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Angle of Incidence and Reflection

Lesson 9 from: Understanding Light & Light Modifiers

Mark Wallace

Angle of Incidence and Reflection

Lesson 9 from: Understanding Light & Light Modifiers

Mark Wallace

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Lesson Info

9. Angle of Incidence and Reflection

How can you control reflections in your image? What’s the best way to get rid of glare on glasses or other reflective surfaces? The answer lies in understanding the way light is reflected. Mark explains the angle of incidence and reflection using a laser pointer, a mirror, and some groovy sunglasses.

Lesson Info

Angle of Incidence and Reflection

one of the fun things about light is the way that it bounces off of things. And it's a very predictable thing that we can show and use. And it's a principle called the angle of incidence and the angle of reflection. And so I've created some charts and graphs here. Let me show them to you. So when we talk about the angle of incidence and the angle of reflection, if you look at this, the blue line here, that's the incident ray, that's the light coming from your light source, the sun, your flash, whatever the heck it is and the light, if it comes in at a 36 degree angle and it hits a flat surface, something like a mirror or something that's very shiny piece of glass, it will reflect at exactly the same angle where it came in on. So if it comes in at 36 degrees, it's coming out at degrees. If it comes in at 50 degrees it's coming out at 50 degrees. And so we're going to show you a few things about this and how it works now. This is really important. If you're shooting things that are high...

