Understanding Histograms Part 2
Create a photo that is a high contrast and we're gonna need that power cable on that light. I need a pocket wizard on the other end of this. I'll use this one I guess. I'll use this one. This light meter by the way has a pocket wizard built in. It's broken and so, we added one, manually. So that's why this is hanging on. Normally this would not be here, so Sekonic is probably cringing right now going "Why didn't you just call us?" But so I'm triggering that light with this pocket wizard through this cable. But normally I would just do it manually. So. Perfect, see if I can change my scale here. Good, good, good, memory clear. Alright. So here's what we're gonna do. If you could hold this for just a second. We're gonna create a very high contrast light-- Oh I need to grid. The grid I need like a ten degree grid if you have one. Yeah we're gonna create a very high contrast image. And we're gonna try and look and see, and we're gonna have you stand much much closer to that. You can actual...
ly stand on it, stand right on it. Keep comin' back, keep comin' back. Good. Okay. We're gonna create a very high contrast image on purpose. And so this is, again one of those images that we're creating not to create a great image of Lex, but to create something that we can manage for science. This is for science. Fun for science. Alright, so what we're gonna do here is we're gonna create a light on Lex's face very close. There we go, we've got some shadows. Alright, now, what I'm gonna do is I'm going to take this and this meter has a feature, I can take this and twist this nob right here. And what that does is it says, when it's on this mode, it's using the lumisphere to gather values and so it's Incident Metering. When I twist this it's now in Reflected Metering mode and I'm looking through this little thing and it looks just like a gun sight and so I can see through that. And there's a tiny little dot inside there and it's very specific so I can look through here sort of like a telescope or a microscope, whichever one you want to think of this as. And I'm gonna shoot this. (electronic beep) There we go, and I can meter and it will give me a reflected value at that point. And it's expecting that reflected value to be middle gray just like through the lens metering. But the difference is I have a little scale at the bottom of this, and I'm not sure this will ever show up, but there's a tiny little scale here that's got a zero and it goes all the way down to minus, let's see, minus seven and plus seven. Those are stops. And I've calibrated this to my camera. So as I take readings, what I'm gonna do is I'm gonna take a reading on this side and there's memory button on that side, and I'll stick it on the scale. And I'll take another reading and put it in memory and it's gonna start showing me where those things fall on the scale above or below zero, in relationship to each other. And then it will tell me if all of those values fall outside of the dynamic range of my camera. So what I'm not doing is metering to see what the exposure value is yet, I will. I'm metering to see if this can actually be captured by my camera or not, that's what I want to know. And so what I'm gonna look at here is, I'm gonna look at values right here that are really really dark. I'm gonna look at values here that are really really bright and in between and I'll plot these on a scale and I'll see, do we have, like, is her forehead too bright in comparison to her shirt? And if it is then I need to do something. I need to maybe put some kind of diffusion in here or something that takes that value down. Or is this so dark that it's not gonna show up, do I need to add a little bit of fill light? So using a tool like this on a very complicated setup, you can actually see if this is going to work, scientifically before you ever take a picture. And it's pretty spectacular, and this is used a lot in scenic photography when you're trying to plot out exactly what it is. And the other thing we can do is, we can choose what is middle gray. We're not gonna let our meter tell us, we're gonna tell our meter what we think middle gray should be. So I'm gonna do this really quickly, and so what I'm doing here is I'm gonna start with the very darkest tone I want in my scene. So I'm gonna actually get right here, trigger that, and I'm going to put that in memory and then what I'm going to do is I'm going to go to the brightest point, trigger that, put that in memory. And we see, right off the bat, that I have a problem. It tells me right off the bat. It's got this little 'O' saying the difference between this and this, no way. Not gonna happen. And so I know, this is gonna be out of the question. So what I'll do is I'm gonna clear my memory out everything's cleared out. And I'm gonna just see from here to here how we're doin'. So we already know this is not gonna work, right? Sort of cool. So I'm now metering on the collar, put that in memory metering on her forehead, putting that in memory, and right now it's saying, "You're at the edge." And then what I'll do, is I'm going to average that. And it's telling me, on this scale, the F10 is middle gray between those two. When it averages the brightest, and the darkest, it's saying middle gray should get you to that point. And on this scale here, we'll look and see if you can see it at home. You can see how those two points are at the edges of our limit. So we'll take a picture at F10 really fast, and we'll see how it goes. And the other thing I just realized is I calibrated this to a different camera. I calibrated it to my 1DS Mark II which is a much older camera and so it's got a smaller dynamic range then the camera that I'm using so this probably would have a little bit more leeway then what I'm using now. We'll take a picture though. F10 is what we're gonna use, and I'll just take a shot. Thanks John. And we'll see how it goes. Now the other thing you could do, we don't have the time to just really go into that but we could have done many many readings along the way and that is something that I do if I have a scene where I have a bunch of different pockets of light and I'm trying to sculpt light in different places. I'll usually go through and meter all of those different things to try and see where I need to add or subtract light, and change that light. This is something that is not a common thing to do by the way for most photographers. But once you've done it a few times, it is really fun 'cause you can sort of see what's gonna happen. Okay, so we're gonna take this photo, at F with my focus actually turned on. And we have an issue with my lens. Okay. And I think my tethering is, let's see if my tethering is messed up here.
