# Studio Strobe Science

Lesson 16 from: FAST CLASS: Understanding Light

Mark Wallace

# Studio Strobe Science

Lesson 16 from: FAST CLASS: Understanding Light

Mark Wallace

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## Lesson Info

### 16. Studio Strobe Science

Next Lesson: Three Light Setup

Lesson Info

Studio Strobe Science

but I want to explain to you what seconds. And so, um, what seconds are a measure of the capacity of a flash? Much like, Ah, gas tank is a measure of how much gas a car can hold. It doesn't translate into how powerful that flashes necessarily or how powerful a car is necessarily what seconds say this flash construe ore this much power. And so generally the more power you can store, the brighter the flash. So that sort of works out. But those that electricity has to be translated into light. So what happens is when you plug your light in that energy is stored in the capacitor. So the watt seconds is saying this capacitor can store X amount, so 1200 watt seconds, 24 watts seconds. 500 seconds, whatever it is. But when you push the shutter release and trigger that flash, that power has to go through some circuitry. And that circuitry does some things, like trying to regulate the power in certain ways so that the color temperature is consistent and so that the flash illuminates the exact s...

ame amount every single time. There's a bunch of stuff that's happening there And then that flash tube translates that energy either into heat or light. The other thing that happens with, um, with that with the building up of your power is the recycle times. Like, how fast can a flash recycle and be ready to go? So these guys right here, if I set this at full blast, I'm going. Teoh hit test one to So it's about to something seconds right. 123 Almost three seconds to 2.5 to 3/4 seconds. Um, that's not super super fast, but that's a pretty darn bright light. If you had some higher end strobes at full power, you could go much, much quicker. But watch this If I take this and put it at its lowest power setting, which is still pretty bright. This guy right here, I think I can go. I think it will shoot at something to the tune of 10 to 15 frames per second, which is faster than most cameras can shoot. The other thing that is a consideration of different studio strobes is the consistency of the color temperature. And what happens is when the flash fires at full blast, you'll get a color temperature that's at a certain place. Usually it's 5500 Kelvin. That should also be exactly 5500 Kelvin when it's at the lowest power setting. And when you fire rapidly, it should be consistently at 5500 Kelvin or whatever that color temperature is that it should always be the same, no matter what power setting, no matter how faster shooting the color temperature should remain the same. This is the inverse square line. I'll move this so you guys can actually see it. Um, you guys are good at math, right? So solve this and s is getting, um I don't even know how to read that. Uh, So the inverse square law says this This is a law that says and on this read it to you. I don't know. An inverse square lies Any physical law stating that a specified physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity that what does that mean? So what that means is, it's describing how light falls off as it travels. So here's that works. If we look at our ah light source, and I've gotten so many emails about this. There's not a point source of light. I know. So we're gonna get over that and at one foot, if that's 100%. So let's say it's one. So 100%. If we go from one foot to two feet, how much less powerful is our light? And so a lot of people think well, if you double the distance, it's half is powerful, and if you double it again, it's half is powerful. But that is not how light works. In fact, it's inversely proportional to the square of the distance. So if we go to 22 squared is four. The inverse proportion of four is 1/4 to take four. You flip it upside down. It's 1/4. So this light goes from full power to 1/ power when the distance is doubled, and then when you go to three feet, it's 1/9 of full power, and it's exponentially dropping off. So this is sort of difficult to see, and all these numbers are just square. So five squared is 25 6 scored his 36 10 squares so that's where we're getting those numbers. So it's inversely proportional to the square of the distance. Okay, makes sense so far, all right. So let's talk about what that means in percentages, because this is where it sort of makes more sense. So the light at one foot is a 100% power. At two feet, it's 25%. That is a giant drop right, and at three feet it's 11% and then a four per scene. It's six. So between four feet and 10 feet, there's only a 5% change in power. So what that means is light work? Something like this. Something like this. Yeah, There we go. This curve goes totally powerful. Who and then it just sort of coasts.

## Class Materials

Bonus Materials with Purchase

Understanding Light Day 1 Presentation
Understanding Light Day 2 Presentation
Understanding Light Day 3 Presentation
Gear List
Zone Lighting Basic Setup

• Beginner