Basic Photography Course

copied with a film, such as Kodak Commercial film. An
original with a weak, faded image should be copied with

a film, such as Kodak Contrast Process Ortho.

SPECIAL APPLICATIONS IN COPYING

Special applications are used in copying to detect

information that cannot be seen with our eyes under

normal lighting conditions. Because these are special
applications, they are not performed in most Navy
imaging facilities, but are still worth mentioning. These
methods involve the use of infrared and ultraviolet
radiation and special types of films.

Black-and-White Infrared

Copying with black-and-white infrared films and

infrared radiation can help in deciphering old, charred,
or altered documents. This is possible because similar
appearing materials can reflect and transmit invisible
infrared radiation in different amounts. For example,
two ink signatures may appear identical to the eye.
However, when photographed with an infrared film, the
two signatures may appear totally different.

A suitable infrared filter must be used when

black-and-white infrared films are exposed. This is
because infrared film is sensitive to visible light as well
as infrared radiation. The infrared filter absorbs the
visible light so the film image is produced entirely with
infrared radiation. For specific filter recommendations,
consult the data supplied with the film or the Photo-Lab
Index.

Infrared wavelengths are longer than visible light

wavelengths and do not focus on the same plane as
visible light. Therefore, a slight increase in lens-to-film
distance is necessary. A separate focusing scale for
infrared is indicated on the focusing scale of most lenses.

Ultraviolet Radiation

Copying with ultraviolet (UV) radiation can aid in

detecting chemically erased or badly faded writing and
restoration or alteration of artwork because different
materials reflect or fluoresce different amounts of
ultraviolet radiation.

Photographing with reflected ultraviolet radiation

in total darkness is possible because some of the
ultraviolet absorbed by a material may be overlooked as
visible light or fluorescence. Such photography in
darkness is possible only when a material is illuminated

with an ultraviolet source, such as the General Electric
Uviarc. The fluorescence from a material illuminated

with ultraviolet radiation should be photographed with
a No. 2A (pale yellow) filter to absorb the stronger UV
reflections. A recommended film to use for ultraviolet
photography is Kodak Contrast Process Ortho film.
Exposure tests should be conducted to determine the
best exposure for an ultraviolet copy setup.

Do not use commercial ultraviolet lamps in which

the lamp itself is an ultraviolet filter. These lamps
transmit visible light that does not permit photographing
a fluorescing original.

COPYING REFLECTION ORIGINALS

Reflection originals are documents or other flat

objects like pictures or drawings that are viewed and
photographed (copied) by reflected light.

Copying reflection originals can be done with either

horizontal or vertical copy cameras or setups. The size
of the copy setup can range from the space necessary to
attach the original to a wall and make the copy photo
with a tripod-mounted camera, to a copy setup which
fills two rooms- one containing the camera back and
darkroom and the other the copyboard. Regardless of
the different copy setups possible for reflection
originals, the copying techniques are the same with few
exceptions. In general, the procedures used for copy
work are placing the original on the copyboard, aligning
the optical axis of the lens with the original, lighting the
original, focusing the lens, calculating the exposure, and
exposing the film.

PLACING THE ORIGINAL ON
THE COPYBOARD

A copyboard should have a positive means of

attaching and holding the original. The means of
attaching the original could be spring clips, small bar
magnets, thumbtacks or pushpins, a hinged glass frame,
a sheet of glass, vacuum, and so forth. When thumbtacks
or pushpins are used, be sure not to punch holes in the
original. For high volume copy, a vacuum copyboard
allows a more rapid change and positioning of originals
on the copyboard.

When you are using a vertical copy camera or setup,

a darkroom printing easel may be used to hold the
original in place.

ALIGNING THE OPTICAL AXIS OF THE
LENS WITH THE ORIGINAL

Arising, falling, and sliding front feature of a copy

camera provides for the alignment of the lens and the

8-13

contents

Basic Photography Course

<- previous page

next page ->


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 -> copied with a film, such as Kodak Commercial film. An original with a weak, faded image should be copied with a film, such as Kodak Contrast Process Ortho. SPECIAL APPLICATIONS IN COPYING Special applications are used in copying to detect information that cannot be seen with our eyes under normal lighting conditions. Because these are special applications, they are not performed in most Navy imaging facilities, but are still worth mentioning. These methods involve the use of infrared and ultraviolet radiation and special types of films. Black-and-White Infrared Copying with black-and-white infrared films and infrared radiation can help in deciphering old, charred, or altered documents. This is possible because similar appearing materials can reflect and transmit invisible infrared radiation in different amounts. For example, two ink signatures may appear identical to the eye. However, when photographed with an infrared film, the two signatures may appear totally different. A suitable infrared filter must be used when black-and-white infrared films are exposed. This is because infrared film is sensitive to visible light as well as infrared radiation. The infrared filter absorbs the visible light so the film image is produced entirely with infrared radiation. For specific filter recommendations, consult the data supplied with the film or the Photo-Lab Index. Infrared wavelengths are longer than visible light wavelengths and do not focus on the same plane as visible light. Therefore, a slight increase in lens-to-film distance is necessary. A separate focusing scale for infrared is indicated on the focusing scale of most lenses. Ultraviolet Radiation Copying with ultraviolet (UV) radiation can aid in detecting chemically erased or badly faded writing and restoration or alteration of artwork because different materials reflect or fluoresce different amounts of ultraviolet radiation. Photographing with reflected ultraviolet radiation in total darkness is possible because some of the ultraviolet absorbed by a material may be overlooked as visible light or fluorescence. Such photography in darkness is possible only when a material is illuminated with an ultraviolet source, such as the General Electric Uviarc. The fluorescence from a material illuminated with ultraviolet radiation should be photographed with a No. 2A (pale yellow) filter to absorb the stronger UV reflections. A recommended film to use for ultraviolet photography is Kodak Contrast Process Ortho film. Exposure tests should be conducted to determine the best exposure for an ultraviolet copy setup. Do not use commercial ultraviolet lamps in which the lamp itself is an ultraviolet filter. These lamps transmit visible light that does not permit photographing a fluorescing original. COPYING REFLECTION ORIGINALS Reflection originals are documents or other flat objects like pictures or drawings that are viewed and photographed (copied) by reflected light. Copying reflection originals can be done with either horizontal or vertical copy cameras or setups. The size of the copy setup can range from the space necessary to attach the original to a wall and make the copy photo with a tripod-mounted camera, to a copy setup which fills two rooms- one containing the camera back and darkroom and the other the copyboard. Regardless of the different copy setups possible for reflection originals, the copying techniques are the same with few exceptions. In general, the procedures used for copy work are placing the original on the copyboard, aligning the optical axis of the lens with the original, lighting the original, focusing the lens, calculating the exposure, and exposing the film. PLACING THE ORIGINAL ON THE COPYBOARD A copyboard should have a positive means of attaching and holding the original. The means of attaching the original could be spring clips, small bar magnets, thumbtacks or pushpins, a hinged glass frame, a sheet of glass, vacuum, and so forth. When thumbtacks or pushpins are used, be sure not to punch holes in the original. For high volume copy, a vacuum copyboard allows a more rapid change and positioning of originals on the copyboard. When you are using a vertical copy camera or setup, a darkroom printing easel may be used to hold the original in place. ALIGNING THE OPTICAL AXIS OF THE LENS WITH THE ORIGINAL Arising, falling, and sliding front feature of a copy camera provides for the alignment of the lens and the 8-13 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
	WWW.DOFMASTER.COM © 2006 Don Fleming. All rights reserved.