Is it saying busy?
Yeah, so it's saying busy, so it's saying that my tethered capture, Start Tethered Capture. There we go. Alright, there we go. Now let's try that. Yeah so when this camera auto shut-off a few minutes ago, and so when it did it turned the tethering off, and then when I turned the camera back on and it probably tried to connect to Adobe photo, whatever, Lightroom, or something. And so that did that. Alright so we're ready to go John? Okay. F10 and we're gonna try to take two photos here. Okay, Lex we are finished with that, thank you. Alright I want to show you a couple things here. Perfect. Yeah so we'll show the first one here. So we said on the first photo here, when we metered it remember I metered right here and I said, the meter said "No way, it's not gonna happen."? Okay, Lightroom says the same thing. It says there's no detail there, so we know without taking a photo if it's gonna work or not. And its pretty awesome that we can do that kind of stuff. So, we're done with that demo, and I'm curious what kind of questions that we have around that. I'm gonna turn this off as we're going. But that's a technique that is based on something called the Zone System where you look at a scene in your brain or in real life, you convert that to a 12 stop gray-scale image which we don't do anymore 'cause our cameras don't do 12 stops. But you meter and say where do I want the black to be, where do I want the middle gray to be, where do I want the white to be? And you map those values to a middle gray and you set your exposure on that. And you do it with Reflective Metering just like that. And you have to sort of adjust the light to fit within that scale. Our scale now is not 12 stops it's 5 stops. You went to Brooks is that right? They taught that at Brooks I'm sure. It's something that, that you have to know when you're working with film. And the same is true of printing and developing and all kinds of stuff. Most people don't know about the Zone System anymore, because you don't need it as much, 'cause it's all it's a different system. Okay, I'm curious if we have questions about this stuff, do you have any questions? Yes sir.
Do you ever use the slider that's on the histogram itself?
Yeah I do! And in fact that's a great point. What you can do is, it's the same thing. So we'll use a different image here. We'll use this picture of Lex up on the rooftop. And we're in the Develop Module. So what you can do here is instead of going to the Shadows and adjusting those with this slider here, see how much more detail we can bring out of her coat doing that? What you can do is you can just go up here and adjust there. It's the exact same thing. You're just doing it on the histogram itself. So, sometimes I do that, I always forget that it's there. So, yeah. Same thing though. Alright, any other questions about that?
Mark and this is a little bit off topic, but we've been getting this question for the last few days. Peter in Cheshire wants to know, says "Great three days Mark. Thank you." And says "What's the best color for photo studio walls?"
I prefer white. I prefer white because then you have the flexibility to bounce off those walls. And with white walls you can always put curtains or subtraction panels in front of those to stop those reflections if you don't need them. But you have a lot of flexibility with white walls. I know a lot of photographers prefer gray walls or dark gray walls but I think for the most part most of the studios I've ever worked in have white walls. John you've worked in a ton of studios, have you seen--
White or some of the still life studios I've worked in have just so many cabinets and junk all around that I don't even know what color the walls were.
