Episode 011: Creative Use Of The Physics Of Light

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In this episode of CREATE. PHOTOGRAPHY, host Daniel Sigg will discuss how the physics of light. This in theory dry topic will hopefully become more interesting as we discuss how we can leverage some of the light properties creatively.

Featured image: Photo by Arthur Mazi on Unsplash

What is light?

Light is photons of energy.  It has both wave and particle properties.

Electromagnetic spectrum

Human see small portion of Electromagnetic Spectrum.

The portion of what is visible to us is between infrared to ultraviolet.

By !Original: PenubagVector: Victor Blacus – Own work based on: Electromagnetic-Spectrum.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22428451

 

I think it’s important to understand this with regards to color theory as it also relates to related and complimentary colors.

Example of Rainbow.

Properties of light

When speaking of light, we often refer to its properties.

These are:

Quantity  (also referred to as intensity or brightness. You will also hear the term luminescence.

Color

Light has a color temperature, often measured in Kelvin. There are colorimeters that can measure that.

Incident versus reflective light

Light that hits the subject = incident

Light that reflects off the subject = reflective

Incident light meter (bulb)

Reflective light meter (via camera or spot meter)

Quality

Photographers will use the terms “Hard” or “Soft” light = misnomer. It’s really more about the quality of the shadow and the transition of shadow to illuminated area.

The hard or softness of a shadow (a place where the light is blocked), depends on the size of the light source relative to the subject.

LIGHT RULE #1: The closer the subject is to the light source, the softer the light.

Ideally a much larger light source very close to the subject, will create a softer light.

Example: model and a 5 foot or 3 meter diameter Octabox or soft box.

Direction

Light waves do travel in straight lines. We can detect direction by the shadows and highlights.

LIGHT RULE #2: Most objects reflect or bounce off light waves. This is fundamental to understanding light. Therefore, they can by reflection illuminate indirectly other objects.

Non-translucent or non-transparent objects reflect light.

Brighter objects reflect more than darker objects.

LIGHT RULE #3: Surface quality of object determines type of reflection and how highlights are rendered.

Efficient / shiny objects create specular highlights.

Dull surfaces create much more diffuse or limited highlights.

LIGHT RULE #4: Angle of Incidence = Angle of Reflection.

With highly reflective objects, the angle the light hits an object will be the same angle it is reflected. The angle of incidence = the angle of reflection.

LIGHT RULE #5: color of an object is dependent on what colors are absorbed versus what is reflected.

Example: A banana is yellow because it absorbs all other colors in the spectrum and reflects only the yellow wavelengths.

Transparent and Translucent objects

Most objects are not transparent like windows. In transparent objects, like windows, light just passes through.

Windows can become translucent if they become dirty. So some light passes through, but some is scattered.

Refraction

Light can pass through some objects and be refracted or redirected.

Put a spoon or another object in a half-full glass of water, and you will see how the light is refracted differently as it passes through the air versus the water and the glass.

Camera lenses shape light through refraction.

Scatter

Under certain conditions, light waves can be scattered. This means light waves are bounced in different directions. For example, water droplets hit by the sunlight can create such light scattering.

Dispersion

Visible light can be separated into its component colors due to different degrees of refraction through an object.

Rainbow

Prism

Refraction

Visible light is bent as it is being transmitted

Shadows

Shadows are formed where light is blocked.

Photography and color

We are able to see colors in the “correct” color. In other words, our brains adjust to different lighting conditions where the temperature of the color (often measured in Kelvin) is different.

Cameras need to be told what the correct color is.

This brings us to the term white balance. Using white balance, we can set the color spectrum on digital cameras by using an index color (often a grey card) and then adjust the color spectrum accordingly. Of course, cameras can also do this automatically.

The white balance (and correct color temperature) changes throughout the day, changes under different weather conditions (cloud coverage) and is also very different under different artificial light conditions.

