Skip to main content

TTL Metering

Lesson 9 from: FAST CLASS: Understanding Light

Mark Wallace

buy this class


Sale Ends Soon!

starting under


Unlock this classplus 2200+ more >

Lesson Info

9. TTL Metering

Next Lesson: Studio Equipment

Lesson Info

TTL Metering

we're going to talk about something else here that is, um, loved and hated by everybody. And it's t TL metering and T tail metering stands for through the lens metering. I have a very scientific way of describing how this works and that is this. It's just stupid detail, Stupid, because, uh, our camera uses this is used the same, um, basic method for metering light for a long, long time. Now there are new metering modes that will help with this, but basically what the camera is doing, I want to show you this. Our camera will Actually this out is, um, look for something that is 18% gray, which is 100% wacky. So what's happening is a normal scene. If you take all of the highlights and all the shadows and all that stuff and you put in a blender and you mix it up when you mix that all that light together, what you'll get is everything averages out to about 18% great, which is a little bit brighter than these walls right here. They assume that everything in that scene is going to be 18% grea...

t. The problem with this is that your camera is really stupid. So what, We're gonna dio here? Yeah. Your camera is stupid. Is we are going to do a little test. And to do this correctly, John, I'm gonna have you come out. I'm putting my camera on an aperture value, got an aperture priority mode, and I have set my aperture to 4.5. And what I'm gonna do here is I'm just gonna zoom in to this white wall right here. Okay? So I'm zooming into the white wall and I'm going to take a picture of the white wall. Face me. There we go. I'm going to try not to see my shadow. I'm going to fill the frame. That's good. Right there. Taking the same picture right now. I want to show those two pictures side by side, and I think we're done with that. So we had a totally black wall and a totally whitewall I shot both of them. Let's look at these pictures side by side. The color temperature is different, but they're both gray. Both of them are great. And what happened was this white wall right here. The camera assumed that it should be grave and it was white. And so it under exposed it. It exposed it as a gray wall. And for the Blackwall, the same thing. The camera assumed that that black wall should be great. And so it over exposed it. And so it also came out Grey. So what I'm gonna do here is I'm gonna have mostly unless have you move about right there? Yes. Mostly white. Um, background okay. With are mostly white background. What's going to happen is we're having an under exposed lex. First thing I'm gonna do is fix the white balances by clicking on the background cause it was white, so we were able to do that. So sometimes you can use something in the scene to fix your white balance very, very quickly, which is really cool. Um, so the other thing we want to do, we can look at this, hissed a gram here and see how the history ram shows that the whites are under exposed. That should be much closer to the edge. Um, and so what I can do to fix this if I know that I have a lot of white in the background, I can use something called exposure compensation. And so I am going to tell my camera with exposure compensation, using the light meter inside. It's saying, Hey, this is what's exposed correctly. I'm telling it to overexpose intentionally because my camera is stupid. I'm saying, Hey, what you think is right is not right, so over expose that which is actually correct. So we're going to do the same thing I am over exposing this intentionally. So this here we're seeing much better exposure. So are 18% exposure is is totally wacky. And so we have to fix that. John, do we have the light meter? So there are two different types of metering. There's through the lens metering, which is what we just saw, and that is reflective meeting. So the light hits. The subject in the background, reflects off of that, and it goes into our camera's lens and, based on what's being reflected, the cameras trying to figure things out, and that's not the best way to meet her light. A better way is to use this. This is light meter, and it does incident light, metering and what it does, instead of assuming that this is white or black and averaging it degree. It actually looks the light that's falling on this thing. Here, this is called a Loomis Fear. And so what the actual light is coming in here? It doesn't matter if this is black or white or green or gray. It doesn't care. You'll get an accurate measurement on this. Let me show you really quickly. How are light meter and our camera works. So when our light comes through our lens, what happens is inside your camera there is this little mirror right here. And that mirror, um, is what S L. R stands for single lens reflex. So it's got this mere that that pops up. Um, So what this guy does is it puts the light into this thing called the Penta Prism, and that's how we see, like a little periscope. But some of the light goes up here and this