Using the Histogram for Better Exposure: Exploring Photography with Mark Wallace

Hi everybody welcome to another episode of Exploring Photography right here on AdoramaTV, brought to you by Adorama. It’s the camera store that has everything for photographers like you and me. In this episode I want to talk to you about the histogram and how you can use it, to make sure you’re getting the correct exposure and to avoid dynamic range issues. In other words, how does the histogram help us in real life shooting from day to day? Well first, let’s talk about what the histogram is. When we take a picture our camera is capturing not only color but tonal values. In other words, absolute black, to middle gray, to absolute white and everything in between. What the histogram does is, it plots all those values on a scale so we can see how many black pixels or dots do we have in our picture, how many gray pixels, how many white pixels? We can use that, to see if our exposure is correct, or if we have issues with things either too bright or too dark. In other words, “dynamic range”. Now, to help understand this let’s think about a classroom. So we’ve got a bunch of students sitting in desks. Some of the students are pretty smart. They’re going to get A grades. Some of them are going to get B’s, some C’s and then we’re going to have some kids that aren’t so disciplined. They’re going to get D’s and some will fail the class, they’re going to get F’s. We can take those grades, those values, and we can plot them on a scale and show the distribution of those values. So the A’s will go here, the B’s will go here, C’s, D’s and our F’s. The important thing to understand is, it doesn’t really matter where those students are sitting in the classroom. Doesn’t matter if the A students are on the left and the F students are on the right, it doesn’t work that way. It’s just showing the distribution of our values. The A’s go on the left column the B’s next to it, all the way over to the F. In the same way when we take a picture, it’s not showing us what the different values from left to right in our scene, it’s just showing us on the left-hand side of that histogram that’s how many black pixels we have in our camera and how many middle grays and how many whites. To illustrate this point, I found this wall here. There’s a black portion and a white portion but watch what happens if I take a picture of just this white door. Watch what happens. So I’ll take a picture here and now I’m going to take a picture of this black section right here. I’ll do that. Okay Now if we look at these two images side by side, you’ll see that they are both gray. Now the reason for that is the camera’s through the lens metering, is trying to average all these tones out to get middle gray but if it’s white? It’s going to do something that’s wrong, it’s going to make it gray and if it’s totally black it’s also going to be wrong, it’s going to overexpose and make it gray instead of black. Watch what happens if I take these pictures together. So I’ll put the black door and the white wall together and now you can see that we have both black and white. So how do we know in a real-life situation if our camera was getting something wrong? Well, that’s where the histogram comes in. So if I take a look at my histogram for the black wall, you can see clearly that it’s right in the center. So my histogram is telling me this is overexposed. If I look at the white wall you can see again that my histogram is showing me all the values are right in the center saying, hey this is underexposed. So using that histogram I can see if my camera is getting my exposure correct. Now, we’re not going to ever be shooting, I hope, just a black wall or a white door. We need to look and see how this is going to work in a real life situation. So let’s do that next. Here are some tiles that have caught my attention here on this busy street and what I want to do is take a picture of this. I also want to get some of this pipe here because it’s got some texture and I really like that. Now because these are almost white, I think my exposure might be off, just like that white door. So I’m going to frame this up just a little bit here, make sure I’m all in focus. I’m using Aperture Priority mode, and I’m shooting and when I look at my histogram here I can see that it is underexposed. This on the histogram should show up in the highlight area but it’s showing up right in the middle as middle gray, so just like that white door, this is underexposed. So what I’m going to do is, I’m going to use Exposure Compensation. I’m going to adjust my exposure by about a stop and then I’m going to shoot again. This is going to slow down my shutter speed. Now take a look. Now that is showing up in the correct area of my histogram, right in the highlight area toward the right side of the histogram and that is the correct exposure. So the histogram is going to let me know if this is correct or not without having to go into post-production to make adjustments. Our histogram can help us understand if we have any exposure issues, specifically dynamic range issues. Now, dynamic range is our camera’s ability to capture the darkest of darks, to the brightest of brights and how much of that we can capture is our cameras dynamic range. If you have something that’s a little bit too bright or a little bit too dark it will fall out of the exposure. In other words, it’s going to have no detail in the brights or no detail in the darks. We don’t want that and so our histogram can tell us if we have an issue. So behind me I have sort of a bland scene but it’s perfect for illustrating this. I’m going to turn around here, I’ve got this little patch of sky up there. So I’m going to take a picture of this little grove of trees here. When I do that I can look at my histogram and my histogram is telling me that I have an issue over on the right-hand side of my histogram, there’s a spike. We have our whites that are climbing the wall. In other words, there’s a spike to the right and that’s an indication that something is overexposed. So if I zoom in, I can see that clearly the sky is way overexposed. My histogram is telling me I’ve got an issue with that part of the sky so I can either shoot a HDR image or shoot at a different time of day, which is probably the best solution, or just shoot from a different angle, or shoot something else. Right now my histogram is saying if you shoot that, right now, I’ve got an issue. Our histogram can also make sure that we have a proper exposure and tell us if we have any issues. Now check this out, so Salim here who’s been doing some B-roll and camera operating, so he’s been running the video camera for me, he has volunteered to be the model today. So I’m going to take a picture of him. Behind us we have sort of, a dark background we have some overcast light right here, really nice soft light so I want to see if this is going to give us a proper exposure. So I’m shooting at f/1.4, ISO 200 at 1/750th sec. Salim, look right into the lens here. Take one more shot, and then what I’m looking at, on the histogram, is to see if I have any issues. But my histogram shows me that I have room to the left and room to the right and all the values in between are falling in the middle of that histogram and that means, that I have nothing in this scene that’s absolute black, nothing that’s absolute white. That means in post-production if I want to tweak this to make it a little bit more contrasted, I’ve got room to grow. This is a good exposure. Nothing’s climbing the wall to the right or the left. I can just look and see that everything is good. There you have it, the histogram can help you when you’re out shooting to make sure you get a proper exposure and to make sure you avoid dynamic range issues. If you want to know more about the histogram specifically for post-production check out the Adorama Learning Center, there’s all kinds of things, in fact, one of my favorites is my video about using the zone system for black and white photography, make sure you check that out. There’s something else I need to tell you, I’m starting to write articles every other week for the Adorama Learning Center so check them out. It’s absolutely free and also don’t forget to subscribe to AdoramaTV, that way you don’t miss a single thing. Thank you so much for joining me and I will see you again next time.

14 Replies to “Using the Histogram for Better Exposure: Exploring Photography with Mark Wallace”

  1. If you are photographing a white carnation against blurred out dark greenery would it be better to expose the right hand lump showing the flower as far to the right as you can go to get white detail? Then would the dark lump on the left probably not worth being concerned about because it is serving simply as contrasting negative space? Is that logic correct?

  2. A great explanation of this subject. I have seen too many videos on this subject that do not include examples of histograms in various situations.
    Thank you.

  3. Great explanation Mark. Thank F**k theres someone sensible and coherent on YouTube

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