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Overpowering the Ambient Light

Lesson 4 from: FAST CLASS: Speedlights 101

Mark Wallace

Overpowering the Ambient Light

Lesson 4 from: FAST CLASS: Speedlights 101

Mark Wallace

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Lesson Info

4. Overpowering the Ambient Light

Next Lesson: High Speed Sync

Lesson Info

Overpowering the Ambient Light

we have three things that we can adjust here. This keynotes gonna come up here. So for the ambient light to make it darker or brighter, I'm using exposure. Compensation. Well, I'm doing is I'm taking the exposure compensation on my camera, and I'm rolling it up or down. Okay, If I want to change the flash output, I'm using the flash exposure compensation, which we haven't got to. Now an icon. Owners, I have this whole thing here that says Don't be frustrated. The reason I don't want to be frustrated is this doesn't work on like on cameras. This doesn't work. So the reason it doesn't work on a Nikon camera. If you use exposure compensation, what will happen is everything will get darker, for everything will get brighter. Okay, There isn't a separation between the ambient light and the light from the flash. So Nikon owners don't get frustrated by this. I'm gonna show you how you can do that on a Nikon and work just fine. But for now, the stuff that I'm showing it doesn't really work on a...

Nikon camera. So what I'm doing and I'll do it again. I'm gonna take my aperture this time I'll put it down to I said it to 11. Okay, Much smaller aperture, some controlling the ambient light. Much, much more. So I'll take a picture here. My exposure compensation is at nothing. It's at zero. Okay, you could hear that really slow shutter. And these are horribly composed, by the way, cause I'm trying to make sure I get ambient like So this is gonna pop up here. And when it does, you'll see that we have this bright light exposure compensation. What I'll do is I'm gonna roll that down by negative, too. So I'm saying, take what you think is the right exposure. Stupid camera. And under expose it by two stops, it's only going to affect the ambient light. Okay, I'll explain what that is. Later. That was my So I do that now. Watch what happens to this wall here. When this next shot comes up, you'll see this goes from a light grade to a really dark gray. So just rolling my exposure compensation. I'm able to change that. So the inverse square law works like this. What it says is that light coming from a flash or anything as soon as it comes out. It just drops really, really, really fast. And so I'm gonna diagram this out. So the inverse square law says that light decreases inversely proportionate to the distance of its source. Don't quote me on that. What that means is if I have a uh, sorry. This is a flash things a flash, a flash. And I have a subject right here. There's a little line. This is zero feet. This is one feet two feet, four feet, eight feet, 16 feet. This isn't to scale, but you get it. Do we go over 32? 32 feet? Okay, let's pretend that this is to scale. Just go with me on this math people. Okay? So at one feet one foot right here, this is 100% power. Very, very bright. Okay, Now, inverse square means that if we square to two times two is four and then we invert that so two times two equals four. We invert that we get 1/4 so we go from 100% down to 25%. Is my math right? Hey, failed math. Okay, so we just lost from one foot to two feet we just lost 75% of the power of the light. So light when it comes out just goes that, like an eighth grader doing chores, right? Just, uh, now, I don't know. I thought Okay, when we get to this four squared is what 16? Okay, that's a faras I'm going to just given to me from there. Okay. 1/16. Which is what percentage? Six percent. Wow. Went from at two feet, 25% 4 feet. 6%. Eight is what percent? 2% in the rest of wining. Saying 1%. We're rounding these math people. So you see, what happens here is the flash goes from here. Down evens out. It makes that noise to, um So the flash, the farther you get from the flash with less power you have, and it just sort of goes down and then sort of plateaus right here. So what is happening is if I have my flash and I have a Sarah right here or if I have a Sarah right here, the output of the flash is pretty much the same in this realm of distance from the flash. So if I have a wall right here. The wall and the subject are going to both be exposed about the same. They're gonna be about the same. Which is what happened when we had Sarah against this wall with the portrait is when the flash went off. I can't really control the wall. The ambient light exposure on the wall separate from the light on Sarah because most of that's coming from the flash. And it's about the same exposure as opposed to the other way. We had these big windows and say these air windows Pictionary, uh, Sarah was up here. So what we're able to do is this light right here is much more powerful than the light coming in from flash back here. So I'm able to separate this, and this is ambient light, and this is like from the flash. So it's something you have to really be aware of when you're shooting a subject is how far away is your subject from something else behind it. If you want to control that, because if there close, you won't meal to separate those two things, you need some distance. Two separate. Let's first talk about some things that ambient light and light from our flash have in common. Okay, so we'll look at these two things, and I think some of the pictures that we just shot help It will be like, Oh, got it. Okay, so number one I s so we know that if we change the eyes so it will change how much light comes in both from the flash and from the, uh, the ambient light. So this controls both. The second thing is the aperture. So by closing down the aperture weaken, restrict light that comes from our flash weaken. Restrict like that comes from the ambient light. Okay, so these two things will both impact our exposure. The shutter controls, ambient light and the flash output controls of flash. So when I'm in aperture priority mode, what I'm doing is I'm setting the aperture and the I S O. And the shutter is being set for me by the camera. And so when I say, let's say this shutter is said it 1/100 of a second. And I say I want to use exposure compensation to make the ambient light darker. This shutter is getting faster. Okay, that's what's happening. This is getting faster, so all of the ambient light is going down and this is staying the same. If I change the exposure to, say, mawr ambient light, this is getting slower, more light comes in and this all stays the same. So what I like to do is I want to dial in my ambient exposure first. That's where you want to do in a dialing. Ambient light. First on and remember, there's this important thing here, and that is that the ambient light can be included or excluded. You can included or excluded.

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