FAST FILTER FACTS

The primary colors of light are different from the ones for Paint and Ink.

They are:

Blue, Green and Red.

Their complementary colors are

Yellow, Magenta and Cyan.

Primary Colors: _ Complementary Colors"

BLUE ________ yellow (GREEN+RED)

GREEN _______ magenta (BLUE+RED)

RED ________ cyan (BLUE+GREEN)

FILTER LAWS:

1. A filter transmits its own color.
2. A filter absorbs its complementary color.
3. A filter of a complementary color transmits its two adjacent primaraies, and absorbs its complementary primary color.

For Black and White photography:

1. To lighten a color, use a filter of the same color.
2. To darken a color, use a filter of the complementary color.

Behaviour of light through filters:

• Transmittance- Light allowed to pass through the filter (A red filter passes red)
• Absorption - Light absorbed by the filter (A UV filter absorbs UV)
• Refraction - Bending of light passing through glass to air or glass to glass. Diopters, Prisms
• Diffraction- Bending of light passing sharp opaque edge. (Star filters)
• Diffusion - Breaking up of light rays from one direction into many directions,(Fog, Diffusion)
• Dispersion - Breaking up of light rays passing through different mediums. (Oil, etc.)
• Filter Types

Conversion Filters -

Used to convert Tungsten Color Film to Daylight (85 filter,Orange) or to convert Daylight Color Film to Tungsten Light (80A or 80B, Blue)

Light Balancing Filters -

The 81 (yellowish) and 82 (bluish) series are used to raise or lower the Kelving temperature of the light in smaller increments to match the balance of the film.

Color Compensation Filters -

Used singly or in Combination to get any color correction to any degree desired.

Polarizing Filters -

Used to remove reflections from non-specular surfaces. Also makes colors more vibrant by removing surface glare.

Nuetral Density Filters -

Used to reduce exposure. They absorb all colors equally.

Combination Filters -

Two different types in single filter, such as a warming filter and a soft, or cooling filter and a nuetral density. Cuts down on number of optical surfaces in front of lens.

Filter Factors:

These numbers, which are supplied with the filter, are used to adjust exposure multiply the number by the exposure or ASA of the film.

For example, a filter factor of 1.5 would reguire 50% more exposure. So you would open the stop by half, or slow the shutter speed by half a stop. Easiest way to work is to change the ASA on your meter to a number 50% lower. So 400 film would behave as if it were 300 film. A factor of two would require a full stop adjustment. You would rerate your film from 400 to 200.