Joel Rollins: Do the Math

By Joe Rollins

For several years now, I’ve wanted to locate Mr. Zeminicki from my high school, and apologize to him.

Mr. Z was my nemesis, the math teacher who taught algebra and trigonometry. I was the long-haired student who constantly argued that “people don’t do this in the real world.” He was the teacher who endured the slings and arrows, and patiently gave me my C+. Thanks to the miracle of Google, he’ll probably eventually see this article, assuaging my conscience that I’ve never made the call.

Mr. Z, I’m sorry. We do this math thing every day. In fact, we live and die on it. Sometimes literally, when we’re talking about rigging safety or electrical load calculations. Often, it’s just our pride or our professional reputation, like the times I’ve seen sets being cut up outside the loading dock because they were designed too big to make some corner in the load-in path. Or when we see a projector backed up against the wall, unable to fill a screen by a few inches.

And yet, it seems to be a dying art form, this math thing.

When I got into the business, fixed focal length lenses were the norm – so we quickly learned all the formulas (formulae?) for calculating throw distances and screen sizes. Sound systems were more basic, and much less powerful, and much more analog. So we learned to calculate coverage areas and delay specs. It wasn’t a high-end art form only the CAD guys did it. It was a basic part of the business that had to be done for all setups. It has always been a basic part of AV training, and is something that I and most of the other InfoComm Academy instructors have always emphasized. In fact, Scott Wills, now the (check title) at the InfoComm Academy, was the Service Manager at the first AV company I ever worked for, and he was one of the guys who managed to beat some of this stuff into my head.

So, when I teach, I’m constantly shocked that lots of newer techs seem to have a problem with doing the math. Most resort to manufacturers’ tables for products, lens slide rules, and fudge factors. Or, when forced to do the problem, they tell me that they would normally just go to a senior person in their company, some “brain” who would always give them the answer.

But most never get the connection that this, the understanding of some basic math and geometry, was one of the reasons that person wound up senior. And that probably, like me, they just rely on a calculator and a dog-eared copy of “The Backstage Handbook” to arrive at those answers.

So, to the many entry-level technicians who subscribe to this newsletter, let me give away a secret: The people you report to are working with some very basic math. You can do it. And it’s part of what separates the amateurs from the pros.

Thanks, Mr. Z.