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IMAG Michael Scott
IMAG options include what is shown here at Henderson Hills Baptist Church in the church's worship space.

IMAG Systems: Viewing Video from the Back Row

As a society, we have become accustomed to viewing screens on a regular basis, and live video is a method of better conveying emotion than printed news.

A lot has changed since the dawn of media, and how information is conveyed. It wasn’t that long ago where we had newspapers that were seen as having an immense amount of ability at getting the word out. Today, though, that has changed, to where people have become attuned to a nearly instant news cycle, one accessible across the globe.

Today’s screens have ranged from a smartphone to a TV set to a projector and screen or an LED video wall.

As a society, we have become accustomed to viewing screens on a regular basis, and live video is a method of better conveying emotion than printed news.

Therefore, you ask, what does the newspaper have to do with IMAG? And just what is this thing you call IMAG?

Image MAGnification is what it is. Just like you can take a microscope and use it to magnify something particularly small, a growing way for a pastor to convey their message to their congregation, is to use a camera system along with a screen.

Today’s screens have ranged from a smartphone to a TV set to a projector and screen or an LED video wall.

A few of the topics that need to be considered when using a screen to magnify your message include:

  • Screen size vs. viewing distance
  • Screen brightness vs. room ambient light level
  • Color accuracy
  • Latency
  • Viewing angles
  • Camera and video capabilities

Let’s jump into to each of these topics, and discuss why they are important…

Screen Size

This has been a topic of discussion for decades, as if the screen size is not large enough, then you have no actual MAGnification. What ends up happening is just duplication of the image, which in my opinion is distracting. Years ago, I learned the 4-6-8 rule of screens, and in the most basic sense, it was a multiplier of screen height for the furthest viewer from a screen.

You would use four times the screen height for the furthest viewer for highly detailed content, on a screen where you may have spreadsheets or other data displayed using a small font, and then six or eight times, based on the lower detail content.

In most every church setting, we are at the eight times screen height, and at times, have gone as far as 10 times. For example, let’s say you have a 10-foot tall screen, this would put the furthest out viewer at about 80 feet.

Screen Brightness

In the case of video projectors – the most valuable thing to note is that you need enough lumens of brightness to fill the screen, and it is directly proportional to the size of the screen. Here again we have formulas that are applied toward a general rule.

Starting with a darkened room, I strive for 40-foot-lamberts, or ftL (a unit of luminance). For a moderately bright room, 60-foot-lamberts works well, and in a bright room with a lot of ambient light, it would need at least 80-foot-lamberts, if not significantly more.

How do you calculate lumens to foot-lamberts? It’s pretty simple, you take the screen height, multiply it by screen width, to get your square footage, then you divide the lumens by the square foot area of the screen. For example, a 16-foot wide by 9-foot high screen is 144 square feet. and if you multiply that by 40 (ftL), you end up with 5,760 lumens needed in a darkened room. Then a medium lit room would need (144 square feet X 60 foot-lamberts) 8,640 lumens, based on the formula. For a bright room, that would calculate to an amount 144 square feet by 80-foot lamberts, totaling 11,520 lumens.

Now all these calculations ignore other aspects, such as losses in lamp brightness, lens losses and other things, so you would want to round up in your projector selection, for each scenario.

Color Accuracy

This is something that is generally overlooked in a purchasing decision for a projector or other display device. And simply put, not all projectors or displays are created equal, nor do they all offer excellent color accuracy.

I have seen many projectors struggle with color brightness and accuracy, to the point where something that should be red, ends up looking brown at best. If you are planning to have your pastor shown on screen, he or she should look natural, and have good color rendition.

Latency

This can add up to an ugly thing when working with IMAG. Imagine your pastor being animated with lots of movement during their sermon, only for what is being displayed on the screens being so delayed, that any movement being rendered, make it look you are watching a bad kung fu movie? This is an area where different display devices have a differing amount of latency, in their ability to show content. Consumer grade TVs, for example, tend to have a fair amount of latency, unless you enter them into “game” mode. Projectors all have some latency, as do LED video walls.

Some of the testing that I’ve done on various LED walls have shown at times in excess of seven to eight frames of latency. In other cases, it can be down to just about two frames. This will have a substantial impact on the ability of the IMAG system to operate in a seamless and distraction free mode.

Viewing Angles

This is a topic of both a screen’s ability to show content, as well as placement of a screen within the sightlines of your audience.

First off, there are projection screens that have “gain” – which is the ability for the screen to magnify the brightness of the projector, but the drawback is the limited viewing angles that the screen will do this. Once you have left the sweet spot, then the screen brightness is far less than what a nongain screen would look like. So a careful selection of screen material is very important.

Secondly, there are LED video walls that have issues off axis, when viewing the content. Some models have a very consistent image as you view them from the side, so doing careful evaluation of whatever screen you plan to use is important.

Next, let’s shift gears to discuss audience viewing – one factor that is commonly missed, working to keep the screen itself within a comfortable viewing distance and angle from the primary focus of the stage or altar area.

There have been many churches, where in order to see the screen, you need to physically crane your neck around to see the screen, where an ideal situation would be a quick shift of the eye to see the screen. Keeping the screen within a reasonable line of sight is important.

Camera and Video Capabilities

With this topic, it needs more time and space than is allotted for here, but I’ll touch on it. With the advent of new LED lighting and the very narrow band of colors that they can broadcast, some cameras don’t properly render the colors as seen by human eyes.

The most common color where this could be an issue, would be a magenta that appears blue on the screen. Latency can also add up along the video chain, so just be aware of the needs of your video equipment that is supporting the screens.

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