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Experimenting.. How to process images.. Book of photography

How to process images
Experimenting

A series of experiments remains the best way to get a correct idea of ​​the exposure required for sensitive paper in order to get a good image. When it comes to a professional display or a personal work, a series of experiments gives more useful information than a measurement method using a bosometer.

Unlike the latter, which only gives an estimate of the time required to expose the film to light, the experiment shows side by side sections of the final image exposed for different times. Since we use the same paper and materials for the experiments and for the final drawing, we can be sure that the general density, contrast and color tones in the final image will be identical to what we expected.

A few preliminary experiments with the enlarger will give you a correct idea of ​​the exposure time required to get an image with good density and contrast from a particular negative and paper of a specific type and gradation. When the negative is placed in its place in the enlarger, the experiment will be displayed in successive strips.

For example, we make five exposures side by side, increasing the exposure every five seconds: 5 - 10 - 15 - 20 - 25 seconds. Each strip should be wide enough to allow a theoretical judgment on the quality of the image. It is best to choose a distinct section of the image that contains a large range of gray values.

After processing (see page 192) the experiment will carry 5 strips of increasing density: perhaps one of them will be of the correct density while the other four will be either too light or too dense. If you estimate that the correct density is between two strips, it is sufficient to choose a stop and an exposure between the two exposure values.

The first experiment is usually made on paper with a normal gradation: if the experiment is too contrasting, you will then take a smoother paper and vice versa, if the experiment is smooth, you will take a contrasting paper. Note that the speed of the different gradations of paper of the same type (brand) varies considerably, so it is advisable after choosing a new gradation to make some experiments again. Usually you will know - by examining the negative in advance - whether you should immediately take a paper other than the normal gradation paper and make the first set of experiments with this paper.

For the work in progress, you can judge your drafts while they are in the fixing bath, which saves you time. If you wish to be absolutely certain of the final quality of the draft, you must judge it under daylight after complete fixation and washing with running water.

Experiments:

The method given below for making experiments before drawing or final printing is simple and deductive. Obtaining excellent pictures results from the choice of the negative film and from the way in which it is exposed with the aim of obtaining perfection. This method is suitable for all negative films and all sizes of pictures.

Examine the contact plate with a magnifying glass and choose the draft that best suits the negative.

Draw the negative holder from the magnifier and place in it the negative you have chosen: the dull side towards the lens.

Adjust the margin regulator to the required size. Turn on the magnifier and frame the picture.

Adjust the clarity as you adjust the drawing: watch it with a magnifying glass.

Adjust the pupil to 8/F or 11/F as much as the light of the picture is required for the exposure time you will give it. In case of doubt, rely on 10 or 15 seconds.

Place the red filter under the lens and then place a piece of sensitive paper under the margin regulator covering the different values ​​of the image.

Cover 5/4 of the sensitive paper with cardboard: Pull out the red filter and expose for five seconds.

Move the cardboard to 1/5 of the total area and expose for another five seconds. Follow the same procedure for the remaining three-fifths.

Experimental background: These sections represent exposures of 5 - 10 - 15 - 20 - 25 seconds. Each section is clearly different from the other.

Choose the experiment that gave you the most accurate image and then expose a whole sheet of sensitive paper for the same exposure time required to obtain the final magnification.