Lights, Camera, Reflection! How Understanding Angles Will Improve Your Photography

When they’re first starting out, many aspiring photographers skip the science of photography altogether.

They certainly don't worry too much about this or that law of physics dictating the behaviour of reflected light.

Instead, they simply experiment with their camera, trying different settings, subjects, and styles, and generally having fun.

Sounds good, right?

Trouble is, after a while, frustration sets in. Something’s not right. Despite having all this fun, these eager photographers aren’t getting the results they’re looking for.

No matter how hard they try, they can’t light their shots as effectively as they want to. Can't quite get to grips with reflection. They want to keep improving, but they’re stuck.

Sound familiar? If so, what can you do? The answer is simple: go back to the basics.

That's exactly what we're going to do in this article, revealing some essential photography tips along the way.

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subject flash point sun

© Karl Taylor

Learn how to position your lights correctly every time

If you’ve ever struggled to position a light correctly, or found your shots ruined by glaring reflections, you need to get to grip with angles – especially if you want to specialize in portrait or product photography.

The good news is, you don’t need a PhD in physics to capture better images. In fact, it’s all pretty simple when you break it down.

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Angles of Incidence and Reflection

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In this article, you'll develop a basic understanding of reflected light and the equal angles involved.

But before we tackle angles, let’s start by reflecting on reflections.

The four types of reflection

If you can see an object, it’s reflecting light. But different materials reflect light in different ways. Glass, for example, is reflective in a different way from skin.

Understanding the four types of reflection is crucial to improving your lighting techniques as a photographer and taking better photos.

1. Direct reflections

Direct reflections reflect the light source directly into your eyes. Or, if you’re looking through a viewfinder, into your camera lens.

These reflections occur when you direct light at a glossy material, such as acrylic (AKA plexiglass), water, or polished glass. They are ‘specular’ or ‘image-forming’. In other words, what you’re seeing reflected is an image of the light source itself.

Imagine standing in front of a mirror and pointing a torch or flashlight at it. You will see an image of the torchlight reflected back at you. This is a direct reflection.

angle incidence reflection photography
A direct reflection is specular or image-forming. Graphic © Karl Taylor Education

2. Direct unpolarised reflections

Direct unpolarized reflections occur when you illuminate shiny metals such as chrome or stainless steel.

This means that you can’t use a polarizing filter on your lens when taking photos of shiny metals.

left side, scene

Graphic © Karl Taylor Education

3. Diffuse reflections

A diffuse reflection occurs when you shine light on matt or textured surfaces such as wood, matt paint, concrete, a dry leaf, and so on. These surfaces cause reflections to scatter and diffuse in many directions.

Though you may still discern a reflection, you can’t see an image of the light source itself.

Diffuse reflection subject

Graphic © Karl Taylor Education

4. Combined reflections

Some materials produce a combination of direct and diffused reflections. Examples include leather and human skin.

When lighting these surfaces, you may still see an image of the light source, but it will not be completely clear due to the properties in the material that cause some diffusion.

A polished leather shoe, for example, may gleam considerably under a bright light, but will not reflect an actual image of the light source itself.

Image

Graphic © Karl Taylor Education

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Incidence and reflection: same angle every time

Now we understand the different types of reflection, we need to look more closely at angles. Why? Because understanding angles and their relationship to light is crucial to harnessing and optimizing reflections in your photography.

Fortunately, light behaves according to strict laws of physics. Once you’ve grasped these fundamental laws, you’ll find it much easier to decide how to light your subjects, shape your shadows, and optimize your images.

Here’s the most important law:

The angle of incidence is equal to the angle of reflection.

Let’s break that down.

Light strikes and light reflects off a surface at the same angle

Imagine a flat surface with a light shining on it. Now imagine an invisible line extending perpendicular (i.e. at right angles) from the point on that surface where the light falls. That invisible, so-called 'normal' line represents the ‘normal’ angle.

The angle at which the incident ray of the light strikes the surface of the object is known as the angle of incidence (i). The angle at which the reflected light reflects off the surface is known as the angle of reflection (r).

angle of incidence equals angle of reflection in photography, no matter the subject

Graphic © Karl Taylor Education

These two angles always mirror one another on each side of the normal. Hence the angle of incidence and the angle of reflection are equal – the same angle.

Knowing about equal angles is extremely useful when you want to make sure your light source reflects directly into your lens for maximum illumination. For example, in the illustration above, the camera is positioned precisely to catch the direct reflection.

Need a demo? Check out our simple trick using laser pointers to position your lights. It's all explained in Angles of Incidence and Reflection.

But what if you want to avoid reflections bouncing right into your lens? That is, what if you’re seeing too much glare reflecting off your subject, but don’t want to reduce the power of your lights?

That’s when you need to understand the ‘family of angles’.

The family of angles in photography

In photography, the family of angles is another useful means of working out where to position your light for a given shot.

The simplest way to think about them is to begin with the angle of view of your camera (also known as the field of view, or more simply, the camera angle).

Your camera’s angle of view is finite because it has vertical and horizontal outer extents. Put simply, just as we can only see what’s in front of us with our eyes, we can only see so much through our camera.

The angle of view is dictated by the size of your camera’s sensor, as well as by focal length, which is itself dictated by your choice of lens.

In the illustration below, the angle of view is delineated by two black lines extending from the camera to the subject. These lines strike the surface at a certain angle of incidence, relative to the normal (dotted lines), and bounce back off it at an equal angle of reflection.

Those ‘reflected’ lines extend back away from the surface, creating a ‘family of angles’ – effectively, a combination of the angles of incidence and the angles of reflection.

graph 3 object background one side photos flash other side

Graphic © Karl Taylor  Education

Any light (natural sun, flash, or continuous) directed at a reflective surface while also positioned within the family of angles will send reflected light directly into the camera. This will create visible spots of light in the image.

Sometimes, this is desirable. A good example would be the catchlights in the eyes of model (which are, of course, simply images of the light and modifier reflected off the eyes and into the camera).

Sometimes, however, the reflection is too strong, creating hot spots of excessive brightness and reducing the quality and effectiveness of the photo.

Here's a good example.

direction scene

© Karl Taylor Education

In a case like this, we need to simply remove the light sources from their position within the family of angles.

One way to do this is to move the lights themselves. But this may create new lighting problems. So if you don’t want to move your lights, you need to change the family of angles.

In the case of these wall tiles, we can adjust the family of angles by switching lenses to increase our focal length. This creates a narrower angle of view, which in turn produces a smaller family of angles.

graph focal length increased

© Karl Taylor Education

Now, the lights are outside the family of angles. This means no direct reflection strikes the lens, thus removing all unwanted reflections or glare from the image.

The result is a much more successful photo, with all of the vividness and none of the glare.

flash direction

© Karl Taylor Education

Get lighting right

That wasn’t so bad, was it? Who knew a photographer could find the physics of light so simple – and even fun?

Now you have a basic understanding of reflections and angles – specifically, how the angle of incidence is always the same angle as the angle of reflection – there’s no excuse not to control reflected light perfectly and get the lighting right every time you take a photograph, no matter the subject.

hot spots subject law lighting

© Karl Taylor Education

Need a demonstration?

Still not sure? Watch our Angles of Incidence and Reflection class to see it all demonstrated in a clear and accessible way.

In fact, we’ve got a whole section dedicated to photography lighting here on Karl Taylor Education. So if you need more guidance when it comes to mastering the science of light as a photographer, be sure to check out classes like Understanding Flash Power and Lighting Modifiers and Their Effects.

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