Basic Photography Course

CHAPTER 3

PHOTOGRAPHIC FILTERS

Filters are used in all the various steps of the

photographic process. Though often neglected in the

shooting stage, the use of filters can tremendously
enhance the final product in both black-and-white and
color photography.

PURPOSE OF PHOTOGRAPHIC

FILTERS

The purpose of photographic filters is to alter the

characteristics of light that reaches the light-sensitive
emulsion As light is transmitted through a filter, at least
one of the following alterations occurs:

1. The color of light is modified.

2. The amount of light is reduced.

3. The vibration direction of the light rays is

limited.

The two most important reasons for using

photographic filters are to create an effect with an
emulsion and to control the exposure of an emulsion.
Interlocked with the use of filters are characteristics of
light and characteristics of photographic emulsions. The
effectiveness of a filter depends upon the ability of an
emulsion to respond to the color of light transmitted by
the filter.

Colored filters modify the way colors are recorded.

Without the use of filters, black-and-white
panchromatic film records colors as gray tones. These
gray tones correspond roughly to the tonal range as seen
by the human eye. Colored filters selectively brighten
or darken these tones. In color photography, colored
filters are used to correct or distort color balance.

Filters of a specific color transmit most of the light

of that color and partially or completely absorb light of
all other colors. For example, a red filter transmits red
light and may partially or completely absorb blue and
green light, depending on the deepness or purity of its
color (fig. 3-1). Likewise, a yellow filter transmits red
and green light and partially or completely absorbs blue
light. Remember, a secondary color of light is produced
by combining two primary colors of light. Red and green
equal yellow; thus a yellow filter passes red and green
light.

Figure 3-1.Red and yellow filters.

Filters are available in three forms: optical glass

disks bound with metal rims, lacquered gelatin film
squares, and glass squares. Glass disk filters are the most
practical for general use. They are available in different
sizes called series numbers, such as Series 4,5, and 6 or
in millimeter sizes, such as 52mm and 59mm. Glass disk
filters attach to a camera lens in two ways. Some have
threads and screw directly into the lens barrel, and the
others are held on the lens barrel by an adapter ring.

Gelatin filters and square filters made of glass are either
inserted into special filter holders that are part of the
camera, or they are held on the camera by a square filter

holder.

FILTER DESIGNATIONS

Filters are usually identified by numbers. This

system of designating filters is used to identify Kodak
Wratten filters. It uses designators, such as No. 6, No.
8, and No. 11. Some filters have a descriptive name
rather than a number; for example, polarizing, skylight,
and neutral density. Color compensating and color print
filters have yet another designation system.

3-1

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DOFMaster for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases.	contents <- previous page next page -> CHAPTER 3 PHOTOGRAPHIC FILTERS Filters are used in all the various steps of the photographic process. Though often neglected in the shooting stage, the use of filters can tremendously enhance the final product in both black-and-white and color photography. PURPOSE OF PHOTOGRAPHIC FILTERS The purpose of photographic filters is to alter the characteristics of light that reaches the light-sensitive emulsion As light is transmitted through a filter, at least one of the following alterations occurs: 1. The color of light is modified. 2. The amount of light is reduced. 3. The vibration direction of the light rays is limited. The two most important reasons for using photographic filters are to create an effect with an emulsion and to control the exposure of an emulsion. Interlocked with the use of filters are characteristics of light and characteristics of photographic emulsions. The effectiveness of a filter depends upon the ability of an emulsion to respond to the color of light transmitted by the filter. Colored filters modify the way colors are recorded. Without the use of filters, black-and-white panchromatic film records colors as gray tones. These gray tones correspond roughly to the tonal range as seen by the human eye. Colored filters selectively brighten or darken these tones. In color photography, colored filters are used to correct or distort color balance. Filters of a specific color transmit most of the light of that color and partially or completely absorb light of all other colors. For example, a red filter transmits red light and may partially or completely absorb blue and green light, depending on the deepness or purity of its color (fig. 3-1). Likewise, a yellow filter transmits red and green light and partially or completely absorbs blue light. Remember, a secondary color of light is produced by combining two primary colors of light. Red and green equal yellow; thus a yellow filter passes red and green light. Figure 3-1.Red and yellow filters. Filters are available in three forms: optical glass disks bound with metal rims, lacquered gelatin film squares, and glass squares. Glass disk filters are the most practical for general use. They are available in different sizes called series numbers, such as Series 4,5, and 6 or in millimeter sizes, such as 52mm and 59mm. Glass disk filters attach to a camera lens in two ways. Some have threads and screw directly into the lens barrel, and the others are held on the lens barrel by an adapter ring. Gelatin filters and square filters made of glass are either inserted into special filter holders that are part of the camera, or they are held on the camera by a square filter holder. FILTER DESIGNATIONS Filters are usually identified by numbers. This system of designating filters is used to identify Kodak Wratten filters. It uses designators, such as No. 6, No. 8, and No. 11. Some filters have a descriptive name rather than a number; for example, polarizing, skylight, and neutral density. Color compensating and color print filters have yet another designation system. 3-1 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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