Basic Photography Course

302.290

Figure 10-27.Control strips read from center of each step with emulsion facing up.

DENSITOMETRY

A densitometer is an instrument used for measuring

and reading the density of film and paper directly. Film
is read on a transmission densitometer, and paper is read

on a reflection densitometer. Most densitometers

supplied by the Navy today have both transmission and

reflection reading capabilities on the same meter (fig.

10-26).

A densitometer uses a photoelectric cell to measure

the light transmitted through film or reflected from
paper electronically. Before a densitometer can be used,
it must be checked and calibrated against a reference
standard. To use the meter, you must place the material
to be measured, emulsion-side up, in the light beam
between the source and the photocell. The density
reading is then read directly from the meter.

There are several sets of filters incorporated in the

head of the densitometer. When you are reading
black-and-white materials, the yellow filter must be in
place. When color materials are read, there are two
different sets of filters that are used. They are Status A

and Status M filters. Status A filters are used to read
color transparencies and prints. Status M is used to read
color negative film that has an orange mask

Only certain steps of the control strip are read. The

steps that you are required to read are established by the
manufacturer of the material or are established by the
quality control technician within your imaging facility.
When you are reading the steps on your control strip, be
sure that the emulsion side is facing up and take the
reading from the center area of each step (fig. 10-27).

PROCESS CONTROL CHARTS

A process control chart provides a visual

representation of a process. Control strips that are
processed and read on a densitometer are then plotted
on a control chart. The points plotted on the graph
indicate what has occurred in the process at the time the
control strip was processed. Through the use of control
charts, a determination can be make whether the process
is operating normally. As stated before, only selected
steps of a control strip are monitored. For black-
and-white film, the minimum steps monitored are as
follows: base plus fog (B + F) or gross fog, high density,
low density, speed point, and contrast.

For each step monitored on a control chart, there are

three lines. The center line represents the mean (X)
(pronounced "bar X"), or average, a top line that
represents the upper control limit (UCL), and a bottom
line that represents the lower control limit (LCL).

10-41

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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 -> 302.290 Figure 10-27.Control strips read from center of each step with emulsion facing up. DENSITOMETRY A densitometer is an instrument used for measuring and reading the density of film and paper directly. Film is read on a transmission densitometer, and paper is read on a reflection densitometer. Most densitometers supplied by the Navy today have both transmission and reflection reading capabilities on the same meter (fig. 10-26). A densitometer uses a photoelectric cell to measure the light transmitted through film or reflected from paper electronically. Before a densitometer can be used, it must be checked and calibrated against a reference standard. To use the meter, you must place the material to be measured, emulsion-side up, in the light beam between the source and the photocell. The density reading is then read directly from the meter. There are several sets of filters incorporated in the head of the densitometer. When you are reading black-and-white materials, the yellow filter must be in place. When color materials are read, there are two different sets of filters that are used. They are Status A and Status M filters. Status A filters are used to read color transparencies and prints. Status M is used to read color negative film that has an orange mask Only certain steps of the control strip are read. The steps that you are required to read are established by the manufacturer of the material or are established by the quality control technician within your imaging facility. When you are reading the steps on your control strip, be sure that the emulsion side is facing up and take the reading from the center area of each step (fig. 10-27). PROCESS CONTROL CHARTS A process control chart provides a visual representation of a process. Control strips that are processed and read on a densitometer are then plotted on a control chart. The points plotted on the graph indicate what has occurred in the process at the time the control strip was processed. Through the use of control charts, a determination can be make whether the process is operating normally. As stated before, only selected steps of a control strip are monitored. For black- and-white film, the minimum steps monitored are as follows: base plus fog (B + F) or gross fog, high density, low density, speed point, and contrast. For each step monitored on a control chart, there are three lines. The center line represents the mean (X) (pronounced "bar X"), or average, a top line that represents the upper control limit (UCL), and a bottom line that represents the lower control limit (LCL). 10-41 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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