Yeah, I have a friend, Rick Gail in Phoenix, he's a phenomenal food photographer, and he's the same way. He's got just this amazing assortment of highly organized tools and they're in all these cabinets and stuff. And so he doesn't even have walls he just has all these really awesome, and it's not like cabinets of things thrown in there. They're all like compartmentalized and perfectly labeled, it's pretty amazing.
The inverse where if the lights are in that close you know if you're lighting in really close, then it's not as big a problem unless you're going to bigger sets.
Yes absolutely. Just give you a lot of flexibility.
Alright, a clarification question from Steve who said, you were saying earlier that you had used the histogram to determine if the exposure was correct. Can you explain exactly what you're looking for?
Yep. Absolutely! Let's just go look through a couple of photos and we can, I'm gonna turn off the histogram over here. Wonder if I can actually, yep. Can do that. Alright let's take a look at a couple of photos. Let's take a look at this photo here. This is over-exposed. We know that. But what we're gonna do is we're gonna reverse engineer this histogram. So let's pretend that this was a correct exposure, we wanted it to look like this. If we looked at our histogram, let's say this is our histogram. What we should have here, there is this right here, is light gray, correct? Is there any black in this image anywhere? No. Not at all. So we should start to see some values around the middle gray area and we should see a lot of values over here in the white area, something similar to this. It's not gonna look like this. But we should see very few values down here if that was a correct, if that's what we wanted, this is what we should see. And if the histogram didn't look something like this we would know that something went wrong. So now I'm gonna revel the histogram, and see what it looks like. Look at that. So we have a lot of these gray values but a ton of white values. Let's say that we wanted this to be exposed correctly. We look at her shirt, it's black. Is there anything black in this histogram? No. So we know that it's incorrectly exposed. So if we scope it in here start bringing that down. It'll never look right 'cause the values that we needed have been lost 'cause it was so overexposed. Let's look at another image and then I'm going to take a test of the students in here. I'll try to make it an easier one. Okay. This image here. Alright, what should this histogram look like? What should it look like? How much black should be in this histogram? Yes?
Like a 'U'?
A 'U' shape.
A 'U' shape? I like where you're going. I think sort of, so down here we should have, are there any absolute blacks in this image? Yeah, so. In this area, we have I think dark shadows. I don't think these are absolute black but I'm gonna go with you and say we should have something in this area here. We should have something down there. The whites, do we have lots of white here? Ah, you're gonna be fooled. This is gray. We'll see its gray. So I'm guessing we should have a lot of something in this area, right, something there. And then skin tones are usually around the mid tones. So I'm thinkin' we should have a little bit of something here. So I think we're gonna have a little, a little, and then a little spike, something like that. So let's see what we have. Okay this was a little bit, I over-estimated that. But we have this sort of similar shape, like that. So it's not quite a 'U' but its a (rising tone) 'U'. So that's what we're looking for is, does the histogram represent what the image should look like? And so let's do one more. And we'll go to, say, we were shooting out on the rooftop. Okay, this image here. So this shot here, our histogram, when I look on the back of the camera here, you can see that we don't have any absolute whites, we don't have any absolute blacks but we have values in between. Alright, that's what we have. So that may or may not be a good histogram for this image. 'Cause this image has a lot going on in it, right? It's got all kinds of tones all over the place. But what I'm looking for when I'm shooting on location is, are any of the blacks clipped, or any of the whites clipped, and does it fall within the range that I should expect? In other words, if this histogram, looked like this, and everything was bunched over to the left-hand side, we would know without ever seeing the picture that there was an issue because we have, you know clean bright teeth and we have a nice bright sky, and we have some bright tones, but on the histogram none of those are represented. So we would know, "Oh, we're underexposed." Or if we had the opposite up here, I'm gonna turn off this, so we can see. We know that we have a black coat and we have some dark buildings and stuff. We should have some dark values on this histogram, and with this exposure we don't have any of those. So you can sort of see if things are to the right or to the left to the extreme that we would have some issues. So that's how we would use the histogram to sort of figure that out. Okay? We're good? We have one more question.
