Basic Photography Course

of the slide, you must place the slide on the copy stage
horizontally, regardless of the composition of the slide.
When a full frame view is not desired, you can crop or
enlarge a portion of the original slide. When you change
the camera or lens distance to alter the image size, be

sure to refocus the image.

Examining Results

The duplicate slide should be laid on a light table

and compared to the original. If you bracketed your

exposure, determine which exposure provides the
correct density. When none of the exposures are
correct, the original must be recopied and given more
or less exposure by changing the f/stop. The exposure
time should not be changed. Again, bracket your
exposure.

Color Balance

Color compensating (CC) filters are used in a slide

duplicating camera. The CC filters are placed between
the original and light source. By changing the filtration,
you can correct the color balance of the duplicate slides.

After producing a duplicate slide with proper

density, the color balance of the duplicate slide must
be evaluated. When the color balance is off, you must
change it through the use of CC filters and re-shoot
the original. When the duplicate is extremely yellow,
first check the slide duplicating light source. Most
slide copy systems using tungsten light, have a "view
setting" and a "filter setting." If the system was set

in the view position, the CC filters were not in place.
The unfiltered tungsten light produces a slide that is
very yellow.

To judge the color balance of the duplicate slide,

lay it on a light table, compare it to the original, and
determine what color or colors are in excess. To do
this, you should view the duplicate slides through
various CC filters. A color print viewing kit is
convenient for this purpose. When viewing slides
through the various filters, look at the midtones, not
the shadows or highlights. Color viewing filters are
helpful in making color balance determinations. If a
color rendition chart was used as the original slide, a
densitometer can be used to directly compare the color
balance of the original to the duplicate.

To adjust the filter pack for the color in excess in the

duplicate slide, you should either subtract filtration of

Table 8-1.Color Compensating Filter Factors

FILTER

FACTOR

FILTER

FACTOR

05Y

1.1

05R

1.2

1OY

1.1

10R

1.3

20Y

1.1

20R

1.5

30Y

1.1

30R

1.7

40Y

1.1

40R

1.9

50Y

1.1

50R

2.2

05M

1.2

05G

1.1

10M

1.3

10G

1.2

20M

1.5

20G

1.3

30M

1.7

30G

1.4

40M

1.9

40G

1.5

50M

2.1

50G

1.7

05C

1.1

05B

1.1

10C

1.2

10B

1.3

20C

1.3

20B

1.6

30C

1.4

30B

2.0

40C

1.5

40B

2.4

50C

1.6

50B

2.9

the color in excess or add filtration of the complimentary
color to the color in excess. The amount of change
required is about the same as the viewing filter required
to make the midtones appear correct.

For example, when a slide is over in blue and

requires a CC20 yellow viewing filter to make the
midtones appear correct, a CC20 blue filter should be
subtracted from the filter pack. When a CC20 blue filter
cannot be removed, a CC20 yellow filter should be
added to the filter pack Your first choice should always
be to subtract rather than add.

Adding or subtracting filters has an effect on

exposure. To determine the exposure change required,
you should refer to the operating instructions for the
slide copier or consult a CC/CP filter factor table (table
8-1).

The number of filters used in a filter pack should be

kept to a minimum. Do not combine all three filters. This

only creates neutral density.

After processing, select the best exposure and use it

as the basic exposure for future duplicates. When you
copy other slides that are darker or lighter than the
reference slide, adjust the basic exposure. Use one-half

8-19

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Basic Photography Course

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