Shooting Workflow: Histograms and Exposure
We're gonna talk about shooting workflow, and specifically histograms and exposure, 'cause that's a tricky part of digital that is quite different than film, even though most of us haven't shot film in forever. It's much more complex than it was with film. Film, you just throw a light meter up there, it tells you what it is, and bam, that's what you do. Or you trust the meter in your camera, or you experiment a bit, or you basically bracketed shots to make sure one of those was the right exposure, and these days we don't have to do that anymore, because we have this meter on the back of the camera called the histogram that's telling us everything we need to know. So let's get into this a little deeper here. How do you figure out what the best exposure is? My answer to that question is use your histogram. So on the back of the camera, your histogram will either show up as, here I can come out here so you can see this. This is how I have it set up so you can see the average, the red, gre...
en, and blue, but you can also go to a place like that where you just see an average histogram. That's kind of a funky looking histogram, but you get the idea. There's all kinds of different settings. I just wanna show you that that histogram on the back of the camera is probably the most important thing on the camera besides the sensor and the lens, because it's gonna tell you whether you blew it when you took that last picture. So to talk about histograms, on your right. First off imagine, basic math, the bar graph. This is essentially a bar graph except they took all the spaces out between the graph, the bars. So on your far left here is your shadows, and so that would be pure black all the way over here. And on this side would be pure white. Doesn't really matter how high they go up or what it looks like in the middle. You don't care, that just describes the image. So don't worry about that part. Other little tricky thing, and this is getting super geeky on digital sensors. They see differently than our eyes do. They see differently than film does. In the old days, I'll just draw a graph with my finger, if this is X, Y, we drew an S-curve like that, so there was a little bit of rolloff in the highlights and the shadows so that film saw like our eyes did. In digital, it's a linear device. So if we draw a graph, X, Y, it's just a straight line at 45 degree angles. This is twice as bright as that. That's three times as bright as this. There's no alteration for the way our eyes see, so that's a little bit different. There's also, let's think about from this pure white to pure black, and in this example here, let's just say our camera has six stops. So one stop is F4 to five, six. or 1/120th of a second to 1/250th of a second. Most cameras these days have anywhere from 12 to 15 stops, depends on the camera you have, so this is definitely just an easier way of describing this. If there's six stops and this means an eight bit, there's 4096 colors per channel. Forget about that for a second. We're just gonna do it in black and white. What that means is the first half of that chunk is half of the data that your camera can record, so in the brightest part of the image is where it can record most of the information. As you go down to the pure blacks, if you've got a six bit camera, only 64 data points are from that last little tiny sliver of information here. So I know that's kind of confusing, but what that means is if you underexpose your image, you're throwing away huge amounts of data that the sensor can record. So that adjusts how we think about exposing for our image, because we're not doing it according to how film used to think about exposure. What that means is, you wanna push your histogram as far to the right as possible without blowing out important highlights, and that's the next slide here. Essentially, when I'm shooting, and we'll do a little example here with Tony. I'll just shoot some portraits of him, but this is for raw. So just to make sure you understand, this is for raw only. If you're shooting JPEG and you push that histogram all the way to the right, which is technically overexposing the image, you're just gonna get a bunch of overexposed images that you then have to correct. So in JPEG, forget about this. Just shoot at what is the right exposure for the image. But with raw, if you shoot to the right, you'll have a bunch of overexposed images that you bring into your workflow, but then you can pull the exposure down to the correct exposure, and you technically get less noise in the image. You technically get a better image in the end result, so that's kind of counterintuitive for a lot of people in terms of exposure. That's why this histogram is so important. Here's the histogram in the back of the camera like I showed you. This is how a lot of people use it. I typically like to shift it, as I was showing you, to this histogram that shows the red, green, and blue channels, because when I'm shooting a portrait, I don't want any of those channels blown out on the highlights side. Because if you do blow out some of the parts of the skin, when you pull it back in, there can be some color fringing that happens in those points. People don't like it when there's a green halo on their cheek. That's an old school thing. It doesn't happen that often anymore in digital photography. They've really figured out some stuff. Just some examples of histograms here, and we'll do an example. These are counterintuitive in that for this histogram, there are no pure highlights except for the sun, maybe. It's a little bit blown out, but I was trying to create somewhat of a silhouette on her. And a histogram just describes the image. There's some pure black in the image because there's some deep, dark shadows here. Here's the opposite. There are some pure black in the image, 'cause it's a black and white image, and I forced it to be pure black and pure white. But the background is white, so I forced the background to be pure white, and that's okay! I'm fully blowing out highlights, but I wanted those highlights to be blown out. So, I think if you haven't been looking at your histogram on the back of the camera, it's gonna be a little weird at first, but the more you