For those working with raw formats, white balance can be adjusted in post. For those film photographers who scan their negatives using a digital camera, the resulting raw files can still be adjusted as well, and often have to be adjusted to represent the colors as closely to life as possible.

After a lot of theory, let’s talk about some easy and creative ways to play with those light physics

White balance

Try once to change your white balance. If you are a purist, or a documentary photographer, you may not want to use this technique. But as a creative tool, adjusting the white balancing can create some pretty interesting effects.

In fact, this is not necessarily limited to digital photography.  You can also digitize film negatives in raw format and adjust white balance accordingly.

shift to cooler tones: blues

shift to warmer tones: warmer tones

 

Reflections

Is its own (big) topic

Again, more efficient (or shiny) objects are creating more reflections.

For example, if we are photographing buildings with lots of glass and perhaps even chrome, we will be dealing with potentially lots of reflections. We can use this to our advantage, and put something of interest in your reflection.

We can work with mirrors, and use the mirror and what they are reflecting  as our compositional element.

Of course we do not have to look for traditional mirrors, if we are doing  street photography, we can look for reflections in car mirrors or on shiny / reflective cars, or glass of buildings.

Reflections in puddles and other bodies of water can be cool compositional elements. We can create symmetries, or we can also just use the reflective portion of the image and not even include the object that is being reflected.

Reflections of the sky in bodies of water are nice, and of course.  The sky is literally the limit with all the options here as it relates to reflections.

Shadows

You could look for shadows, and try to make this into a little project. Perhaps just focusing on the shadows.

If there is a light point light source like the sun, or a strobe (without modifier) that is relatively small compared to the subject, then we may see strong shadows.

Shadows offer very interesting additional compositional elements to make images more interesting. Sometimes it is the shadow within a nature structure like a mountain that makes the mountain in that case more 3D and creates more depth.

Using shadows, often with people, is very popular in street photography for example.

Light direction

a topic for its own, but very important as well for creative effects. I am also referring to the discussion we had with Don Giannatti on the topic of lighting in episode 9.

See danielsiggphotography.com/episode009

Translucency

Translucent objects are very interesting compositional elements.

I am referring once again to the work by Saul Leiter. Many of his photographs are taking from the inside of a fogged up/condensed coffee shop window. The condensation on the window creates a layer that is translucent. So the reflecting light beams from the outside objects are further refracted by the water droplets on the window, creating a painterly effect. It also results in not recognizing the object as clearly, it removes sharpness, again adding to the mystique of those type of images.

You can create similar effects by shooting through window curtains or other textiles for example. I love the look of this type of layering.

Scatter

As mentioned, scattering means that light is bounced in different directions. For example, water droplets hit by the sunlight can create such light scattering. Another common example is the sunlight scattered on bodies of water, creating a glistening effect.

So what are some creative ways of using scatter. For example, you could photograph droplets that are being illuminated by the sun and you might be able to get strong scatter.

You can photograph those same droplets and look for refraction of the image … the droplets would act as a sort of lens and represent what’s behind it, typically upside down.

Lenses can scatter light in a way that we see as lens flare. Lens flare can be incredibly annoying or can be used for creative effect. With older lenses we have to be careful to photograph into the sun as those lenses are not as flare resistant.

Lens flare is very popular these days in cinematography. Check out A star is born with Bradley Cooper and Lady Gaga. Cinematographer Matthew Matthew Libatique used this effect a lot.

Diffraction

We have not talked about lens diffraction yet, but I thought I bring this up briefly as it is the phenomenon whereby smaller apertures diffract the light. We can use lens diffraction creatively by creating sunstars of the sun or street lights or other point source lights by stopping down our lens do higher values like f16 or f22. Lens diffraction can also create less sharp images.

I think the list of how to use light creatively is endless, as in photography we are dealing with capturing images that are illuminated.

But it is fun to think about specific technique where we perhaps focus creatively on certain aspects of light behavior/physics.

 

Thanks so much for listening! 

 

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