Artistic Intent – Why We Are Here
The Producers and Directors all believe that if they make their vision come to life – make the story into a movie – it will be shown in a way that makes the audience see and hear what they created with the same splendor they created. Were they wrong?
Quality Management Basics
If something is managed properly, then there is control over the quality of the items being delivered, and assurance that the end user will be satisfied. Quality Management | Quality Control | Quality Assurance
- Ideas Behind The Checklist
- Routines to Self-Certify – Checklists and Employee Training – Part I
- Routines to Self-Certify – Checklists and Employee Training – Part II
- How to: Manager’s Walk Through
- How to: Manager’s Walk Through – Part 2
- Units of Measurement
- Where to Judge The Auditorium
- 3 Letter Acronyms – KDM, CMS, FLM and more about Encryption
Cinema Basics – Audio
Some say that a movies sound is 50% of the movie. So, it better be good, eh?
Cinema Basics – Picture
Sound has nuance. Picture has a thousand words for nuance. Let's learn some.
Your picture and sound equipment get calibrated according to a schedule that management thinks is appropriate for your facility – sometimes in 6 month or 12 month or 18 month intervals. But we all know that things happen in between. With the right tools, you can become the judge.
Some of our customers use the large speaker systems to know what the actors are saying, some read the words with special "closed caption" equipment...some listen to special tracks on headphones. The equipment is called Accessibility Equipment. We have to understand it and test it to make certain our customer gets the best experience possible.
- The Other-Abled, and You
- Accessibility To Inclusion In Cinema – Prelude
- Promise, Promises and Great Expectations
- The Access Community
- Accommodation, In General
- Accommodation, Open Captions
- Accommodation, Closed Captions
- No Technology Before Its Time
- Industry Coordination
- Different Paths; …and Finally, Results
- DCP Production – Narration and Closed Caption Creation
- Currently Available – “Personal” Closed Caption Solutions
- Specialized Audio Systems for the Blind and Partially Sighted
- Signing In Cinema
Life happens in real time. Sometimes we read about it. More rarely, we are there. And after, we wish that we could have practiced a little bit before being thrown into it.
Units of Measurement
This lesson about measurements might get a little technical, but we will try to keep it light.
Remember that saying from the baseball player Yogi Berra? He said, “In theory, there is no difference between theory and practice. In practice, there is.” We find that is true all the time. In theory, 10 minutes exists. 10 minutes and I’ll be done with this! Give me 10 minutes, then we’ll go. In practice, it is always 12 or 15 or more minutes. 10 minutes doesn’t really exist.
In theory, you don’t really need to know each little thing involved in the measurement of sound and light, or why the engineers expect (and respect) the terms.
In reality, the little things can leave us in a swimming mystery if a word or concept seems important but we can’t grasp it.
So, let’s do some grasping – just enough so that we get enough information without diving into the confusions of the internet.
There is a group called the International Organization for Standardization, which most people call the ISO. As you can guess, they organize standards. Other groups bring standards to the ISO, standards about fire safety or electrical safety. For our industry, the Society of Motion Pictures and Television Engineers (SMPTE) develop standards and bring them to the ISO for worldwide implementation.
The ISO also organizes the most basic of definitions. It has been decided that there are 7 basic units of measure, and everything else can be derived from them. These International Standard Units are abbreviated as SI Units, and they are:
|mol||mole||amount of substance|
You don’t need to know much more than that for most of these.
You can go your entire life without using the mole unit, even if it is fun to think that there is a single number that scientists use for counting the number of atoms in a box. In the same way, only people in a special part of the science world use the Kelvin scale – although, many people use the Celsius scale which uses the unit of degrees in the same way (except that 0 in Celsius is the temperature that water freezes at, and 100° C is the point that water boils. In the Kelvin scale, 0 Kelvin is the coldest of cold that nothing can go colder, which is called absolute zero.
Most people will also know what a second is, and we should all be glad that a second is accurately defined and everyone uses the same definition around the world.
In the cinema auditorium we will use the second since sound travels so many ‘lengths’ of distance every second. That length is usually called a meter, and sometimes spelled: metre. Some countries – well, one country, uses the length of feet, which is about 1 third of a meter (or one meter is a little more than 3 feet). Sound travels at 383 meters per second. That is pretty fast. Most auditoriums are not that long. So, the sound from the speaker gets from the speaker to the audience in less than a second.
But the speed of sound is nothing compared to the speed of light. Light goes almost 300,000,000 meters per second – 3 hundred million meters every second! For our purposes, that is instant.
Ampere is something that is used every day in the cinema projector room, but we usually call it ‘amps’. The projector bulb uses energy to create light. That energy flows through the cables from the wall and into the lamp from both ends. Somehow – by magic possibly – the gas inside the lamp gets charged up enough to emit light. Not just any light, but the frequencies of light that can be used to light up some magic mirror chips that bounce the colors that show up on the screen.
You will learn more about frequencies in the lesson called: Audio (Sound Basics): Part 2.
You will learn more about these magic mirror chips in A Look At Light – Part 1.