light, this thing right here is where the T TL meter is. It's actually in the Pinter prism in the top of your camera up here. All right, so on this and I'll try to keep this a steady as possible. What we can do here is there a different modes on a light meter. And so what a light meter is built to do is to meet her, um, normal ambient light, but also lights from strobes. There are three things that are involved in the exposure triangle. They are I s O shutter and aperture. Correct? Yes. And so when we're using a light meter, we're gonna be shooting in manual mode because we're gonna We're going to set the isso, the aperture and shutter speed based on what this tells us. But we use this in a similar way that we would use our cameras, an aperture priority mode or shorter party. What I mean by that is the first thing you do is you tell your light meter what I s so your camera is using and so we're gonna shoot at an I S O who in here of 1600 because it's really dark. How do I know 1600? I don't I'm just guessing so 1600. So I'm gonna do is there's a little button here that says I s so I'm gonna push that, and I'm gonna set this all the way up to 1600. So this is going to stay there. So I need to set my camera to 1600 as well. And then what I can do here, under mode right now, I have this little tea that has a square around it. Can you see that? So it's got little t around it. What that's telling me is, why don't you put in the shutter speed you're using? And when you meet her, it will tell me the aperture value that I should use. Or I can go to the next boat, which is I'll put in the aperture value I want to use. And the meter will tell me what shutter speed. So you can do either one. So you set Theis so And then you put in either the shutter speed and it will solve for aperture value, or you put in the, I assume, put in the aperture value, and it will solve for shutter speed. So, Lex, we're gonna have you come out again, and we're going to take a photo. We're gonna use this light appear as the main light. And what you have to do is this Loomis, fear should be up. It can go up and down. Needs to be up and you need to point it to where your camera is. So I'm gonna be shooting from about right here. So I'm gonna point this to where my camera is going to be. That's very, very important. And this needs to be as close to your subject as possible. And so what I want to do it and push you to the side is I want to have this where her eyes are because her eyes are the most important for me from an exposure standpoint. But if I jabbed her in the face with this, that's no good. So I will normally do is I'll put this right underneath the chin because when I put it underneath the chin, noticed that this is now in line with her eyes. So I get the same distance and also putting out into the chin when you're working outside and natural light. Sometimes if the sun falls directly on Loomis fear it can give you incorrect values. So by putting this underneath the chin, what it will do is it will actually give it a little teeny bit of shade. And so you'll you'll save yourself the hassle. So I'm going to put you back this way. And then I am going to remember I'm not meeting into the light. Metering toward the camera is going to be. And so what I'll do is I'll take this point to where my camera's gonna be. I'll click the little button and this tells me 80th of a second is what I need to set my camera, too. So four point 5/18 of a second eso 1600. What if I wanted to be at the shutter speed of, Let's say, 125. All I have to do is push my S o button and change my I s o until my meter tells me 1 25 and it tells me Oh, I would have to be in an app on eso value of 2500 so you can just take one reading and then change one of the parameters to get it'll solve for the third. And so once you have that one reading, you have to do a bunch of like what if this one of this and so you can instantly take a reading and go, Oh, Teoh, have my shutter speed fast enough to shoot in this environment. I need to be Oh, that s o and off you go to the races, so let's try it. So this is at 25 4.5 So 1600 are 2500. Other thing with these guys, it is. Sometimes you have to calibrate your meter to your camera. And this one has not been calibrated to my camera. So it could be potentially off a smidge because every camera and every meter are built to slightly different variations or specifications. Which is why once you have your light meter and you calibrated it and got it dialed incorrectly, would you do with great card? You just keep it as your own. You never let anybody out of habit because it's perfect. Okay, so we're gonna try this. This is, uh, Lex. I'm gonna have you hold this for me. So the eso was 2500. So get that the shutter speed Waas 1 25 Is that right? And someone says 1 25 and the aperture value is 4.5. All right. And now we're gonna try this. I see it, see if it works. Perfect All right, now, this is awesome. Watch this out of the box, Boehm. Perfect exposure spot on there is like it's perfect. And so that's the joy of having a light meter is once you have it, it is perfect.

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