Hey! Hi. This page has been duplicated with updates at the Training Courses site: A Look At Light – Part II.
Please use this new site, since it will be the most up to date and it will come with new features. Thanks!
In Part 1 of the Contrast Lesson, a simple definition was introduced, with a few examples. Then you were requested to notice details in bright light and shadows while you live life.
Because there is a difference between what we perceive and what we are aware of. Your job as a professional-in-training is, 1) to learn how to be aware of things that you already perceive, then 2) how to communicate well when things are not as good as they should be.
We don’t think about it, but most of our vision is out of focus and not colored. Take a moment to observe: While you focus on this page, much of everything else is very out of focus, and most everything is greyish. You can still see movement if it happens – even in the out of focus areas. You can even tell the direction of a movement. [Sound is similar; while concentrating on something, non-important sounds get ignored, just part of the background, but an urgent noise will be noticed quickly, and with very precise location.]
We are constantly perceiving, even if we are not paying attention to something.
When our eyes blink, we rarely notice – but part of our vision went black for a while! How can we not notice that? When we see someone sitting at the table, we rarely notice the variations of color on their pants or their socks or their shoes. We glance and see the shoes as red. But if we look closely we actually see that the color might be dozens of shades of bright and dark red. If they are in shadows, that red is mostly dark, and some parts might actually be black.
The same shading is happening on the movie screen when you look at it…or at least it should be. If it isn’t, there probably is a problem. Your customers may not know what is wrong, but they will have a feeling that something is wrong. If it is irritating they may just not come back, even if they can’t describe it.
Sometimes you go in to check the picture only to get sucked into the movie and forget to stare at the dark or bright parts of the scene. These are the parts that will inform you if the equipment is working well. There should be detail in the bright – soft shades of colors – and most importantly, there should be exquisite detail in the dark.
So, trick number one. Don’t forget what you are looking for. Trick number 2…Look. Trick number 3: Become better at being aware of what you see…difficult at first but wonderful when you get used to it.
There is a technical way to measure light. If you promise not to laugh, we’ll tell you that it is based upon the light of one candle. All that stuff in Lesson 1 was true.
The term is candela and the measurement for the reflected light from the screen answers the question of “How many candles of light does it take to make the eyes perceive bright white.
The answer is: 48. 48 what? 48 candela per square meter.
Oh my. What is a square meter?
A meter is one of those obscure things for Americans, but very common every place else in the world. And, a square meter is even more odd. Let’s walk through this.
Put your arms out in front of you with your hands flat, facing down. Now, keeping your hands flat and at shoulder level, bring them toward the front of your neck and place the ends of your middle fingers together. Your arms make almost a straight line now. From elbow to elbow is about a meter. Some people will have a shorter distance, some a longer. Doesn’t matter for this purpose. Imagine that length at the bottom of the movie screen. Imagine the sides of a square going up the screen, but only for the same distance. The box with all those equal sides is about a square meter.
Imagine that only that square meter of screen will reflect light…the rest of the screen is dark and actually eats light.
Now, imagine a candle in a dark room shining on your square meter of screen. Put your imaginary candle one meter away from the screen. The light reflects back to you. That is one candela of light per square meter. And that, friends, is also Luminance. And luminance is what technicians measure off the screen with their fancy equipment.
And, if you want to be really cool, if you want to use the word that directors and cinematographers and colorists use, say ‘nits’. “Yeah; the screen is 48 nits…I saw them shoot it with the meter.”
Back to Contrast
Who cares? The picture is on the screen, the sound is hot, the popcorn didn’t burn this morning…all is good.
And maybe it is.
In a perfect world the contrast is the range or difference between what looks like white and what looks like black on the screen.
In most auditoriums, there is no real white on the screen or real black on the screen. There are many reasons for this, and it will always be this way. Even the most fancy DolbyVision, or Laser IMAX or Sony or Samsung LED wall doesn’t have as much light as a foggy day. But that is a lesson for another time.
There is a range that each room is capable of, and the equipment is in a war to try to make it stable …which it always loses. A bulb gets weaker, electronics get too hot or finds some other reason to fail. The screen material gets darker every week and month and year as it ages – and yellowish instead of whiteish – and sometimes computers just don’t talk to other equipment correctly.
Since it is your job to ensure quality, it is your job to decide whether contrast has reached a point of concern. So, it is time to learn how to judge it. Here are some examples.
When you see someone’s leg under a table or something in a shadow during a movie, you have an opportunity to “See Into The Dark”. At worst, you won’t even see that a black shoe isn’t part of the shadow. At best, you will see that there are different shades of black and grey in the shoe and sock and the pant cuff and the folds in the pants. Notice these things in real life, notice how there is a constant gradient in dark shadows, and how a colored floor will go off to black in the distance.
The opposite will happen in the brilliant whites and colors. There will be ‘blown out’ white where things are not distinguishable at all…just one flat and too-bright-to-look-at white. The funny thing is, the brightest that the very best projector and screen combination can create is 108 units of light, and most strain themselves to create half that.
[Remember from the lesson above: The standard is 48 candela per square meter, which again, simply means: the amount of light that would be created if you held 48 candles at a distance of one meter (3 feet) in front of the screen, then measured all the light reflecting from one square meter of the screen (which is about nine, almost 10 square feet).]
Outside, 100 units are nearly nothing. The reflection of the sun on a car is thousands and thousands of units. (Perhaps we should stop saying ‘units’ since we know that people in the industry call that unit of light a ‘nit’. Just don’t get confused when a tech uses an older term like Foot-Lamberts. 48 nits…48 candela per square meter is equal to 14 foot-lamberts. And yes, it was named after Mr. and Mrs. Lambert’s son. He was famous for a lot of things.)
On-screen, look at some bright part of the sky or something flat and nearly one color – a refrigerator, for example, or even a close up a white dog. The white should actually be many shades of white. You’ll see that this is true of a real dog, or a real sky, and the same is on screen: One solid, flat color is wrong (except in a cartoon!) A smooth gradient of white to lighter or darker white, or another color is correct. There will be shadows in the hairs of the close up of that white dog as well.
So, that is your task. Learn about Contrast by looking: What looks natural in real life and on screen. At first you will write to the tech and say, “In auditorium 5, it really seems like something is wrong in the shadows, but I don’t know what…it is better in the other rooms.” As your abilities grow you’ll be able to say, “The gradient in the darks is off in auditorium 5, they get muddy too quickly. The blues especially seem wrong…it seems like the yellows go toward the brown instead of toward the greens.” Won’t that be fun?
Do well and enjoy the ride.