shoot, the more it'll be like, "Okay, that makes sense now, why it looks like that." And you can play around by taking a variety of images, underexposing, and just keep increasing exposure 'til you're massively overexposing and see how the histogram changes, and that will give you a lot of experience with the histogram to understand what's going on. Here's one where it's in the middle. It's an overcast day. There's nothing that's pure white. There's nothing that's pure black in the image. The other thing with digital, when you're looking at the histogram, it really makes you look at what you're photographing. If I'm taking a picture of a Harley Davidson motorcycle, and it's full sunlight, there's gonna be some blown out stuff, because there's chrome on that bike, and that should be blown out. This is stuff we didn't think about with film because we just got the right exposure, and we didn't really worry about the relationship of the bright tones to the dark tones, necessarily, in the image. But now, with digital, we have to think about it a lot more. Here's the exposure workflow. Basically, whatever I'm taking a picture of, and I'm usually in manual or aperture priority. If the light's not changing too much, I'm usually in manual, and I'm gonna put myself in manual right now, actually. I just take a picture of what I'm taking a picture of. Let's have you come up, Tony. I'll just run through this real quick. I'll just have you stand right here somewhere. I think, 400 ISL. (camera shutter) Okay, that's a really long exposure. I didn't actually change any exposure settings, so I have to tweak that a little bit. So you can tell, I got a pure white image. That's not gonna work. I wasn't thinking clearly here. Alright, let me get up to a little higher shutter speed. (camera clicking) And now we're shooting wide open at 1. (camera shutter) See what that looks like. So, that's a decent exposure, but let me go to the other, the blues are a little bit blown out. I do have a illuminated blue background here, so I'm not too worried about the background. But I see that his forehead's blown out there. Whoops, touch screen on the Nikon. And I see that there's a little more room for the histogram to be pushed to the right, which is non-intuitive, because it looks like it's a fine exposure in the back of the camera, but this is not a calibrated LCD, so don't take this as gospel, especially if you're standing outside in full sunlight. The brightness of that has no relation to what you're actually looking at. Here, I'm gonna come in, and I'm gonna overexpose a little bit more. Let's go like 2/3 of a stop, see what we got there. So that histogram's pretty close to the edge. The blues are blown out, but that's the background, so I'm not worried. There is a little bit blown out on his face, so I'm gonna adjust again. (camera clicking) (camera shutter) See, what's happens here. So, just that little highlight on his face is a really big light right above him, so I'm not gonna worry about that. And with digital these days, the other thing with exposure is understanding the technology. So with these new cameras, like the Nikon D850, you can pull up the shadows slider in Lightroom and really bring out those deep, dark tones with almost no noise penalty. So for me, I'm really watching the highlights, and I let everything else fall where it may. It may or may not be the case for your camera, so you'll have to test this out. In the old days, that wouldn't work, you know. Four or five years ago, if you have a five or six year old camera, exposing for the highlights, letting everything else into shadow and then pulling it up in post may bring a lotta noise out. It just depends on your sensor and your camera, so I'll have to test that. For the D850, and the D810, and most of Nikon's current cameras, it works amazingly well. So I'm just going to basically go of off... There you go, moving your face around. Let me just shoot a bit, 'cause these will be the pictures we download, too. (camera shutter) Let me pull into higher frame rate mode here. (camera shutter) And then get in a little closer. (camera shutter) Alright, so, basically, once I get my histogram set, I forget about it. I don't look at the back of the camera, 'cause I'm looking through the camera, and I just shoot away. So if the situation changes, and the one thing I forgot to do here, let me do that now. Let me have you hold this, Tony. I forgot to set my custom white balance. So it's a little different on every camera. On the Nikon, you just put it on custom or preset white balance, and you hold down the button, and it starts blinking, and then, let's hold it up towards, yeah, there you go. And I fill the frame of the camera, (camera shutter) and it says good, so I have set a custom white balance. And that's taking an actual Kelvin reading off of this gray card, setting it in the camera, and so let me take one picture after that. (camera shutter) And that's changing my white balance. So now, I can use that picture as a reference to what is technically exact Kelvin temperature reading of the light we're using, which I'm guessing is probably daylight here in the studio. So, this is a great thing, and I usually give this to my assistant, because as you just saw, I forgot to do it. And I have them jam this up in front the person every time I start taking portraits, and that way I remember to do it. Or, if I don't use this, I use the ColorChecker Passport. If you're shooting Canon, or Sony possibly, it doesn't actually take a measurement reading in-camera. You have to take a picture of a gray card, and then you have to select that picture on the back of the camera, and then it sets a custom white balance reading off of the picture you took of the gray card. I found that to be a little accurate than the camera measuring it in-camera, but it doesn't matter. It gives you a reference point or a base point. I will say for the Hasselblad, the colors are tuned for skin tones better than any other camera I've ever used, bar none. And so, doing a gray card with that camera, I mean the skin tones are just like so good straight outta the camera that you barely have to touch 'em. Just depends on the camera and how it's tuned. Thank you, Tony. Any questions on that histogram...