So in this, this is a rookie question, sorry. But I know that this monitor wasn't calibrated so when you're actually looking at the image and the histogram how do you know how close your monitor is to true colors so that you're not adjusting for the image you're seeing versus what the image actually is?
You should calibrate your monitor. So John, in there, there's a color monkey. I think. Have you ever seen a color monkey? If you can grab that for me, I show you how you fix that. So, you need something to calibrate your monitor, and this is what I use. This is called a color monkey and what it does is it's got a USB cable and this little thing here helps to support it. But it's got several sensors, so it has one here. You can rotate this sensor this way, and it can go here, so it actually, there it goes, so you can have a sensor here. It goes here so it comes out that way. And forward, and up. So what this will do in the up position, this is gonna monitor ambient light. Because guess what? The ambient light is going to impact what you see on your screen. So if you're in a dark room your screen is gonna appear brighter. If you're in a bright room your screen is gonna appear darker. So you should take into account the ambient light and how your screen looks. And also the color temperature of the stuff floating around is gonna impact that as well. So with a good calibration tool it should always have something that monitors the ambient light. And with this one you can actually leave it plugged in and as the ambient light changes it senses that and changes the monitor to respond. So it's pretty nice. You can forward, this is for calibrating projectors. So you wanna calibrate a projector to see. You can go forward one more and what this guy does, is it allows you to, let's say you're doing... We're working with this, this thingy right here. And they want us to make sure that our graphic design has this exact red in it. Well you can take this and put it on that spot and then go like this, and it will sample that color, just like if you go to home depot and say "I want this red paint." That does that. So you can actually sample colors and that's for building color palettes. And then one more click and it puts it down through this hole and what that does is you can put that on your actual, physical screen like that. And it goes through a test and it puts a bunch of different black and gray and middle gray and red and blue and green and all these different colors and it says "Hey I'm expecting red, what are you giving me? "Oh that's not red it needs to be adjusted this much. "And I'm expecting black, what are you giving me? "Oh that's not black that's a brighter gray." And so that will actually create a color profile for the screen and apply it and then your screen will have color, will be color corrected. The thing, though, about doing that, is nobody else is going to have a color corrected screen. And when you color correct your screen, make it accurate, it will look dim and desaturated in a lot of times. Because it's gonna match what the real colors are and it's gonna match what you can print. So what will happen is you'll create images for the web and when you go to throw those to the web everybody else is gonna look at them and go "These look weird." Because you did it on a monitor that had a totally different profile than them. So what I do, is I use, it's called the S.R.G.B profile most of the time when I'm editing for the web 'cause that's what everybody else uses. And then when I'm editing for an Art Department or for a commercial client, what I'll do is I'll use my calibrated screen. So again we're, we need a color management theory class. Alright, what other questions do we have?
So we have a couple folks asking about the calibration between your light meter and your camera. Is there a process to that?
