Let's begin.

Hey!

Now, if you're anything like me and you're obsessed with lighting and how lighting works, then you've probably come across these terms.

Now, they're all related but not the same.

So, instead of me bombarding you with information, I'm going to show you this picture instead.

We'll be using this diagram to see where each term fits into.

When you look at a lightbulb packet, the first thing you'll see is the wattage.

Now, this is exactly how much power the lightbulb draws from your power socket.

More efficient bulbs can produce the same amount of light using less power, so sometimes the power outage has nothing to do with the brightness.

When the bulb converts electrical energy into light energy, it creates what we call the luminous flux.

Now, if you don't know what the term flux means, don't be scared.

Flux is just a made-up term that we use to sort of describe the flow of things, in this case, the flow of photons.

In other words, luminous flux is the total amount of visible radiation the lightbulb gives off, and it's measured in lumens.

This is typical of lightbulbs that you see around the house.

It'll have a lumen value.

The higher the lumens, the more light it produces.

Now, if we took a section of that light and measured how much light is in that section, we would get the luminous intensity.

Wait, what?

Then isn't the luminous flux and the luminous intensity the same thing?

No, dummy.

Household lightbulbs light up a very wide field.

In commercial lighting, it's more directed light.

So, in commercial lighting, it's actually very important to look at how intense the beam of light is going to be instead of looking at how much light is produced in total.

So that is why we use luminous intensity.

Ah, gotcha.

Good.

Let's move on to illuminance.

Illuminance is the actual amount of light that actually hits a surface.

In other words, how illuminated the surface becomes.

But before we continue, it's important that you don't get the term illuminance and luminance mixed up.

They sound the same, but different.

Remember, illuminance is the amount of luminous flux that actually hits your subject.

In filmmaking, this is very important because you want to know exactly how well your subject is lit up.

And illuminance is measured in the unit's lux.

But one thing that you have to keep in mind is that the lux value will change depending on how far your subject is from the light source.

Because the further you go away from something, the less illuminated it becomes.

So commonly, when you look at lux values on lighting equipment, it will specify the distance at which it was measured at.

Alright, next.

No, I'll be running the show here, thanks.

Moving on.

When the light hits the subject and reflects off of that subject, it creates what we call the luminance.

Now this is what the cameras and our eyes pick up.

And it's measured in nits, remember?

Or candelas per square meter.

Remember in my last video how we talked about how the iPhone had 800 nits of brightness?

Well, that is the luminance.

Just from looking at this diagram, we can actually see that lighting is a multi-step process, and that's why we have all these complicated terms and all these multiple terms.

So it's very important which part of the lighting process you are most interested in, and using that measurement to making the best decision.

One thing to keep in mind is that the word brightness cannot be used when measuring things, because brightness is subjective.

It doesn't actually have a value to it.

Well, there you have it. A quick look at what the terms and lighting mean.

I hope you learned something new, or at least found something useful.

If you did, then yay, thumbs up to you.

Thank you for watching, and I'll see you in the next video.

Microsoft Mechanics www.microsoft.com