Let me take a peek, particularly on histogram. So, this is always a question, Michael, that we get quite a lot, about when you're having your card on assignment, gray card, white card, for a custom balance, what do you prefer and why?
Depends on your camera. I have found my early Nikons, I would use the white side of this. Like I'm talking very early Nikons, back to the D70, it was better on the white than it was on gray. Every Nikon after that, It's been better on the gray. Most Canon shooters that I know never do this, because their auto white balance is pleasing to them out of camera, I don't know. I'm not a Canon shooter, you know. Hasselblad people or any medium format camera, anybody in the studio, you almost always see, probably not this, but you see the ColorChecker Passport. And, actually, I don't have it up here with me, but we saw the slide. Let me go back to that slide, because the thing with the ColorChecker Passport... Sorry, I'm zoomin' back here. Where was that? There we go. The thing with this ColorChecker Passport is it not only has white to black and all these colors, it has all of these that are slightly color-toned, so that you can warm up your image, or cool down your image. And you get into Photoshop, these three squares right here, red, green, blue, you can actually dial in the color super accurately using your color droppers on each one of those to make sure they are pure red, green, and blue. And then, you'll have, technically, a perfect, no color cast on your image, a neutral image, at least. So, that's a much more accurate tool than this, just a gray card. This is just an 18% gray card, but it really helps. It really save you a lot of time in the post-processing. You may not leave the white balance right there, but at least you know it's an accurate starting point. Technically, this is way more accurate than film ever was, 'cause every film had its own rendition of color that was different, and you chose the film based on whichever color rendering you wanted.
So, each one of your cameras is specifically calibrated?
Yeah, if I'm shooting with two cameras, I'll do one for each, but typically I'm only shooting with one camera in that scenario. And I don't do this, necessarily, for every, if I'm shooting action, adventure sports, I'm not necessarily doing this then, maybe I will. It's usually with portraiture, where skin tones can get really persnickety, you know. And the interesting thing with that is that most of us have much more red. Most of us that are pasty, white people, have much more red in our face than we like to think we do. 'Cause we've seen for years, film, and movies, give us a certain look through skin tone, and so we have this pre-visualized idea of what skin tone looks like, when in reality, it might be a little different. Just depends on your complexion, and I'm certainly very pasty. Grab the mic from there, Tony.
Yeah, can you talk about the relationship between your exposure meter and your histogram, in that when I shoot, and I'm shooting fast and relying on my exposure meter, and maybe another question that, is you could bring in the zone system. So if I am shooting snow, I'm gonna lose that upper of part of the histogram.
It's tricky. I mean if you're shooting fast, let's take the first part of that question. Say I'm shooting sports, or I'm shooting surfing, and I'm bouncing around on a jet ski, or I'm swimming, and I'm not gonna be dialing in the histogram for every single shot. I basically get it to a nice medium, middle area, just because that's the reality of that situation, and shoot away, protecting the highlights. Maybe I'm in an automatic mode, and I dial in the exposure compensation, negative .3, negative .7, and sometimes if the sun's in the frame, it's gonna blow out, that's totally fine, but I just wanna protect some of the highlights. If I'm shooting on snow, maybe I want all the detail in the snow, so I can adjust the histogram there. The point is you have the choice. Snow should be white, but it shouldn't have no detail, necessarily, everywhere. It might be pure white in some parts of the snow. It just depends on the situation. And if you protect the highlights a little bit, you can always adjust that in post, to blow out those highlights, just like the black and white image wasn't pure white on the background, that I showed you, but I forced it to pure white in the post, so it depends on the situation you're working with, and how much time you have to do that, you know. On a lot of my shoots, I'm working with an athlete. We have time; it's not a rushed thing. It's not like I'm shooting an event. That's pretty rare for me. If I was shooting an event, I don't have time to like, "Stop, hey, hold that pose. Let's see my histogram." You have to tweak the workflow depending on what you're doing, but just be aware of that. Basically, every time I'm looking at the back of the camera, I'm probably not looking at the image. I'm looking at the histogram, or I'm double-tapping the image to zoom in to see if it's sharp. That might be the only way I'm really looking at the image. Histograms seem like a very complex thing, but the more you use 'em, the easier it'll be to read 'em. I'm not gonna get into, we could go way deep on histograms, 'cause technically that histogram is not the histogram for your raw image. It's the histogram for a JPEG, so that creates other problems, but yeah. I'll definitely touch on that. Ask me some questions about that when we start working in Lightroom, 'cause there's a few caveats that are pretty crazy that the camera manufacturers could really improve.