Male1: We now know how to properly expose for the diffused value of an image. Now let’s examine the concept of revealing shape, form, texture and mood. These elements can be controlled by the rates of change and the degrees of change between the diffused value on the shadow and the diffused value and specular highlight. Let’s first cover the rate of change or the edge transfer. The shadow edge transfer is the area of transition between the diffused value and the shadow. If the transition between the diffused and the shadow covers a small area will refer to the light quality as hard. If the area of transition is large we refer to the light quality as soft. The shadow edge transfer is one of the primary indicators that determines the quality of light produced.
Male2: Being based in Southern California, I often times will get components of ad campaigns or annual reports where they had different photographers around the world shooting for one collective project, yet they want every one to have similar lighting. They can email me a picture of an executive that was shot in Hong Kong I can look at it and tell exactly from the shadow edge transfer how it was lit and match that picture so all the images that I supply match the images they already have.
Male1: The predominant controls of the shadow edge transfer are the size of the lights source, the distance from the source to the main subject or object, the distance of the obstruction to the surface, and motion of the light source.
To illustrate the effects of the size of the light source on the shadow edge transfer Bill Holshevnikoff positions the 600 watt open face area light for dramatic back lighting effect on this table top set up. A black fly gets set to protect the camera lens from the lens blur. Holshevnikoff records the image of the light bulbs using the area light as the only source of illumination.
Our first image reveals the light quality produced by a small source of illumination. The shadow edge transfer covers a small area producing a hard light quality like that of raw sunlight.
To increase the physical size of the light source, Holshevnikoff attaches a small Chimera light tank to the area light. The light bank attaches to the instrument through the use of the Chimera speed ring, and the light bank can then be adjusted at any angle. With the light bank attached, light emitted bounces off the anterior silver reflect of walls of the light bank and it’s then transmitted through the front diffusion fabric to produce an even diffused source of illumination. With the light source still at the same distance from the table top, Holshevnikoff records the image of the light bulbs using the Chimera light bank as the only source of illumination. Looking at our first image the hard shadow edge transfer reveals the use of a small light source. With the addition of the light bank, the size of the light source increase and the shadow edge transfer increases dramatically in size. This increase on the size of the source produces a significant difference in the quality of light.
A study of this diagram will help to explain the relationship of the size of the source to the size of the edge transfer. With the small light source in placed the light path can be followed to reveal the shadow and the shadow edge transfer. With the addition of the light bank, the angle of cover just expands resulting in a larger shadow edge transfer.
And another example of shadow edge transfer control, Tinman-20 attaches the reflector to a pro-photo strobe and aims the strobe to illuminate our model Elena. A second strobe will an umbrella is set behind the model to eliminate the white wall. Then 20 then captures a few images of Elena using the single strobe as the only source of illumination for the subject area. The effects of using a small light source in our subject can be understood by analyzing the quality of light produced.
Illumination from a small lights source like the strobe produces a very hard quality of light on Elena similar to the quality of raw sunlight. To increase the size of the source of illumination introducing the Chimera light bank in creating a much larger source of illumination, and the large light source is aimed to illuminate Elena. The light source remains at the same distance from the subject. Man 20 then records a few images of Elena using the light bank as the only source of illumination for the subject.
In the first image Elena was illuminated by a small source of light which produced a hard shadow edge transfer. By introducing the Chimera light bank and creating a much larger source of illumination, one will expect a noticeable change in light quality, but the change is very subtle at this distance from the subject, and the shadow edge transfer remains relatively hard.
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