There is. John somewhere in that stack of, those, yeah the big color checker and the black gray, there is a calibration target somewhere. Maybe you could find that. So the way this works, and you can't do this with all light meters, exactly like I'm about to describe it. But on a light meter like this, what you would do is, it doesn't have a USB port where you can connect it to a computer to do calibration. But what you can do is you can meter the light where there's a gray card, take a photo. Take that photo, put it into Lightroom or Adobe Camera Raw or whatever. I'm going to pick, there it is. I think that's it. If you could open that. I think that's the thing. But you can take that and you can say "Alright this should be middle gray, is it middle gray?" And if it's not it's going be over or underexposed by a certain bit. And if it's overexposed you take this and you do the adjustment. You say "You know what let's adjust by negative 1/10th of a stop or 2/10ths of a stop." Whatever that is. And then you'll take another reading, put that in the computer, check to see if that's actually middle gray and you just sort of dial it in manually until you get to the right place. With the newer meters what you get is this. And this target by the way is, I think a couple hundred dollars for this thing. It's crazy expensive. I might be wrong. But what it has, is these are highly calibrated chips of different luminosities and specific grays. And you can't even touch them because the oil on your hand is going to affect that. So you get one of these guys and you have to put it in a place where you have an even illumination. And then you take a series of photos and that series of photos, I believe it's, you have to go through I think 10 stops or six stops. So you would underexpose by three stops, by two stops, by one stop, an accurate exposure, over expose, over expose, over expose. So you're going through a range of exposures. And it takes some time 'cause it has to make sure it's done correctly. Then you take all of those photos, I think it's a 12 photo process, of this, and the software that comes with the newer Sekonic meters take that and then it says, "Okay, these are all the different values we got at these different settings." And that would be in, just with your camera set to manual mode and just shooting through what it thinks is correct in under and overexposing. So you put that into this software and what it does is it calculates how close the meter reading was to what actually happened in the camera. And because there's such a large data set, it's able to really accurately calibrate your camera, or calibrate your meter. And what the meter is calibrated to, actually, is not just the camera, it's the lens and the camera. Because different lenses behave differently with different types of light because of all of those lens elements that we talked about. And so some lenses will let in just a little bit more light than another lens. And so if you really want to be accurate, you'll have to profile every camera and lens combination you have. And so I've got, on a different laptop actually in the studio, I've got all these targets. And so I know with my 1DS Mark II 70 to 200 millimeter lens, I actually load that profile into my meter and when I'm metering it's still highly accurate. But as soon as I change to a 24 to 70 lens I change the calibration for that set. If I bring my 5D Mark III on then I go to that calibrated meter. If I get my Nikon D3X then I, so you see how that goes. It's not something you need to do, it's not something everybody needs to do. So it's just it's one of those thing that you can do if you want to be highly accurate.
Thank goodness for that. Everybody over here was like, their mouths went open. Like "I have to do what?"
Yeah, it's, and it takes about an hour to do each camera lens combination, maybe little bit less than that. So it's not a process that you just do, and you're done. And, here's the nice thing, cameras, over time, and meters, over time, they sway a little bit so you have to keep calibrating them. Yeah. So much fun.
I have a question from Tufftootle. "So how do you adjust all of these same settings "when you haven't used a gray card at all. "Are you just guessing by using the histogram?"
You need a gray card. Spend the six bucks.
You need a gray card.
Yeah, you have to have some, that'd be like how can you accurately know that your chicken is roasted properly without a thermometer? Well you could see if you get sick, but no you need a thermometer, right? You need some kind of way to see that. When you take a photo using different colors, those colors don't always translate equally to a black and white mix. And so what we have is, we have some objects of different colors and we're gonna take a photo of that. And we're gonna show you. And it looks like we have a locked wheel or something. So John's gonna bring that out. And then, I'm gonna trade you. I'm just gonna put this right over here. Okay. Alright. And if we can get that little softbox that'd be great. Alright, so my shoes untied again we're just gonna go with it, alright? So we have some things of different color here. We have greenish. Green, yellow, red, and blue. And what we're gonna do is take a picture of that. Here you go John. Thank you. I'll say it again, everybody needs a Cornicello. You know it sort of sounds like a Thanksgiving thing. Doesn't it? Cornicello's on the table. Everybody's thankful. Thank you for laughing at that. (audience laughs) You can tell everybody's getting tired, myself included. Alright, we're just gonna sort of take a photo of green tea and yellow mustard, and tomato ketchup. Tomato ketchup. Alright. Lacy did this right? Who did this? It was awesome. Did Tessa do this? These are people that behind the scenes are doing all the kinds of stuff that nobody gets to see, so. Like two hours ago I'm like "I need an assortment of "different colored things." 