Basic Photography Course

Ease of operation in total darkness

A good quality enlarger is required to produce

high-quality color prints. Color enlargers used in Navy
imaging facilities are diffusion type of enlargers. Like

all image-forming equipment, the lens is an integral part
of the enlarging system. The lens used in a color enlarger
must be free of chromatic aberration; that is, it must be
a color-corrected lens.

COLOR TEMPERATURE

The color temperature of light used to expose the

color material must match the spectral sensitivity of the
color material. This is true when making the original
camera exposure, and it is also true when you are
printing color materials. In color printing equipment,

color temperature is usually regulated by adding filters
to balance the light source and by regulating the voltage

source supplying the lamp.

Corrective Filters

In color printing, three emulsion layers in the

printing material must be correctly exposed from the
three color images in the negative. The exposure of these
three layers is manipulated by both exposure time and

the color quality of the exposing light reaching the paper.
The color or quality of light is altered by placing color

filters in the light beam of the enlarger. You can use color

printing (CP), color compensating (CC), or dichroic

filters. CP and dichroic filters are placed between the
light source and the negative. Generally, dichroic filters
have replaced CP filters. Dichroic filters more
accurately control the light, and unlike gelatin filters, do
not fade over time. CC filters are placed between the
lens and the light-sensitive paper.

The filters that control the exposing light are called

the filter pack The basic filter pack differs among each
characteristic of color negative film; that is, film size,
manufacturer, film type, and film speed. For example,
the basic filter pack for 35mm Kodak Vericolor III
differs from the basic filter pack of 120 Kodak Vericolor

III. The basic filter pack for 35mm Scotchcolor differs
from the basic filter pack of 35mm Fuji color. The basic

filter pack for Kodacolor Gold differs from Kodak
Vericolor III. The basic filter pack for Kodacolor 100
differs from the basic filter pack of Kodacolor 400.

In addition to CP, CC, and dichroic filters, a CP2B

or equivalent filter is usually built into the enlarger to
absorb ultraviolet radiation emitted by the light source.

Voltage Regulation

Fluctuations in line voltage are more common than

most people realize. Power fluctuations affect both the
intensity and color quality of a light source. As little as
a 5-volt variation in the normal operating range
(l00-125volts) can change the output of a lamp by about

15 percent. This change in voltage results in a change in

the color quality of the light source. This variation is

about the equivalent of a CC10 filter.

To prevent voltage fluctuations, you must connect

the enlarger to a voltage regulator. Most voltage
regulators provide a constant voltage between 95 to 120
volts.

Two main types of color enlargers are in common

use by the Navy. The two color enlargers differ in the
way they control the exposing light. They are the

subtractive and additive printers.

SUBTRACTIVE PRINTERS

The subtractive type of color enlarger uses a dial-in

dichroic filtration system. This type of color enlarger has
three filtration controls that move yellow, cyan, and

magenta filters into the path of the exposing light.
Segments of the dichroic filters are moved in and out of
the exposing light beam on calibrated cams. This type
of filtration system provides accurate and repeatable
filter pack combinations.

Most color enlargers use a tungsten-halogen light

source. These light sources produce a great amount of
heat. When a tungsten-halogen light source is used, the
color printer must have forced-air cooling fans in
addition to the heat-absorbing glass. An ultraviolet
absorber, such as a Kodak Wratten Filter No. 2B
(CP2B), must always be included in the light beam,
preferably above the negative. The most common type
of subtractive printer used in the Navy is the Chromega

D dichroic enlarger.

NOTE:

Never touch a tungsten-halogen bulb.

Handle it only by the edges or reflector cone. Oil from
your fingers can heat up and create a hot spot on the light
bulb, causing it to burn out. If you touch the bulb, clean
it with a soft cloth and isopropyl alcohol. Allow the bulb
to dry thoroughly before energizing.