There are several reasons that these bulbs become less efficient at converting electricity into light. Usually it is that the ends of the sparking parts inside get corroded. In this case, corroded means that they eat themselves up. The pointy tips get pits and the pits make sparks that go different directions instead of strait to the other pointy part. That means they need to consume more energy to make up for the electricity that goes sideways instead of strait.
More energy – we measure the amount of that energy as so many ‘amps’. When the bulbs brightness gets weaker as it ages, we have to increase the amperage, or amps.
There are two more Standard Units that we are more familiar with, even if we don’t use the words all the time; kilograms and candela. We use kilograms every day, because it is the unit of measure for weight. Even in the United States where they still use pounds and ounces, everything from breakfast cereal to computers and TVs also have the weight in kilograms or grams on the box. Of course, speakers have weight and movie screens have weight, so we have floors that are designed to hold these weights safely. Since these things were decided years ago, and don’t change, we don’t have to think about it much.
Candela is really the most interesting measurement for us. Up above it is called ‘Luminous Intensity’.
‘Luminous’ is a neat word that comes from the Latin word for Light, which is lumens. Candela comes from the Latin word for ‘candle’, which creates light. But in the world of standards they don’t just use any candle. The ISO specify it so that anyone, anywhere can create the exact same light if you happen to have a wick made out of pure platinum and a certain amount of the exact wax.
‘Intensity’ is also an interesting word. It hides a sophistication that we need in our work. The word Intensity is used to describe the strength of something, but it is best when we use it with “per unit” of something. For example, speed intensity might be described as Kilometers per Hour. In our case, Candelas deal with the strength of the light we are using. The ‘per’ that we will use is part of the screen size. In the old days, they used ‘square feet’. They measured the amount of light that fell on a 1 foot x 1 foot square of the screen. Now, we use meters, so we say Candelas per square meter.
The abbreviation of Candelas is ‘cd’. The abbreviation for ‘per’ is the slash sign: ‘/’. The abbreviation for square meters is an ‘m’ with a little 2 placed behind and above it. So, for 10 candela per square meter we write: 10 cd/m2.
To understand the sophistication of this better, let’s look at this picture.
Hmmm…must find that candle drawing.
To understand this better, let’s look at this picture. First, we see that the energy from the burning wick is leaving the candle in all directions. Instead of energy coming from a wall, the energy is coming from the wax of the candle. The energy of the wax is being converted by the fire, and emitted into the air as heat and light.
Can we ignore the word ‘Flux’? No? OK. Let’s just say that comes from the Latin word for ‘flow’, with an example of a river flowing, or air flowing. In this case, light is flowing, or a science person will say, lumens are flowing. But what is the intensity?
Some of the light hits the ground with enough intensity to see or measure. Notice that, even though the ground is bright, the ground is not creating light. It is receiving light, and if someone wants to measure how much light it is receiving, we call that light ‘illuminance’. Professional photographers do this all the time. They put a meter next to a persons skin and measure Lux. Of course, they are also interested in the light coming into the camera. But before that, when they are measuring the light on the scene, they measure the effect of their lights in lux. Lux is an abbreviation for lumens per square meter.
Lux and Illuminance is not something that we deal with in the cinema. We deal with ‘Luminance’. Luminance is the light being emitted from something that is being received by the eyes (or the camera).
In this modern age, this has two uses. One is the light being reflected from the screen. The other is the light coming from the giant LED walls that some cinema theaters are putting in. That light – the light getting to the audience – is the interesting amount for us. Luminance. Candelas per square meter.
So now, after many definitions, we can sum this up.
In the cinema, first we have the energy from the projector. That energy leaves as light, and differently from the candles light, the projector’s light flows from the lens in only one direction. Because it is flowing from the source, it is called – everybody say it – Luminous Flux.
The amount is called – Luminous Intensity. When intensity was coming from the wall, we said that we measured amps. Sometimes you will see this measurement called Watts. Watts is not really a measurement of light output. It is named after James Watt, a person who studied the power of steam in the 1760s! …no association with light. So, don’t let people confuse you. Watts is power, at the time, measured in horse-power. And watts is a subject for another time.
Luminous Intensity is measured in – everybody, all together – candela per square meter. All the hip cinematographers will never use that many words. They will say: ‘nits’.
If we stand at the screen and point a meter into the projector lens, we are measuring – everybody? – Illuminance. Illuminance is Lux. We don’t do that. It hurts the eyes!
We cinema people point our meters at the screen. We measure light that is reflecting from the screen or light that is exiting from the screen full of LEDs. We measure this because we want to know how much light is going to be received by the eyes of our customers.
This article is a Work In Progress – more soon.
This lesson is still a work in progress. The following needs to be incorporated:
|Contrast Ratio||Ratio||measurement – part of a nit|
|10||100 nits to 10 nits||–|
|100||100 nits to 1 nits||1 nit is a 1,000 millinits. That makes sense, right?|
|1,000||100 nits to 0.1 nits||100 millinits|
|10,000||100 nits to 0.01 nits||10 millinits|
|100,000||100 nits to 0.001 nits||a thousandth of a nit – a millinit!|
|1,000,000||100 nits to 0.0001 nits||a tenth of a millinit!|