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Metering

Alright, it's time to dive back into the exposure concepts that we've been talking about, and I wanna talk just relatively briefly here about metering. Now, this was something that was really important back in the days of film, and that was because you couldn't see your results until you got your film back. And now, with modern cameras, we can see it on the back. It's kind of taken a backseat for a couple of different reasons, it's become quite easy. And so, this used to be a very daunting subject, and it's not something we have to dwell on too much here. So, if there is one thing that a photographer would like to know when it comes to the exposure is how much light is on my subject. And so, we used to be able to, and we still do in some cases, we'd take that little hand-held light meter, and we would walk up to our subject, and we would press the magic button on there, and it would tell us exactly the ISO, shutter speed, and aperture that we need. And you can still buy these light met...

ers, and they will enable you to get perfect exposures in every situation that you can actually walk up to and put a hand-held light meter in the tiger's face to make sure it's (audience laughing) illuminated correctly. So, it's a little impractical for a lot of things, which is why cameras have their own light meter. But it's a different type of meter, it's a reflected light meter. It's basing its information on light reflected off of that subject. It doesn't know what the subject is. It doesn't know what the light is. All it knows is the result of those two items combined together. Now, for good or for bad, these are all calibrated to middle gray. We're gonna forget about colors for the moment. It thinks, your camera, it, thinks everything in the world is an average of light and dark, this middle-tone gray. And in general, it's right. But in particular, it can be wrong about very specific things. So, if you take a picture of an object that is gray, you're gonna get a proper exposure from your built-in camera's light meter. It's gonna automatically do the right thing. Where things get, shall we say, interesting, is when you photograph dark subjects and light subjects. What happens is, with a dark subject, less light gets to the camera, and the camera, whose, has different divisions. The light metering division is like, oh, my gosh, this thing is really dark. And the camera's like, well, we better compensate for that and lighten this subject up because everything's middle-tone gray. And the problem is, is that, when you try to lighten that subject up, it kinda throws what that subject looks like, and the background, and everything else in the photograph, off. When you have a light subject, more light than average is coming back to your subject. The camera kinda freaks out, oh, my gosh, there's a lotta light here, we better change the shutter and aperture 'cause there's just too much light coming in. And so, that's where the camera wants to average everything out, so that your subject is normal. But it might throw off everything else around it, and it doesn't really represent the tonality of that subject in particular. So, be aware that you need to be observant of your subject. Is it lighter than average, or is it darker than average? And if so, you may need to make a little adjustment that I'm gonna show you here in a moment on your camera 'cause it may not show it correctly. So, if you're photographing polar bears out in the snow, you need to make a little adjustment on your camera. Now, the way you're gonna see this is usually through this light meter in your camera. This is how it looks on a lotta cameras. This is what's called a graphic light meter, and it's gonna have an indicator right in the middle when it is properly exposed. If something was overexposed by one stop, that line would move over to plus one. And if it was underexposed by two stops, it would be down there, minus two. Generally, they won't go beyond three in either direction. Anything beyond that, and you are hopelessly lost. But, so, you generally wanna get it started towards the middle. Now, some cameras try to do things a little differently, and so they have a numeric light meter, which is just simply a number. And it's gonna tell you zero, which means you're spot on, or you're overexposed by one stop, or you're underexposed by two stops, or all the various different settings within there. And so, take a look at your viewfinder. Take a look at your light meter in there, and see what it's reading for you. Now, the way that it reads this light is with a pattern. And there are different types of patterns that many cameras can choose from. Traditionally, center-weighted metering was what was very popular back in, let's say, the '60s, '70s, '80s, and so forth. And it was generally pretty good 'cause most of the time, your subject was near the middle, and it was heavily concentrated on the center of the frame. Then photographers wanted to get more precise, and so there is spot metering. And so, if you wanted to know how much light is being reflected by someone's cheek, you could put that little spot right on their cheek, and you could measure the light right there or in any particular thing that you wanted. And so, that can be a very handy, but it's a little bit more difficult of a, it's a very sharp kitchen knife that you wanna be very careful with in its use. And then came multi-segment metering. And I'm kinda simplifying terms here. And the idea here is that it's a whole bunch of spot meters and an algorithm, where it figures everything out, and it measures the light areas and the dark areas, and then it tries to really come up with a proper balance of what the correct exposure is. And I have to admit that the modern multi-segment meters are amazing. They are really, really good at judging what the correct exposure is. And so, for most people, they just leave it in multi-segment metering and just let it be, and it's, generally, if