5.6. Okay. Just gonna take a picture of these things at 5.6. There we go, got it. It's all good. Thank you John. Alright, let's take one last look in Lightroom at something that I think is pretty fun. And that is, what happens when we convert this to black and white? Alright we have our stuff. We have that. When we convert this to black and white, notice that green and yellow are the same tone of gray, right? They look the same. So if you had something like an outfit that was green and yellow of different patterns and you converted that to black and white, it would all, you wouldn't be able to tell anymore what was green and what was gray. And look at the red. It looks very very dark. And yellow over here, also just bright gray. And so it would be nice if there was a way that we could adjust the luminosity or the tonal values of different colors independent of each other. And the truth is, you can. In fact, on Lightroom, when you go into the preferences of Lightroom, one of the things that it's going to ask you, let's see if I can find this, okay. When, it's, it's right here. Should it auto apply a mix on first converting to black and white? In other words it's saying "We had to figure out "how to convert green to a certain shade of gray "and red to a certain shade of gray and all these things. "So which shade of grays do we use? "Should we just do it automatically or "would you like to choose?" And so I leave the auto on, but this can really be impacted when you're working in portraits or more specifically in a scene. It's gonna have an impact on the colors that you choose if you're shooting for black and white. So it's very important to understand this. So what we can do here is, is there is a Black & White Mix when you're mixing. And this is not only in Lightroom but it's also in Adobe Camera Raw and a lot of Raw Converters. So when you're converting something don't just say "Make it black and white." You want to say "Make it black and white, "in an intelligent way." And so what we're gonna do here is were gonna start looking at some things. So check this out. If I take this slider here, this red, and I change it, look at that I can change how the red is converted. I can make red look really black, or I can make red look very bright. If I wanted to take that green and make it a different color than the yellow, I can do that. If I want to make yellow a little bit brighter, I can do that. And so the point here is, as we're going through and converting things it's important to understand that all colors are not created equal when it comes to that conversion. So let's go to a practical example of this. Let's say that we have this shot here of Lex. And we want to take that and convert it to black and white. Okay, looks great. Now we want to do here is we want to do some manipulations to this photo to bring out different areas of the image. So we could go in here and we could working with the blacks and the shadows and all that kind of stuff that I just showed you. The other thing that we can do is we can sort of go in here and start working with the Black & White Mix. And so I know based on experience that people's skin tend to have lots of reds and oranges and yellows in them. And so if I go in here to orange, look at that. Ew she looks very, she's been at the beach too much. (audience laughs) Right? So we can start working with different areas of the photo. And if you're not sure, like, what is the color of this? What you can do is there's this little guy right here, it's this little thing you can click. And when you do you can go over to the image and you can click and drag up or down. It turns out that that is in the blue range. There's some blues in there. But notice behind her head there's something that's blue as well. And so it depends you might wanna say "Ahh, that's sort of "ugly back there in the background we want "to mix those so they're not so bad." Or we could say "You know what, we need to "bring more detail out in the coat." But in the coat there's not a lot of color. We know that 'cause it was a black coat. So in the coat we might go up and say "Oh we're just gonna go into the shadows here and we'll "adjust the shadows and leave everything else alone." So notice when I'm adjusting the shadows it leaves the background alone. And so when you're, we're doing those tonality adjustments in black and white, I love to work in black and white, you can intentionally shoot things with certain colors so that in post-production you can adjust those different things independent of each other. One of the things that drives me bonkers is when I forget to tell a makeup artist that I'm shooting in black and white and they use a lipstick color that's problematic. And so for example let's go in here. We have really bright red lipstick today. That's really cool. So if we convert this to black and white, okay? I sort of like when we shoot with bright red lipstick for conversions to black and white because it makes the lips go immediately to a really nice dark. But if I go in here and start working with the reds, notice that her cheeks and those highlights are also being affected. So you have to be really careful with those types of things. The other thing is if we had, if we could see a little bit more of Lex's dress here, we convert that to black and white, now what's happening when we adjust the reds it's adjusting her shirt as well. And so sometimes I'll have a makeup artist who I don't communicate with and they'll use some kind of horrid color like a green or something and when I'm trying to change that, it happens to match the outfit that they're wearing 'cause that's sort of how they work. They're like "Oh they're wearing this color of outfit. "We're gonna do this color of lipstick." And I forget to tell them, "Please don't do that. "Put the wrong color of lipstick on because I'm gonna be adjusting the shirt independent and I don't wanna have to be worrying about lips at the same time." And so it's just something to remember if you're gonna be shooting for black and white that there are some considerations for that.