Basic Photography Course

Table 3-6.Filter Factor Equivalent Exposure Table

Example: The unfiltered exposure calls for l/60 second,
and the filter factor is 3. The correct exposure is 1/20
second (1/60 x 3 = 1/20 second). However, most
cameras do not have a 1/20 second shutter speed;
therefore, use 1/15 second or the next slowest shutter
speed.

3. When you are using an SLR camera with

through the lens (TTL) metering, put the filter on the
camera lens and adjust the exposure in the normal

manner. However, certain dark blue, red, and orange
filters may give faulty readings if used with TTL
metering systems because the meter reads 18 percent
gray. The camera light meter may not be sensitive to the
color of light passed by the filter.

4. Consult a filter factor equivalent exposure table.

(See table 3-6.)

DARKROOM FILTERS

No types of filters are used almost exclusively in

the photographic darkroom. They are safelight filters
and printing filters. The printing filters include variable

contrast filters for printing black-and-white materials

and color printing filters for printing color materials.

SAFELIGHT FILTERS

The word safelight in photography is used to

describe filtered tungsten illumination or direct
illumination from a sodium-vapor lamp. The color of a
sodium-vapor lamp does not affect (expose)
light-sensitive materials under prescribed darkroom
conditions. The word safe is misleading since light-
sensitive materials are never completely safe from

safelight illumination. The use of a safelight with some

types of light- sensitive materials is not recommended
Compatible safelight filters for use with certain
light-sensitive materials should be selected on the basis
of color sensitivity and emulsion speed of the material.
The best method of selecting a darkroom safelight filter
is to use the filter recommended by the manufacturer of
the light-sensitive material. Safelight filters absorb that
portion of the visible spectrum produced by a tungsten
lamp that would affect the light-sensitive material being
handled.

Sodium-vapor lamp safelights use sodium gas to

provide safelight illumination. Incandescent sodium gas
produces a very narrow band of visible light in the
yellow-orange portion of the spectrum. Colorblind
printing papers are not sensitive to this monochromatic
(one color) band of light, whereas the human eye is very
sensitive to it. Therefore, a brighter print room is
possible without the light affecting the printing paper.
By using specially designed filters that further reduce
the narrow band of sodium-vapor light, black-and-white
materials sensitive to green and red light can be handled
under this illumination. Table 3-7 provides some
examples for the application of safelight filters. Always
consult the Photo-Lab-Index to determine the best
safelight for use with various light-sensitive materials.

VARIABLE CONTRAST PAPER
PRINTING FILTERS

To obtain various degrees of contrast using variable

contrast printing papers, use a series of magenta and
yellow filters. The magenta filters are used to print
black-and-white negatives that are low in contrast.

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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 -> Table 3-6.Filter Factor Equivalent Exposure Table Example: The unfiltered exposure calls for l/60 second, and the filter factor is 3. The correct exposure is 1/20 second (1/60 x 3 = 1/20 second). However, most cameras do not have a 1/20 second shutter speed; therefore, use 1/15 second or the next slowest shutter speed. 3. When you are using an SLR camera with through the lens (TTL) metering, put the filter on the camera lens and adjust the exposure in the normal manner. However, certain dark blue, red, and orange filters may give faulty readings if used with TTL metering systems because the meter reads 18 percent gray. The camera light meter may not be sensitive to the color of light passed by the filter. 4. Consult a filter factor equivalent exposure table. (See table 3-6.) DARKROOM FILTERS No types of filters are used almost exclusively in the photographic darkroom. They are safelight filters and printing filters. The printing filters include variable contrast filters for printing black-and-white materials and color printing filters for printing color materials. SAFELIGHT FILTERS The word safelight in photography is used to describe filtered tungsten illumination or direct illumination from a sodium-vapor lamp. The color of a sodium-vapor lamp does not affect (expose) light-sensitive materials under prescribed darkroom conditions. The word safe is misleading since light- sensitive materials are never completely safe from safelight illumination. The use of a safelight with some types of light- sensitive materials is not recommended Compatible safelight filters for use with certain light-sensitive materials should be selected on the basis of color sensitivity and emulsion speed of the material. The best method of selecting a darkroom safelight filter is to use the filter recommended by the manufacturer of the light-sensitive material. Safelight filters absorb that portion of the visible spectrum produced by a tungsten lamp that would affect the light-sensitive material being handled. Sodium-vapor lamp safelights use sodium gas to provide safelight illumination. Incandescent sodium gas produces a very narrow band of visible light in the yellow-orange portion of the spectrum. Colorblind printing papers are not sensitive to this monochromatic (one color) band of light, whereas the human eye is very sensitive to it. Therefore, a brighter print room is possible without the light affecting the printing paper. By using specially designed filters that further reduce the narrow band of sodium-vapor light, black-and-white materials sensitive to green and red light can be handled under this illumination. Table 3-7 provides some examples for the application of safelight filters. Always consult the Photo-Lab-Index to determine the best safelight for use with various light-sensitive materials. VARIABLE CONTRAST PAPER PRINTING FILTERS To obtain various degrees of contrast using variable contrast printing papers, use a series of magenta and yellow filters. The magenta filters are used to print black-and-white negatives that are low in contrast. 3-10 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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