industry expert Joe Kane: “the ideal contribution of the screen to the display of information should be neutrality and uniformity.”

Da-Lite recommends a home theater viewing distance of six (6) screen heights for the last row of seating and two (2) screen heights for the first row of seating. (Note: two screen heights will likely result in visible picture structure to the closest viewer. Regardless of the viewing conditions a viewing distance of only two screen heights will require an image resolution of 2560×1600 or greater in order to avoid the annoyance of visible picture structure.) Nevertheless, once you know your seating arrangement, which is dictated in part by the room dimensions combined with the light output and resolution of your projector, you can derive the approximate height of your desired projection screen. At this point, depending on your choice of screen aspect ratio, you can quickly determine the desired width.

Also keep in mind that light obeys the inverse power law and—all things being equal—the longer the throw, as is required to produce an image on a larger size screen, the lower the screen illuminance. For the sake of comparison, the target white screen illuminance for “digital cinema” applications, as recommended by SMPTE 431-1, should be 14 fL (or 48 cd/m² = 48 nits) ±7% as measured at the center of the screen and not less than 80% of the center value at the corners and sides.

Since you already own a projector please be aware that, given the complexity involved in properly choosing an optimal screen and projector combination for a given viewing environment, you may very well require the assistance of a professional with expertise in projection screens or systems.

Hopefully whichever screen you choose will provide a good match for your projector and your viewing environment. As mentioned above you may find any of the projection calculators that I’ve listed below to be helpful.

############ RESOURCES #############

Digital Cinema Resolution

http://www.etconsult.com/papers/Technical%20Issues%20in%20Cinema%20Resolution.pdf

Image Quality for Home Theatre – Matt Cowan

http://www.etconsult.com/papers/Image%20Quality%20for%20Home%20Theatre%20Matt%20Cowan.pdf

Da-Lite Screen Company – Education

http://www.da-lite.com/education/

Interview with Joe Kane:
Display Screens – Revealing the Standards

http://www.da-lite.com/education/angles_of_view.php?action=details&issueid=36

Four Steps to Selecting the Right Screen

http://www.da-lite.com/dalitehometheater/products/selecting2.php

Angles of View – Resolution

http://www.da-lite.com/education/angles_of_view.php?action=details&issueid=34

Da-Lite Screen Company Multi-Mask Imager

http://www.da-lite.com/products/product.php?cID=20&pID=326

Home Theater Seating Guide

http://www.cinemasource.com/articles/seating_guide.pdf

Specifying Projection Screens in Six Easy Steps

http://www.cinemasource.com/articles/screens_six_steps.pdf

Types of Home Theater Projection Screens

http://www.cinemasource.com/articles/screen_types.pdf

THX Certified Cinema Design – Screen Placement

http://www.thx.com/cinema/builtTHX/screen.html

THX Home Theater Display Setup

http://www.thx.com/home/setup/display.html

THX Theatre Alignment Program Guidelines

http://www.film-tech.com/warehouse/manuals/TAPGUIDELINES.pdf

SMPTE Recommended Practice RP 166-1995, Critical Viewing Conditions for Evaluation of Color Television Pictures (Archived 2004)

http://www.in24p.com/in24p%20info%20files/SMPTE%20RP166-1995.pdf

SMPTE RP 98-1995 Measurement of Screen Luminance in Theaters

SMPTE Engineering Guideline EG 18-1994, Design of Effective Cine Theaters (Withdrawn in 2003)

SMPTE 196M-2003 Motion-Picture Film – Indoor Theater and Review Room Projection – Screen Luminance and Viewing Conditions

SMPTE 431-1-2006 D-Cinema Quality – Screen Luminance Level, Chromaticity and Uniformity

SMPTE RP 431-2-2007 D-Cinema Quality – Reference Projector and Environment

Digital Cinema System Specification, Version 1.1

http://www.dcimovies.com/specification/

Pytlak’s Practical Projection Pointers

http://www.kodak.com/US/en/motion/newsletters/pytlak/

To access the HTML versions of the documents use this link:

http://www.kodak.com/US/en/motion/newsletters/pytlak/oct2001.shtml

Screen size versus Optimum Viewing Distance

http://www.practical-home-theater-guide.com/Tv-viewing-distance.html

The right size (inches) TV for the room?

http://answers.yahoo.com/question/index?qid=20070830200739AANnIrU

Screen Size vs. Viewing Distance vs. Resolution

http://www.carltonbale.com/2006/11/1080p-does-matter/

Imaging Science Theatre 2000

http://www.widescreenreview.com/WSR_issue_ist.php

“High Definition Surround Sound with Accompanying HD Picture”
Relations of Listening and Viewing Configurations

http://www.tonmeister.de/symposium/2005/np_pdf/F04.pdf

About the “Ideal Viewing Environment”

http://www.cinemaquestinc.com/ideal_viewing.htm

Charles A. Poynton, “High Definition Television and Desktop Computing”

http://www.multimedia.edu.pl/invocom/MultimediaPL/txt/Poynton.pdf

High Definition 1080p TV: Why You Should Be Concerned

http://www.hometheaterhifi.com/volume_14_1/feature-article-1080p-3-2007-part-1.html

________________________

¹Based on empirical data derived from extensive research on human visual performance the accepted norm for human visual acuity for a person with normal vision is approximately 1 minute of arc (or MOA or arcminute.) Since no viewer should be sitting so close as to see the picture structure (such as individual picture elements, i.e. pixels or horizontal scan lines) then it is relatively straightforward to calculate a ‘no closer than’ limit for viewing distance.

Webvision Spatial Resolution – Visual Acuity

http://webvision.med.utah.edu/KallSpatial.html

###### PROJECTION CALCULATORS ######

Home Theater Calculator Version 3.6

http://www.carltonbale.com/home-theater/home-theater-calculator/

http://www.carltonbale.com/2007/07/updates-to-my-home-theater-calculator/

³Projection Calculator Pro – Throw Distance and Screen Size

http://www.projectorcentral.com/projection-calculator-pro.cfm

³Projection Calculator

http://www.da-lite.com/products/projection_calculator.php

³Projector Calculator

http://www.draperinc.com/Screen_Pages/ProjectionCalculator.htm

Vertical Viewing Angle

http://www.myhometheater.homestead.com/Verticalviewing.html

Viewing Distance Calculator

http://www.myhometheater.homestead.com/viewingdistancecalculator.html

Planar Systems Projector Calculator

http://www.planar.com/products/projectors/calculator/

Optoma Screen Size Guide

http://www.optomahometheater.com/content/calculator_index.htm

Screen Expert Advanced Wizard

http://www.screenexpert.co.uk/WIZARD/3/WIZARD3_start.asp

ProjectorPoint Screen Size Calculator

http://www.projectorpoint.co.uk/projectorscreensizecalculator.htm

Sony PJCalc!™ Projection Calculation Software

http://bssc.sel.sony.com/BroadcastandBusiness/markets/10007/software_download.shtml

³(Note: these are essentially identical Projection Calculators.)
 

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