BOLEX S-221 Technical Information download pdf (Page 19)

Because coherent light is directional, intensity does seem to "fall-off" more quickly than with diffuse

light. This characteristic can be used to dramatic effect by placing a coherent light fixture very close

to the object or subject. The image will have a pronounced tonality shift even over a fair short

distance.

Drawbacks with coherent light should be apparent: scenes often have darker shadows and overall

higher contrast producing a wider range of light intensities. Reproducing an interesting range of

grays with coherent lighting is often more difficult. However, if coherent light is used to light a scene

head-on, the image can look flat and shadowless.

Don't expect the wire scrims that come with many lighting kits to significantly alter the nature of

coherent light. The harshness is more efficiently removed with thin spun fiberglass in front of the

fixture on a special mounting frame. Here's a list of some common coherent and semi-coherent light

sources:

Coherent

Semi-Coherent

Bright, Direct Sunlight Sunlight through slight haze

500 & 750 Watt Tota-Light (Tube Kit) Tota with spun glass

Common Household Clear Light bulb Frosted Household Bulb

Lowel or Colortrans Spot Fixture Spot with spun glass

Lowel or Colortrans Broad Fixture Broad with spun glass

PAR Type Spot Par Type Flood

Fresnel Spot (studio) Fresnel with spun glass.

Diffuse Light

The other type, diffuse light is usually a source of coherent light that has been reflected or refracted--

that is, bounced from an additional surface or directed through a translucent material like heavy spun

glass or frosted plastic. As a result, the light rays arriving at the object come from many more angles

and the shadows produced are much softer.

Tota-Light with

Umbrella Reflector

Tota-Light with

"Frost" on frame

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BOLEX S-221 Technical Information Page 19