QUALITY OF LIGHT

There are two basic Qualities of Light we will learn to identify. 

1.     Specular Light (sunny day); also called Hard Light.  Characterized by hard shadow-edge transfer.  Look at the little shadow just below the baby's nose.  It is very hard edge. 

2.     Diffused Light (overcast sky); also called Soft Light.  Characterized by soft shadow-edge transfers to no shadow at all.  The shadows under this man's nose are much softer, to barely noticeable.

Additional Information:

1. A bright sunny day presents a specular light quality (the sun) and a ratio of 1:8.
2. A heavily overcast day presents a diffused light quality with a ratio of 1:1.  In this light condition there are no shadows cast; even, flat light.
3. A light overcast can have sunlight visible through the overcast.   This condition will cast light shadows.  This condition could be described as somewhat specular since it casts a shadow, but probably would be considered more diffused than specular in nature.
4. A cloudy day will present both qualities, specular and diffused, as the sun passes behind clouds and emerges again.   Exposures will have to change rapidly to accommodate the different amounts of light energy.  These are good times to rely on our automatic exposure features built into most of our cameras.

Quality of Light - the size of the source in relationship to the subject.

In other words, if I use a small light source  (like a portable flash unit or sunlight itself) and place it a fair distance from my subject, it will be small in relationship to that subject and will be specular in nature. 

But if that same light source is placed very close to a subject, it now (hypothetically) is large in relationship to the subject and it will be diffused in nature. 

I will use a nautical reference to make my point.  If I stand next to the main mast on my sailboat on the sunny side, I will be illuminated by specular light.  But if I move to the other side of my white translucent sail and the sunlight has to pass through the sail to illuminate me, there now is less energy falling on me.  You would have to adjust your exposure from BEF and the sail itself would become the light source.  This sail (light source) is now large in relationship to me which will produce a more flattering diffused quality of light.  Make sense?

COLOR OF LIGHT

Study this link on the Electromagnetic Spectrum  which begins with the following statement; "you actually know more about it than you think".  [See if you agree.] 

More simply stated, this EM Spectrum represents the visible and non-visible wavelengths of energy and frequency that we call light.  In photography, we mostly are interested in the visible spectrum which exists between 400-700 nanometers of frequency though our films are responsive to the non-visible wavelengths of x-ray, infrared.  A nanometer is one billionth [10-⁹] of a meter. 

Light energy travels in wave-like patterns (just as sound does) which are measured in nanometers.  A wavelength is measured by the distance between peaks of these waves. To use a familiar analogy, if ocean waves were light waves we would measure their frequency from the top of one wave to the top of the next wave.  The shortest wavelengths are found in the color RED which is why stop lights and stop signs are RED so that we can see them most immediately.  The longest wave lengths are VIOLET and the colors in the spectrum are broken down as follows from longest to shortest ; they are VIOLET, INDIGO, GREEN, YELLOW, ORANGE and RED (I use the acronym VIBGYOR).  This is also why warm colors advance visually (we see them fastest) and cool colors recede visually in photo compositions.  Prisms break light up into these basic colors just as rainbows do when visible in the sky. 

This link provides an EM Spectrum visual, along with a representation of the same ocean scene shot at different times of day (from sunrise to sunset) with Kelvin temperature light falling on the scene for you to visualize more effectively the concept of EM Spectrum.

 In photography, we have choices as to what time of day might produce the most interesting quality of light for our subject.  The color of our daylight shifts constantly throughout the day as illustrated in these photographs of the same building shot at different times.  This color of light is measured in degrees of Kelvin Temperature (a unit of absolute temperature equal to 1/273.16 of the absolute temperature of the triple point of water. One Kelvin degree is equal to one Celsius degree).

 Here is what you REALLY need to know:

 Films are designed to produce normal colors relative to specific Kelvin Temperature ranges.  Daylight films are designed for day light.  Tungsten films are designed to record normal values with tungsten lighting.  When we mix light source and film bases we will get color shifts.  That's why images taken indoors with house lamps shift to a warmish color value.

 1.    Daylight  equals 5500 degrees Kelvin temperature.  Our daylight films are balanced for this Kelvin temperature and will record 'normal' colors when we photograph under that color temperature range. 

     a.    Pre dawn light is a higher Kelvin temperature which renders images bluish on daylight film.

     b.    Sunset light is a lower Kelvin temperature which renders images warm yellow orange on daylight film.

2.    Tungsten light (household lamps, etc.) equals 3200 degrees Kelvin temperature.  When we photograph indoors using this light sources on daylight film, the images will appear very orangey yellow.  If we use Tungsten films (balanced for 3200 degrees Kelvin), the same photos will exhibit normal color values.

©Linda Lowell