Kodak E-142 manual Tricolor Exposure Method

6.Adjust the exposure for the new filter pack. An exposure time that produced a print of satisfactory density may not produce an acceptable density when you change the filter pack. The following table gives filter factors for calculating exposure adjustments when you use KODAK CP or CC Filters.

Filter Factors for CP Filters

Filter	Factor	Filter	Factor
05Y	1.1	05R	1.2
10Y	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

To use the factors, divide the old exposure time by the factor for any filter you remove. If you add a filter, multiply the time by the factor. If you add or remove two or more filters, multiply the individual factors and use the result as your factor. You may need to modify these factors for your equipment.

Note: The filter factors listed in the table take into account the effects of filter surfaces.

When you adjust the filtration in equipment that has built-in dichroic filters, any noticeable differences in density are due to differences in the color density of the print. Suppose you have a print with acceptable density, but a magenta balance. When you add magenta filtration to correct the color balance, the print will become too light, so you must use a longer exposure time.

A rule of thumb for magenta dichroic filtration is to change the exposure time by one percent for every unit of change in filtration. For example, if you increase the magenta filtration by 20M, increase the exposure time by 20 percent. Changes in yellow dichroic filtration do not usually affect the apparent print density. If you use cyan dichroic filtration, use the filter factors in the table above as starting points for adjusting exposure.

Tricolor Exposure Method

Use KODAK WRATTEN Gelatin Filters No. 25 (red), No. 99 (green), and No. 47B (blue) to give the paper three separate exposures. Do not move the paper or the enlarger until you have made all three exposures. Typical exposure times for making an enlargement from a normally exposed negative are given in the table below.

	Times for an Aperture Setting of f/8*
Filter	for PROFESSIONAL ULTRA III Paper
	(6X Enlargement of a KODAK VERICOLOR III
	Professional Film Negative)
Red	3 seconds
Green	21.8 seconds
Blue	17.5 seconds

*For an enlarger equipped with a Photo Enlarger Lamp No. 212 or No. 302; the setting may vary with other types of lamps.

Evaluate the test print under light of the same color and brightness that you will use to display the final print. (See “Viewing”.)

Judge the print density first. If necessary, make another print by adjusting the exposure as recommended in the table below.

If your print is	Do this	OR	Do this
	Open the lens		Increase all
TOO LIGHT	aperture to
			exposure times
	increase the light
			proportionately
	level
	Close the lens		Decrease all
TOO DARK	aperture to
			exposure times
	decrease the
			proportionately
	light level

Then judge color balance.

	Subtract time		Add time to the
If your	from the
			exposure
	exposure	OR
print is			through
	through
			these filters
	these filters
CYAN	Red		Blue + Green
MAGENTA	Green		Red + Blue
YELLOW	Blue		Red + Green
RED	Blue + Green		Red
GREEN	Red + Blue		Green
BLUE	Red + Green		Blue

KODAK PROFESSIONAL ULTRA III Paper • E-142 3