it's not perfect, it's close enough. And as much as I would like to tell you get the best exposure you can, which is absolutely true, exposure has a little bit of latitude. If you miss it by 1/3 of a stop or even a stop, there's a good chance that you're gonna be able to fix that in post production. And so, you don't have to be too hypercritical in most cases. So, we have our three different systems here. And you can play around with these other systems if you want 'cause they do have their place in photography. But for most people, this multi-segment metering system, which has as a variety of different symbols and is called different things. For instance, Canon calls it evaluative, Nikon calls it matrix, I think Sony calls it multi-segment. So, different companies will have their own little name for it there. And so, that's the one I recommend almost 100% of the time. Now, the reason that we're not spending more time on spot or center-weighted is because we have other ways of determining proper exposure in our camera, and that is what's known as the histogram. And so, when you take a photograph, there's oftentimes a Display or an Info button that you can press, and you get this little graph. And at first, the graph is, I remember when I first saw it, I'm like, what the heck is that? (audience laughing) I mean, I'm not reading the Dow Jones here, what's going on here? And well, this is a graph of the tonal distribution. It is showing you an analytical brightness scale of your image. And so, what it's doing is, if you were to think about all the pixels that you are recording from black to white, what the histogram does is it organizes all of this into a chart, where it has the black pixel off on the left-hand side and all the pixels of common tonality lined up together, with the white pixel over on the far right-hand side. So, by just looking at a shape, and remember, photographers are visual people, so shapes are really easy to read. You can look at the shape of this and immediately determine, is that a proper exposure or a bad one? Now, the graph that you're gonna see is based on 255 levels of brightness, okay? Over on the left are the darks, and then we have the shadow region, lotta mid-tones, and then over on the highlights. And so, you can look at this photograph, well, the histogram of a photograph, and you can say, alright, we've got a lotta mid-tones, there's a little bit in the shadow, very little in the highlights and the darks. And, while I can't give you an exact definition of what's a perfect histogram, this is a pretty good one. And the reason is, generally speaking, a mountain in the middle is a good thing. What you wanna be aware of is histograms that have too much information off to the sides, which means you got a whole bunch of really dark pixels or a whole bunch of really light pixels. But there's a lot of exceptions to the rules, so be aware of that. And so, in this, I like this one because there is nothing in the far-left column, which is pure black, and in the far-right column, which is pure white; which means I have captured the entire tonality of the scene in front of me. I've captured every pixel that is dark and every pixel that is light. And it has some sort of color information in there, which means it's not up against the walls. And so, if I wanna make this picture darker or lighter, I can do that in postproduction. There's limited corrections when you capture pure white and pure black 'cause it's very hard to change those. So, what you wanna look at is the photograph and the accompanying histogram. And so, this histogram is for this elephant. And you can see what an overexposure picture looks like and an underexposure picture looks like. And it's not so much that that histogram is particularly bad, but for that subject, it doesn't make sense. And so, when you are looking at your histograms, you need to look at your photographs, you need to look at the histogram, and you need to look at the scene in front of your own eyes and go, does this make sense? Where is this area of brightness coming from? Where is this area of darkness coming from? And should I make it lighter or darker? Now, with the histogram, you can change the shape of the histogram by changing the exposure. You can either brighten it up, or you can darken it. And so, this is, something about histograms is you can't push it in from the side. There's no squeezing and pulling it, okay? It's not taffy in that regard. But you can move it to the left, and you can move it to the right. And you wanna figure out, where is the most important information? If you're photographing your kitchen and you can see out the windows, do you wanna see what's out on the deck out there? Is that important or not, or is it okay to let that be blown out and be very dark? Or do you wanna see what's in the shadows, what's in the cupboards there? Depends on the style of photograph as to how you would change your exposure. So, the histogram is really what I consider the truth detector on proper exposure. And so, if you wanna know if you got the right exposure, look at the histogram. And if it looks good there, then you're probably good to go. So, I'm guessing that the colors we just saw with the blues and the yellows are yellows and blue tones showing up in the actual picture, but, I guess, how would you use that information to improve your photo with the actual, the actual colors we just saw? Right, and so, in some cases, you'll see a brightness histogram, which is just light like color, or you'll see an RGB, red, green, blue histogram, which will show you the different color channels. And if there was a color that was particularly important to you, you wouldn't want to clip it by having it too far off to one end or the other. With people's faces, the most dominant color is red. And so, you wouldn't wanna have the red channel clipped on the high end, and so having it all stacked up against the edge. You'd wanna adjust, so that the red channel was more towards the middle of that box.