The Edge of Light: Study light quality

May 19, 2010

Photo Tips

Model: Jenyne Butterfly © Eddie Tapp

[Editors Note: This week we have Eddie Tapp on a weeklong series titled “The Edge of Light” which is a series of articles on seeing light. We’ll have one article day starting today Sunday, and continuing all the way thru Saturday!]

If we could see light in the physical sense (such as we see a mass of water) it would become easy to determine the light quality by the volume density, direction and location. Kind of like watching the speed of sound, watching the ray’s of light can become a metaphorical quality or ability. The only means we have to see light in the literal sense is the source and destination. The objective is learning to see the light, notice the light quality and then how it becomes revenant to the chip.

Take a few minutes and become familiar with the following qualities of light: Specular Highlight, Diffused Highlight, Diffused Shadow, Hard Shadow…

  • A specular highlight is the brightest highlight on the image, easily noticed from chrome but more subtle on other surfaces. Look closely at a well done portrait that might be in your home. Take notice of the specular highlights on the skin tone, lips and the catch light in the eyes.
  • Diffused Highlight, also known as a Soft Highlight, is the area adjacent to the specular highlight and also the area that we would know as the color and tone of skin or any object. Often I will be asked to judge a professional photographers print competition along with 6 or 7 other judges and salon staff. The lights are setup to yield only the diffused highlight when viewing the images from 6 feet.
  • The diffused shadow (also known as the reflected light shadow) is the shadow area where detail, texture and color are visible and in most cases becomes the element of light that refines the shape and depth of your subject.
  • Hard Shadow doesn’t have to be and isn’t always visible in a photograph but when it is there, it can dramatically add a compositional element in the image. I think of this as me and my shadow. You know, it is the quality of light that will allow you to create funny animals with both your hands, the shadow that you see on the floor from a room light, the sharper the light source, the more defined the shadow is.

Look at the transition between a highlight and shadow region of an image, is there a delicate transition or there is there an abrupt transition between these areas? What determines this tradition include the softness or sharpness of light source along with the distance it is from the subject, and naturally the shape of your subject. Again, the further away the light source the sharper the edge of light will become.

Other attributes of light qualities to become familiar with are Direct Light, Ambient Light, Reflected Light and how these light qualities illuminate your subject. Take notice if you subject is being lit by low contrast light, high contrast light.

A portrait photographer will sometimes use 4 lights, a Main Light, Fill Light, Hair Light and Background Light and consider Lighting Ratios from the Main Light to the Fill Light such as 2 to 1, or 4 to 1 ratio. The Main Light will generate the specular highlight, diffused highlight and the hard shadow. The Fill Light will generate the diffused shadow. All of this is easily controlled using studio strobe setups.

Color Temperature of Light in Kelvin Degrees © Eddie Tapp

Visible Light has a color temperature that is measured as Kelvin Degree Temperature. The higher the number the bluer the image while the lower the color temperature the warmer the image. Daylight is considered to approximately 6500K and tungsten 3200K. However, the color temperature of daylight varies a great deal depending on the time of day and altitude, higher altitudes will have a cooler color temperature. We reference visible light color temperatures as skylight, tungsten, florescent and so on, each having a different Kelvin Degree Temperature. Specialized imaging devices allow the means to capture a greater light spectrum that the human eye can not see including X-Rays, Ultraviolet and Infrared light. It is within our Visible Light spectrum that White Balancing becomes so important.

© Eddie Tapp

© Eddie Tapp

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This post was written by:

- who has written 10 posts on The Digital Photo Experience.

Eddie Tapp is an award-winning photographer, lecturer, consultant, and author on digital imaging issues. With over 25 years of experience in computer technology, Eddie has been actively involved in educating and consulting corporations, studios and agencies in the applications of digital imaging workflow, color management, pre-press and digital photography globally through workshops, seminars, on-site consulting and training. He’s the author of Photoshop Workflow Setups and Practical Color Management, the first two in a series, Eddie Tapp on Digital Photography, published by O’Reilly Media.

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