Basic Photography Course

standpipe to hold water in the sink at the correct depth,
yet still allow water to flow out (fig. 10-1).

SAFELIGHTS

The function of a safelight is to transmit the

maximum amount of light that can be used safely
without damaging the sensitized materials being
processed. The color sensitivity of different sensitized
materials varies. Therefore, the color and intensity of
transmitted light must be varied accordingly. A
darkroom safelight is the combination of a rated light

source and a filter designated to protect a specific
sensitized material.

The word

safe.

of course, is a relative term since no

sensitized photographic materials are ever completely
safe from the effects of safelight illumination. However,
a filtered light is accepted as safe when the sensitized
materials can be handled under the illumination with no
evidence of fogging for at least twice as long as the

normal processing time. No procedures must be
followed precisely when safelights are used:

303.23

Figure 10-1.Photographic processing sink

Use only the size of incandescent bulb specified;

for example, 7 1/2 watt, 15 watt, or 25 watt.

Handle sensitized material at the distance

recommended by the manufacturer. This is usually
between 3 and 6 feet.

To determine whether a safelight is safe, you should

follow these procedures:

1. In the dark, place a sheet of unexposed film,

emulsion-side

up,

on the working area where the film is

to be processed.

2. Place several coins on the emulsion and turn on

the safelight. Leave the safelight on for twice the length
of time the film will normally be processed.

3. Process the film normally and check to see

whether there is less density in the areas covered by the
coins. When there is less density, it indicates the film
was fogged by the safelight and the safelight is not safe.
A safelight that causes fogging may be corrected by
replacing the filter, by installing a lower rated bulb, or

10-10

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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 -> standpipe to hold water in the sink at the correct depth, yet still allow water to flow out (fig. 10-1). SAFELIGHTS The function of a safelight is to transmit the maximum amount of light that can be used safely without damaging the sensitized materials being processed. The color sensitivity of different sensitized materials varies. Therefore, the color and intensity of transmitted light must be varied accordingly. A darkroom safelight is the combination of a rated light source and a filter designated to protect a specific sensitized material. The word safe. of course, is a relative term since no sensitized photographic materials are ever completely safe from the effects of safelight illumination. However, a filtered light is accepted as safe when the sensitized materials can be handled under the illumination with no evidence of fogging for at least twice as long as the normal processing time. No procedures must be followed precisely when safelights are used: 303.23 Figure 10-1.Photographic processing sink Use only the size of incandescent bulb specified; for example, 7 1/2 watt, 15 watt, or 25 watt. Handle sensitized material at the distance recommended by the manufacturer. This is usually between 3 and 6 feet. To determine whether a safelight is safe, you should follow these procedures: 1. In the dark, place a sheet of unexposed film, emulsion-side up, on the working area where the film is to be processed. 2. Place several coins on the emulsion and turn on the safelight. Leave the safelight on for twice the length of time the film will normally be processed. 3. Process the film normally and check to see whether there is less density in the areas covered by the coins. When there is less density, it indicates the film was fogged by the safelight and the safelight is not safe. A safelight that causes fogging may be corrected by replacing the filter, by installing a lower rated bulb, or 10-10 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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