Sources of Photographic Lighting
Source
Ambient
Ambient light is existing natural or artifi cial light present in any environment. Ambient light can be subdivided into four major categories:
~ Daylight
~ Tungsten
~ Fluorescent
~ Firelight.
Daylight
Daylight is a mixture of sunlight and skylight. Sunlight is the dominant or main light. It is warm in colour and creates highlights and shadows. Skylight is the secondary light. It is cool in colour and fi lls the entire scene with soft diffused light. Without the action of skylight, shadows would be black and detail would not be visible. Most colour fi lms are calibrated to daylight at noon (5500K). When images are recorded at this time of the day the colours and tones reproduce with neutral values, i.e. neither warm nor cool.
Tungsten
A common type of electric light such as household bulbs/globes and photographic lamps. A tungsten element heats up and emits light. Tungsten light produces very warm tones when used as the primary light source with daylight fi lm. Underexposure occurs due to the lack of blue light in the spectrum emitted. The orange colour cast can be corrected with a blue fi lter if neutral tones are desired; however, correct colour can be achieved without fi ltration if used with tungsten fi lm. Digital cameras neutralise colour casts introduced by light sources other than daylight by adjustment of the white balance to the dominant light source or by capturing as RAW format and correcting in post production.
Fluorescent
Phosphors inside fl uorescent tubes radiate light after fi rst absorbing ultraviolet light from mercury vapour emission. The resulting light produces a strong green cast not apparent to the human vision. If used as a primary light source the results are often unacceptable due to the broad fl at light and the strong colour cast. Underexposure is again experienced when using this light source and the cast can be diffi cult to correct. Fluorescent light fl ickers and causes uneven exposure with
focal plane shutters. To avoid this shutter speeds slower than 1/30 second should be used.
Firelight
Light from naked fl ames can be very low in intensity. With very long exposures it can be used to create atmosphere and mood with its rich red tones.
Characteristics of Light
Light is the essence of photography. Without light there is no photography. Light is the photographer’s medium. The word photography is derived from the ancient Greek words, ‘photos’ and ‘graph’, meaning ‘light writing’. To understand light the photographer must be fully conversant with its qualities and behaviour. In mastering the medium the photographer learns to take control over the creation of the fi nal image. This takes knowledge, skill and craftsmanship. It can at fi rst seem
complex and sometimes confusing. However, with increased awareness and ractical experience light becomes an invaluable tool to communication.
Seeing light
In order to manage a light source, we must fi rst be aware of its presence. Often our preoccupation with content and framing can make us oblivious to the light alling on the subject and background. We naturally take light for granted. This can ometimes cause us to simply forget to ‘see’ the light.
When light falls on a subject it creates a range of tones we can group into three main categories:
Highlights, Mid-tones and Shadows.
Each of these can be described by their level of illumination (how bright, how dark) and their distribution within the frame. These are in turn dictated by the relative position of Subject, Light source and Camera.
Introducing light
The major difference between studio and location photography is the studio itself has no ambient or inherent light. The photographer starts with no light at all and has to previsualise how to light the subject matter and what effect that light will have upon the subject. Studio photographers have to conceive the lighting of the subject rather than observe what already exists. This requires knowledge, craft, observation, organisation and discipline. Good studio photography takes time,
lots of time, and patience.
Understanding the nature of light
In order to make the best use of an artifi cial light source, we must fi rst be aware of how light acts and reacts in nature. Observation of direct sunlight, diffuse sunlight through cloud and all its many variations will develop an understanding of the two main artifi cial studio light sources available. A spotlight (point light source) imitates the type of light we see from direct sunlight, a hard light with strong shadows and extreme contrast. A fl oodlight (diffuse light source) imitates the type of light we see on an overcast day, a soft diffuse light with minor variations in contrast and few shadows.
To understand light fully it is essential to examine its individual characteristics.
~ Source
~ Intensity
~ Quality
~ Colour
~ Direction
~ Contrast.
[the above material is from Photographic Lighting (3rd)]
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