ly reflective, uh we're gonna shoot some stuff with some glasses, but if you're shooting highly reflective things like silverware or dishes or wine glasses or bottles or products, understanding how this works, it's important. So what I have here is a laser pointer and over here I have a mirror. In fact, I'm gonna turn this light off to make sure we can see things and then what we're going to do is we're going to first, let me show you what I have. I have a mirror right here and I have a laser pointer right here. We're gonna turn off all the lights in the studio room and out they go. So you can see that if I come in at this angle it's going to come out at the same angle, it's bouncing off that mirror if I'm gonna do this really fast. So you can sort of see that here you go. And as I move whatever angle I'm coming in at, as long as I keep it straight, it comes out at. So the angle of incidence and the angle of reflection are always exactly the same as long as the thing it's bouncing off of is flat. That's so cool. I could do this all day. All right. So when you turn the lights back on boom and I want to do is I'm gonna show you another thing that's really important because most of the things that we're bouncing light off are not flat. And so if we look at hard light reflectors most of the time they are flat because they want to bounce the light in a very predictable way. But when we look at a lot of soft boxes and some very specific light modifiers, I'm gonna bring this really close matt, Tell me when to stop. I think it's good. You can see that the texture on this. We have these little bumps. This is very uh silver. So it's highly reflective. Got all this texture here. Why is that? Well the reason that we have that is that it changes that surface. And so instead of having light coming in and bouncing exactly out of the same angle. Following that law. If you put little bumps, random bumps, what will happen is the light is going to come in and bureau go at random places because it's hitting that bump in a different place. And so it's going to scatter the light all around. So if you have a soft box like this and the light hits it instead of the light just bouncing one way it's gonna start scattering all over the place. And so it's gonna illuminate that front diffusion panel much more uniformly. And when it comes out it's gonna be soft, soft light. So the texture on the inside of your light modifier matters because it's going to either scatter the light or conversely it's going to focus the light and make it go in a very specific direction. So when you're looking at light modifiers not to look at the size of that light modifier and the shape of that that light modifier. But look at the texture of the light modifier itself, it will give you a clue as to how it's going to behave and what it's going to do with the light. Okay so all of our roadblocks. Soft boxes all of our allen Crum soft boxes have this texture on the inside, so we're not gonna open them all up to show you, but you can just understand that's what we're working with as we go forward. Okay, So it's time for Quinn to come back and Quinn is looking bad because she has these glasses that hard. Well, they're pretty cool. And so the thing about these glasses as they are absolutely flat, they're highly reflective. And so these are gonna be very problematic if we shoot them in the wrong way. All right, so, just have a standard there, we're exaggerating what's gonna be happening with these glasses, because we want to show you how to solve the problems in a predictable way. So, notice that my light I'll do this way, it's pretty much flat. So I haven't raised it. I haven't gone down. I haven't gone up. Haven't done any of these things. I'm trying to keep it pretty level and I have it pretty much at the same height as Quinn's glasses. Maybe I'll move that up just a little bit. And so, what I'm gonna do here is going to come over and meet her the light on Quinn. I think that light is gonna be who knows, F eight, F 10, something like that. So, I'm metering that F8, that's what it is. Okay, so what I'm gonna do is I'm gonna take a photo with the light at this angle. Now, remember the light is going to hit a flat surface and it's gonna come back the same angle. So right now we already know there are problems with this. So Quinn looked right at me. In fact, I'm gonna have you turn your head just a little bit. There you go, right there, stop right there, Perfect cappuccino. Well, this sort of looks cool, I think look at these glasses, you can see the reflection of the glass is the reflection of the light in the glasses? Absolutely. Now, what we can do is I'm not gonna move the light right now, I'm gonna have Quinn first, I'm gonna have to look at the light then straight at me and then a little bit over here. So first at the light bam straight at me, bam over there, bam now back at the light and lift your chin way up there you go. And then chin way down. There you go. There you go. Okay, let's look at these. So what we did is we change the angle of reflection by changing the angle of incidence. We'll look at this series of lights are of the photos so you can see that as she's looking different ways. We get either a lot of the glasses, a lot of the reflection in the glass is we get just a tiny bit right up here in the corner, that's showing up in the corner, there we get none, we get some we get nothing. Uh huh. So that's how it works. So, what we're doing is we're just changing those angles if you're doing maybe a corporate headshot or something like that and you have a person that has to wear glasses. This can be a problem because they can't just look around and be cool and look like Quinn and look sort of awesome. They have to look into the camera and so we don't have the ability to just have them move their heads around. What we need to do is we need to move the light. So what I'm gonna do, because I'm gonna take my camera, I'm gonna put it in one place, one place like this, I'm going to compose my image. Great, let's go a little bit higher and Quinn, what I want you to do is always look at the camera, just like that. I'm gonna make sure we have an issue, make sure we have an issue here. Okay. Yeah, so make sure you're always looking that way. So now what I'm gonna do is I'll take a shot this first shot, let's put this up on the screen, you can see that's not bad because we just have that little highlights in the corner of the glasses but if Quinn just happens to move ahead just slightly this way, they're not quite that much, just like they're right there. So say your subject just happens to move just slightly. We'll put that up on the screen, blah. What a difference. Just that little move made. All right. So let's say we have this bad, bad image here, we can make sure that doesn't happen by moving our light up. Point that down. We've just changed the angle of incidence. So now, unless she's looking up the lights going to come down and it's going to fall below the camera so that reflection should escape the camera. So I'll have the modeling light on so I can see for sure. But let's shoot. So, move your head about this way, a little bit of your head toward the light. Just a little bit like. There you go. There you go. Perfect. Now look what we just did we have. I think we did three images here. So here are the three images notice that all three of these would work as a as a corporate headshot. Okay, maybe not as a corporate headshot. All three of these images would work as a glare free photo. The only glare that we're getting are the only reflection that we're really getting is this little highlight at the top of this photo. And so it works pretty well. So, what I'm gonna do here is uh I'm gonna give you some different glasses. It's a complaint. They might not work. Try those glasses. I know you won't be able to see through them. And yeah, that looks pretty cool. So, what we're gonna do is we're gonna cause the issues again, I'm going to cause the issue, There we go now, this is much more of a sort of a corporate headshot. So look at that now. We have a librarian with a I that's been blasted by light. Okay, so I'm gonna do is I'm gonna raise up, raise up the light, point it down, raise up the light, pointing down. So by pointing the light down, I'm remember pointing this like down. Doesn't matter if it's hard, it's off, it's gonna make the reflections tend to go down. So up point it down to get those reflections down. We're just trying to play with these reflections and so I can see that even this isn't enough, I can see it almost instantly. And when we bring this in there it goes, you can still see whoops, you can still see her shoulder. Come on laptop. There we go, we still see that right there. So what I need to do is really make sure that I'm intentional about where I placed that light, maybe move it to the side, just a little bit, it looks like it needs to go up just a hair. There we go. And then I'm gonna have Quinn look just a tiny bit down just there you go, just a smidgen this image in and now look, we have solved the issue, it looks like there's no glass in those glasses at all. So not only did we fix the issue of the glare, but if you see these glasses in real life. So let's go back to the actual glasses in the photo. Sorry. Um not only did we fix the glare from the light, but if you saw these glasses in real life, they are covered in smudges and fingerprints and nastiness there scratch there. They've got all kinds of issues. But with zero Photoshop, no retouching at all, it looks like these glasses are pristine and I guarantee you they are not. They are nasty. So that is the angle of incidence and the angle of reflection. It will help you with reflections in glass and highly polished things. Anything that's shiny but it also hide blemishes not only on shiny things like glasses but skin and product surfaces, things like that. So if you start to see that you're getting um some glare or something that just doesn't quite work out. You might want to look and see if you need to change the angle of your light to your camera to control those reflections if you're paying attention. This is exciting because before we talked about the angle of light and how shadows were cast. Now we're talking about the angle of light and how reflections are cast and they sort of follow the same rules, just sort of on the opposite side of things. And so it's just more of the same angle of light stuff that will show you how that works with light modifiers. Now, the cool thing about light modifiers is remember if you have a larger light modifier and it is surrounding your subject, you might have more reflections to contend with. So if you see that, maybe it's time to change your light modifier to something that's softer, something that's smaller, something that's harder. It's up to you to decide. And so it's just something to be aware of. All right, we've got a lot more coming and so we're going to do that next.

Class Materials

Bonus Materials with Purchase

Bonus YouTube Videos.pdf
Frio Grasp Mini Discount.pdf
Pop Quiz.pdf
Sample Photos for Pop Quiz.zip
Tether Tools Pro Kit Discount.pdf
Tether Tools Starter Kit Discount.pdf
Understanding Light and Modifiers-presentation.pdf
NanLite_WALLACE5.pdf

Ratings and Reviews

user-a07413
 

Wow, Impressive with lots of information on light modifiers. Lots of variations of use and the bonus material. Mark is very good as a teacher. Glad I purchased the subscription plan so I can see the other Mark Wallace classes. Now to go to work and use the information.

Paul
 

I've heard much of this before, but this class really does a good job explaining and demonstrating the principles and techniques it covers. Mark is certainly quite knowledgeable, and he makes the material accessible and easy to grasp. It does cover quite a lot of ground, and while others may go into more detail, I think this class is great for building a good foundation.

Mario Furtado
 

Mark and his crew did an excellent job in this class. Now I am eager to see Go-To Lighting Setups and Studio Lighting Essentials. Congratulations.

Student Work

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