التكبير والطبع الملامس .. كيف تعالج الصور .. كتاب التصوير الضوئي

Enlargement and contact printing .. How to process images .. The book of photography

How to process images
Enlargement and contact printing

There are two ways to print a negative: the first way is to make the negative image touch the sensitive paper and then expose the whole to light: it is contact printing. The second way uses an enlarger that projects the image of the negative draft onto the paper. This process is called the enlargement process and the image is called an enlarged image.

The image we obtained by contact has the same dimensions as the negative draft. For negative drafts that are 24 x 36 cm - for example - contact drawing is only used to create references. On a single sheet of 20 x 25 we can print all 36 images of 24 x 36 film or 12 images of 6 x 6 cm of 120 film. The best way to make a draft for the experiment by contact is to use a light box: the negatives are placed on the glass plate of the box and then covered with sensitive paper so that the two surfaces touch. A heavy piece of glass or metal is placed over them to ensure contact between the negative and the sensitized paper. After exposure, the paper is treated as shown on page 192.

Another, more popular method of making contact images is to use a contact printing plate placed under a light source: an enlarger, for example. These contact printing plates use a uniform measure of sensitized paper. This paper is slid under a glass and then covered with the negatives, so that the sensitized surface is in close contact with the weight of the glass plate. The exposure is made through the glass: the light passes through the negatives and reaches the sensitized paper.

- Magnifier

This machine is similar in some respects to a photographic machine. It consists of a head supported by a column fixed vertically on a wooden or metal base. The head contains a light source and a screen for broadcasting or, more often, a condenser. It also contains a holder for negatives and a lens of your choice of a good type equipped with a concealable red filter. When the negative is in place, the light is directed by the condenser through it and then passes through the lens to display the image on the wooden or metal base. To obtain a clear image, the distance of the lens and the illumination must be adjusted, while the magnification measurement is determined by the distance of the head assembly from the base. Exposure is obtained by placing a sensitive sheet of paper on the wooden base, usually in a margin organizer. Then expose it to light - without the red filter - for the appropriate period.

- Preparing a contact plate

Clean the puller bottle with a special material or with an antistatic rag.

In natural light, with your hands clean and dry, pull the negatives from their envelope while holding them by their edges.

Negatives are curved inward and opaque on the surface exposed to light and shiny on the other surface. Identify the shiny surface of each set of negatives.

Insert each set of negatives into the puller with the shiny surface touching the glass.

Under a light that has no chemical effect, place a sheet of paper in the puller with its sensitive surface touching the matte surface of the film. Close the frame.

Place the red filter under the lens, turn on the light and open the pupil to its maximum aperture. Raise the head of the magnifier so that the light beam illuminates the entire area of ​​the puller.

Change the pupil to between (8-11) and set the timer to about 10 seconds. With practice you will learn how to estimate the exposure time.

Turn off the magnifier, remove the red filter and expose to light. Open the frame and remove the paper that will appear. Leave the negatives in place so that you do not have to repeat the process if the images are not clear.