Understanding Dynamic Range
Dynamic range now to illustrate this we're going to use some colored candies so we'll go and bring in the, uh, ambient light up now to talk about this don't bring these all the way over here all right? I'm about to make a big mess you let it all right so dynamic range there is uh this uh, definition here and it's on is going to read it is the difference between the smallest and the largest amount of grey that a system can represent and it's also the difference between the lightest highlight and the d max maximum density in this system well, right all right, that doesn't make much sense to me but dynamic range um wanna put it in layman's terms okay, because that is technically correct but it doesn't really help me out because I'm not a scientist. I'm bad at science and bad at math so I need a better way to understand it so let's pretend for a second amy you guys like music go to the symphony you love that. Okay, let's pretend all right, ellen I'm gonna pretend that you are rach come on ...
enough you love rock monitor. Okay, go with me on this you love rockman enough, okay, so rachmaninoff third right rach three dotted added so you go and you see a full symphony orchestra and you hear this amazing music right? You're like orchestra seats you're there it's I don't know someone the kennedy center let's say new york city and you hear rock man enough for the first time in your blown away which you will be every listener rachmaninoff you'll love it on dh you're like wow rachmaninoff I need mohr rock mon enough in my life and so uh you go home and unfortunately you're just not a very educated person as faras your audio gear so you go to a truck stop and you buy one of those white plastic cruddy cassette tape players with one speaker in a cassette of rachmaninoff right? And you throw it in and you play rachmaninoff and what you get is this really tinny nasty? You kind of sound right? So what's happening is that plastic cruddy truck stop cassette tape player is not producing the audio levels close to what we here in real life so the dynamic range of that is very restricted we don't hear the lows we don't hear the highs the woodwinds don't sound right you know the cello is the lows, they're the resin on the street all this lost right? We don't hear any of that stuff and so what you do is you say I don't know I cannot have this I need rock monnitoff so ugo you educate yourself you come home, you get vinyl you get a turntable and you get handpicked would speakers and you have your room optimized and now when you play the vinyl of rachmaninoff er that feels your soul with music that's awesome and what happens is now what you're experiencing your home very closely replicates what you hear in real life the dynamic range of those speakers are very similar to what you hear in real life so what we're trying to do a dynamic range the practical application is we see things with their eyes that are cameras cannot capture we see sunsets, we see our friends on the beach all at the same time we see the campfire, we see the s'mores and we take a picture always see your silhouettes in sunset or friends and blasted out skye because the dynamic range of our cameras can't approximate reality and what we have to do is we have to find a way to take reality and smush it into a format that our cameras can capture that's really all we care about when we're talking about dynamic range so let's figure out how to do that so I got these old slides here this first lied let's pretend that this represents from left to right all the different levels that are ice concedes so we can see about you know I know that the scientists out there going to debate with me instantly on chat but about twenty four stops of light okay, now are our eyes our special we have a brain and ari says that go up and down and comes and rising like stuff but we can see about twenty four stops of light we can see all that in real life now back in the old days when we had actual film emulsion those cameras could capture about twelve stops of light that's that red square on this so um medium format digital cameras can also capture about twelve stops of light and so that's why so many professional commercial photographers are using medium format cameras it's more for the dynamic range than the resolution. So it's it's a it's a really nice thing to have now our sl ours like my cannon ten d that I started out with years ago um or most cameras that we have that we can only capture about five stops only capture about five stops of light from the darkness to the lightest so you could see that what we see it's that big gray bar all the dark stow the lights camera sees not very much now what we're going to do is I need to see some cameras can do about six stops technically but we're going to talk a little bit about photons and why all this how this all happens and how come a medium format camera can capture more than a digital slr so what happens is light travels and it has it's actually made up of little things called photons so I've got chocolate candies and these are going to represent photons alright also photons are very tasty if you haven't had one um what happens is on your camera's sensor depending on what sensor you have, you have a bunch of little dots okay there's gonna represent the dots little dots are called pixels and more specifically there's little pixels or the dots anybody has zoomed in really close to a picture can see it's made up of little dots called pixels. Well, the sensor actually has these little devices that capture each of those pixels and those devices are called photo sites. Okay, so these are going to represent the photo sites and they're actually their physical wells and so they actually have cem cem dimension to them and as light comes in to the camera there's this reaction and so the photons hit those cells and then those cells actually captured the light and then it's translated into something that goes to a card by some magical way that some scientist knows about. Okay, the important thing is photons come through the lens, they come to a photo site and then they're collected and then later on they're transferred. Now the problem is getting all kind of camera you have if you have a camera with a, uh inexpensive sensor or a small sensor they have to so much more photo sites onto that sensor and so they tend to be smaller and that physical small limitation means that they can't physically hold as much light. And so what happens is let's say we're in a dim room and all we care about is capturing this dim scene well, there's not