“Flat panels are great but if you need a display that is designed to provide a variable image over 98” (the current limitations of a flat panel) then projection is an affordable alternative to the more expensive dvLED.”

Those are the wise words of Alan C. Brawn, CTS, ISF, ISF-C, DSCE, DSDE. DCME, the principal of Brawn Consulting, in an article on display size in the March 2021 issue of Commercial Integrator Magazine.

Despite this, Brawn has seen what he terms a “disturbing trend.”

“With larger flat panel digital displays, designers have been unwittingly undersizing images & not paying enough attention to viewer distance,” said Brawn. “This is the tendency to take the path of least resistance and simply put in a flat panel display and call it good enough all too often irrespective of the viewer.”

One tool which Brawn points out as a way to avoid this tendency is the DISCAS standard. DISCAS, an ANSI standard adopted by InfoComm (now AVIXA) in 2016, stands for Display Image Size for 2D Content in Audiovisual Systems. It outlines formulas to use to determine screen size for both basic decision making (BDM) and analytical decision making (ADM).

In his article Brawn encourages the use of this standard to choose proper display size, and not leave it to habit. We heartily agree and have learned first-hand one key reason behind the difficulty of encouraging adoption of the standard.

“The DISCAS standard has not been widely adopted because it’s seen as complicated,” said Steve Cook, Consultant Relations Manager for Draper. “And our industry people in general don’t like complicated. They like ‘quick and easy’.”

There are also some other considerations that sometimes dissuade from the selection of a properly sized projection system and instead choose the wrong size flat panel display:

  • The desire to use the cheapest technology and spend extra on other items like furnishings.
  • Public projects (schools, courts, etc.) go out to bid, and will again go for the least expensive option (taxpayer dollars and lowest bidder).
  • The need to combine a larger screen with needs such as ambient light rejection, a brighter projector for larger screen based on square feet, and a brighter projector for the ALR screen.
  • A display for ADM does not fit the space.
  • The designer assumes almost everything is BDM and does not size for critical viewing.

Many in the AV industry have developed a so called 5:1 rule of thumb to determine screen size. However, the idea behind DISCAS is that there is a proper, scientific way to figure out “proper size” and get away from rules of thumb can lead to poor decisions and a negative experience.

We definitely encourage the use of DISCAS to determine and select the right size projection screen for your application, but we also realize that sometimes that will be a difficult prospect.

“Right now, if I were to say to use a rule of thumb, it should be between 4:1 and-5:1, depending on the use/mix and what will fit in the space,” Cook said. “But people should remember that these informal rules change over time by use and technology. They shouldn’t limit themselves. They may be locking into a display size that is too small and developing a habit of choosing the same incorrect size over and over.”

Draper has made it easier than ever to select a screen based on the DSICAS standard. Click here to use our Projection Planner 2.0 to choose the perfect size and viewing surface for your next project. Our planner does the math, so you don’t have to!

You can read the full text of Alan C. Brawn’s excellent article by clicking here.

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