Since there are many goals and purposes for this project, there are many things that need to be done.
Fortunately, they don’t all have to be done at the same time.
So, if you don’t have the organizational support to download DCPs onto a USB drive and get them into the Media Player/Projector system right now – you can still download some audio and light measuring tools, then experiment with them until you can use them easily in a dark room.
The twin article to this, about sound, is at: Do This First…An Evolving Story – Sound
Unlike the many free and easy to use audio tools for the iPhone, measuring light levels from the cinema screen doesn’t offer too many inexpensive choices. Don’t misunderstand, there are many that will measure light the way that a light meter does for a photographer, but we need one that measures the light bouncing from a screen.
Technically, measuring light from the light source…the projector in this case…is called measuring ‘illuminance’, while measuring the projector’s light that is reflected by screen is call ‘luminance’.
There is a screen company named Harkness which has developed a program for the iPhone named the Digital Screen Verifier. It costs $30. They write that the tool is made for cinema engineers. Hopefully that won’t scare you from using it. What they mean is that it is a professional tool. They don’t want people thinking that it is a toy. They can’t say it out loud, but they are rightfully impressed that they are able to get the iPhone to do so well and so consistently.
$30 is real money, and maybe we should say, “Just spend it. You are on the road to being a Pro, and a pro spends money on tools. Professionals also practice and they also speak to other team mates using the proper language.” On the other hand, even though the DCPs are made so you can compare blocks of white against black without a meter, the eyes have a hard time with absolutes. It is better to say to the tech that the luminance has slipped 6 candela, rather than guess and say…”Gee, it seems darker I think, maybe.”
You may get some arguments about using this tool from your tech team. Not because they don’t want you involved, but because the Screen Verifier wants to send its data to the Harkness Screen Archiver. Many people have a problem with your data being shared with someone outside of your organization’s computers. We have all read about the security problems with big stores and large websites, and we should imagine that small stores and small web companies also have problems. If you buy this program, just make certain to turn off the data export feature, or that you have permission to send your data to the Harkness database. And send Harkness a note saying that you want a method to send the data to your own web server if your team won’t allow external storage.
The other thing to know about this tool is that the measurement units are in an old format named foot-lamberts (abbreviated fL). The standard (worldwide) for measuring luminance is candela per square meter. It is best that you start your life as a professional with the proper words. You can even be more hip if you say ‘nits’, because that is what all the cinematographers use.
There is another reason for using the Standard International Unit (SI Unit). If you say to a tech, “It looks like we are 2 foot-lamberts different than last week, it doesn’t sound like much. 2 of anything doesn’t sound like much, and can be easily written off as pilot error. But when the standard brightness of an auditorium is supposed to be 14 fL, 2 fL is 1/7th or over 14% of the expected amount. Not a good trend.
On the other hand, since 1 foot lambert is about 3 and a half nits (actually 3.426), if the meter says 2 fL, that’s 7 nits (candela per square meter) – or more, out of the expected 48. That feels more like a reportable problem and a negative trend that needs to be handled.
Hopefully enough people will send messages to Harkness to explain why you want them to follow international standard…it isn’t like you don’t like Mr. and Mrs. Lambert’s famous son – he really was a fascinating person. Just explain that you only have so much time and learning the right way the first time is better for you. (Harkness email: email@example.com)
This is discussed in more detail in the Light and Color section (soon to be posted).
Make sure to write and yell at us for using maths. We won’t do it too often, and we just forgot this time. Sorry.