ADDITIVE PRINTERS

The additive type of color enlarger uses the additive

or primary colors of light (red, green, and blue) to
expose color printing paper. This type of enlarger uses

12-4

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Basic Photography Course

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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 -> Ease of operation in total darkness A good quality enlarger is required to produce high-quality color prints. Color enlargers used in Navy imaging facilities are diffusion type of enlargers. Like all image-forming equipment, the lens is an integral part of the enlarging system. The lens used in a color enlarger must be free of chromatic aberration; that is, it must be a color-corrected lens. COLOR TEMPERATURE The color temperature of light used to expose the color material must match the spectral sensitivity of the color material. This is true when making the original camera exposure, and it is also true when you are printing color materials. In color printing equipment, color temperature is usually regulated by adding filters to balance the light source and by regulating the voltage source supplying the lamp. Corrective Filters In color printing, three emulsion layers in the printing material must be correctly exposed from the three color images in the negative. The exposure of these three layers is manipulated by both exposure time and the color quality of the exposing light reaching the paper. The color or quality of light is altered by placing color filters in the light beam of the enlarger. You can use color printing (CP), color compensating (CC), or dichroic filters. CP and dichroic filters are placed between the light source and the negative. Generally, dichroic filters have replaced CP filters. Dichroic filters more accurately control the light, and unlike gelatin filters, do not fade over time. CC filters are placed between the lens and the light-sensitive paper. The filters that control the exposing light are called the filter pack The basic filter pack differs among each characteristic of color negative film; that is, film size, manufacturer, film type, and film speed. For example, the basic filter pack for 35mm Kodak Vericolor III differs from the basic filter pack of 120 Kodak Vericolor III. The basic filter pack for 35mm Scotchcolor differs from the basic filter pack of 35mm Fuji color. The basic filter pack for Kodacolor Gold differs from Kodak Vericolor III. The basic filter pack for Kodacolor 100 differs from the basic filter pack of Kodacolor 400. In addition to CP, CC, and dichroic filters, a CP2B or equivalent filter is usually built into the enlarger to absorb ultraviolet radiation emitted by the light source. Voltage Regulation Fluctuations in line voltage are more common than most people realize. Power fluctuations affect both the intensity and color quality of a light source. As little as a 5-volt variation in the normal operating range (l00-125volts) can change the output of a lamp by about 15 percent. This change in voltage results in a change in the color quality of the light source. This variation is about the equivalent of a CC10 filter. To prevent voltage fluctuations, you must connect the enlarger to a voltage regulator. Most voltage regulators provide a constant voltage between 95 to 120 volts. Two main types of color enlargers are in common use by the Navy. The two color enlargers differ in the way they control the exposing light. They are the subtractive and additive printers. SUBTRACTIVE PRINTERS The subtractive type of color enlarger uses a dial-in dichroic filtration system. This type of color enlarger has three filtration controls that move yellow, cyan, and magenta filters into the path of the exposing light. Segments of the dichroic filters are moved in and out of the exposing light beam on calibrated cams. This type of filtration system provides accurate and repeatable filter pack combinations. Most color enlargers use a tungsten-halogen light source. These light sources produce a great amount of heat. When a tungsten-halogen light source is used, the color printer must have forced-air cooling fans in addition to the heat-absorbing glass. An ultraviolet absorber, such as a Kodak Wratten Filter No. 2B (CP2B), must always be included in the light beam, preferably above the negative. The most common type of subtractive printer used in the Navy is the Chromega D dichroic enlarger. NOTE: Never touch a tungsten-halogen bulb. Handle it only by the edges or reflector cone. Oil from your fingers can heat up and create a hot spot on the light bulb, causing it to burn out. If you touch the bulb, clean it with a soft cloth and isopropyl alcohol. Allow the bulb to dry thoroughly before energizing. ADDITIVE PRINTERS The additive type of color enlarger uses the additive or primary colors of light (red, green, and blue) to expose color printing paper. This type of enlarger uses 12-4 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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