a lot of photons. So this guy gonna capture it, this guy sze going to capture it? This guy he's getting captured, right? So there's not a lot of dynamic range there, there's. Just like very consistent amount of luminosity of light. When we start increasing our contrast right, our light starts changing, we get things that are really bright and things were really dark. Well, thie amount of photons is more right. More photons coming in. Now, these guys here, you can start seeing what's gonna happen with you. A very small photo site on a small sensor. This is going to philip very quickly on a medium sized since or maybe like a five d mark two or full frame camera, you have mohr ability to capture mohr photons. You'll get more dynamic range and you also have less noise. And then you go to a medium format camera, large photo sites so you can capture all those photons so let's say, now you're out at the beach and you have a little bit of photons coming in for the shadows and you got a little bit for the mid tones but you got a lot for the highlights. A lot of stuff coming in. Here's what's gonna happen. This is the beach here's the photons. So the little camera that you have a point shoot? Uh, okay, all these photons out here this is what your camera can capture these air, the photons of the sky right there a lot. There's no ability can't capture that it's everywhere, right? This guy here, bill, bit more dynamic range, same scene. Nice. We got the whole scene with a medium format camera room. Despair. Okay, so the dynamic range of a large photo site is much better than this because this is going to become totally saturated. You can't get it back. It's gone the facts on a lot of medium format cameras. If you put those side by side with a dslr, you look at the history graham which were about to explain. You'll see that you have a lot of room on each side of the history getting a lot of room to play with on these little guys, not so much there's nothing you can do about that so dynamic range you have a couple of choices you can either by a forty thousand dollar camera that is not a choice I have to make, because I don't have that kind of cash so that's out, right? When you guys says forty grand to lend me, so you have the choice of getting maybe an upgrade to your camera, like, maybe something with a larger sensor or something that does a really good job with capturing those. So for example, the nikon d three, yes, and the newer sensors they've changed the photo sites, they have isos of crazy, like twelve thousand eight hundred, lulu is amazing stuff, so you can upgrade to a very expensive camera also, probably not an option for most people to going by a five thousand dollar camera, right? It's not gonna happen unless you're wealthy, which I don't think anybody s so we gotta figure out how to figure this thing out. We've got this to work with, so what we need to do is we need to be able to figure out how to shape our light so that we're taking the difference between the darkest and the lightest, and were compressing those things seen in photography, use filters and neutral density filters in the studio, we use different things, we use flags, and we use reflectors, and we use lighting ratios, and we use fill lights and all that kind of stuff, and so we're going to get into that heavy duty this afternoon that's the concept of dynamic range is how do we get all of this stuff in captured so I think we have a question coming in from the live audience is that right now I have a question no, I'm not getting you have a question from kingsley who'd like to know is the diamond dynamic range of a crop sensor with twenty one megapixel larger than a full frame with ten megapixel say that one more time is the dynamic range of a crop sensor with twenty one megapixel larger than a full frame with ten megapixel you're good question answer is no because what's happening is it's not always better to have a higher resolution camera this is a total misnomer so you might say okay I've got a uh dslr and it's got um forty let's say some crazy a minute megapixels okay, so that means that it has to physically fit all these little photo sites on this sensor that's fixed size so they're gonna be really small problems um if you have one that's like let's say ten megapixels or ate well there's physically more room on the sensor to put larger photo sites so you're dynamic range is gonna be better your noise is gonna be lower but your resolution isn't gonna be hot is high and specifically you can look at camera manufacturers and they have done this so nikon specifically, we've got the two flagship night concert today we have a d three x and a d three s the d three x has a full frame d three s has a full frame, the d three x is a much higher megapixel camera than d three s, and the reason for that is if you look at the d three x, it can't go to twelve thousand eight hundred s so it doesn't behave in would never take it and use it as a wedding camera or an event camera because it just doesn't have the ability to handle natural light. But when I'm shooting and I'm shooting for a commercial client, I need all those megapixels I know I can contain the dynamic range, so I go for the higher megapixel d three x don't worry too much about that, so you always have a compromise, and if we go to, like hasa blad or mias and face, when you start looking at those those backs, some of them are higher resolution and others and you can see that you have to always make that trade off. I'm going to go for the super high resolution with smaller photo sites, or I'm going to go for a little bit lower resolution with larger photo sites. Hey, mark, have a comment from a little crazy and the chap who says, wow, after this demonstration, I finally get dynamic range. Yes, good. Well, hopefully we're not even really, uh, we're gonna talk more about so, um, we're gonna clean this up. But have you are you have a question? What is the dynamic range on, say, aye computer monitor or also luster photography paper? I just want to see how that compares to or were the bottom that gives right view shooting, uh, medium format, you have twelve stops, can paper only cover eight? You know that? Sort of? Yeah, I don't know the answer to that specifically, but, um, when we talk about color let's, say that one talk about color because that's one of the considerations is you can have a dynamic range of capture of let's, say, twenty two stops. But when your final output, you might have problems with with that, specifically newsprint. You have big problems with that, and the same holds true of color.