فن التصوير .. المباديء والمنهاج -١٢- افلام الابيض والاسود مقومات ، انواع ومقاييس

**Ali Abbass** · 04-24-2023, 01:22 PM

art of photography . . Principles and curriculum, the twelfth lesson.
Black and white films components, types and standards

We talked about your camera and your lens, so let's talk now about the strange substance that causes everything to happen..!
It is the photographic film.
- In this lesson, you enter the field of black and white photography films.
And even for those who shoot in color only, it is necessary to read this lesson about black and white films, because all color films are captured in black and white in fact, although this may seem surprising at first, if this saying makes you confused and confused, then fortunately things will become clear All after completing this lesson.

Each film has two basic ingredients:
1- Light sensitive layer.
2- A base on which the sensitivity layer is applied.

sensitive layer:

The sensitive layer consists of Granules “a light-sensitive material suspended in a gelatinous lining, and the gelatin from the film is similar to gelatin in the common “Jello” material. This sensitive photographic material suspended in gelatin is silver halide. It is one of the silver salts resulting from the mixture of silver with chlorine or bromine. Or: pood, and the resulting compound is called silver chloride, or silver bromide, or silver abudide.
The silver granules are microscopically accurate. It is estimated that in a one-inch section of a sensitive film of a mild film there may be 40 billion grains of silver halide crystals.
These crystals have a special feature, which is that they change their structure when they are exposed to light, and here we do not need the exact chemical nature of this important change, which is the final result of it, because this change in structure is the basis on which photography is based almost in its entirety, from daguerrotypes. Nineteenth century - to today's high-speed movies.

How does change happen?
When you take a picture, light enters the camera and hits the photosensitive layer. When this light hits a silver halide crystal, the structure of the crystal changes and it clumps with other crystals. In those areas, where a larger amount of light falls on the sensitive layer, a larger number of crystals change and clump together.
In areas where less light falls, fewer crystals change and clump together. And so the difference
The optical forces that fall on the film are represented by the varying number of crystals that change their structure.

At this point, after exposing our film, we get what is called a latent image. - An invisible image - Then, to turn this invisible image into a permanent epitaph, we have to endorse the film. This process will be discussed in detail in a later lesson.

When the film appears, the crystals that have changed their structure are chemically transformed into agglomerates of black metallic silver to make the negative image. As for the crystals that did not fall on them and therefore did not change their structure, we are washed at the end with a chemical called hypo (hypo) during the endorsement process, leaving behind In their place are open and more transparent areas.
The result is a dark negative that is dense, in areas hit by light, and light. thin. In areas with less light.

- Al-Qaeda :

The sensitive layer that we described a moment ago must be coated on a base that will keep it together. At the time of La Gerotype, the base was a silver-coated copper plate. Today, the base of most films is made of cellulose triacetate, which is transparent and flexible. However, the emulsion can be applied to almost any solid material - paper, glass, cloth, etc.

The six-tiered structure:
The basic components of a film are the sensitive layer and the base. Most modern black and white films consist of six layers:
1- Cover: It is a layer of hard gelatin that protects the sensitive layer.
2- The sensitive layer with halide crystals suspended in a gelatinous lining.
3- Bottom adhesive layer (*): It is a layer of gelatin-like glue that attaches the sensitive layer to the base.
4- The base: It is also called the stent (*), and it is usually made of cellulose triacetate.
E- A second adhesive layer: It is like the lower adhesive layer, affixing the base with the adjacent layer.

6- Light backing: This backing that prevents light from escaping from the film is a layer that contains a dark pigment. When the film is exposed to light, this dye works to prevent the light from penetrating the film and then reflecting back to the film from a surface in the base layer - the support - or in the camera itself. In the days before light trapping appeared in films, reflected light would cause halos around bright objects, reducing the sharpness of the image. However, the pigment on the back, which prevents light from escaping, is dissolved with a hypo fixer during endorsement, so it becomes invisible on an endorsement film.
Note: In the year 1980, a new type of black and white film appeared. Elford - W. ACVA is based on a different principle called chromogenic imaging. Although these films, which are called Alford (1-XP) and Akfa (XL), produce a black and white image, they are based on the technology and chemistry of color film based on it. We will discuss it later in our lessons on colors.

Film types and standards:

There are four main types of films that you are likely to encounter: disc film, lap film. Covered edges film and slide film.

Disc movie:
When George Eastman built the first Kodak box camera around 1893, it was equipped with an implicit film in the shape of a circular cylinder. Every time you did an exposure, you exposed a tiny spot on the periphery of the disc, and the disc rotated to the next location, and then when you were done with, the frames, all on that periphery, you had to take the camera back to Eastman Kodak, in Rochester, New York, where the film was removed. It appears, prints, and reloads the camera with another disc film.
This film has not been around for long now, and was soon replaced by a film that could be removed and changed by the owner of the camera himself.
Kodak returned to follow this story again in 1983, when it came up with the newest invention in the world of film - the disc. In the middle, there is a plastic circle that holds the film in place inside the camera. Around the outer perimeter, there are 15 frames - each an 8 x 10 mm rectangle - that can be exposed. Around the inner frame are symbolic lines similar to the symbols you find on food packages in the market. , and it allows for automated acidification to be carried out by acidologists
Commercial.
It is a modern disc film that is installed and removed from the camera easily, by the photographer, of course.
It should be noted here that Disc Kodak film is not available in black and white, but only in color. We have previously noted that the Disc Kodak camera is made for the beginner amateur market in fact - snapshot capturers (*) - hence we assume that you will use this film a lot. However, we are addressing the descriptions here for your information only.

**Ali Abbass** · 04-24-2023, 01:26 PM

Lap movie:
The film is wrapped on a reel and has a protective paper on the back that protects it from light during feeding and removal. In addition, language film, size 120, is frequently used between large SLR cameras such as Hasselblad. The film produces 120 negatives with a height of 6 cm. The scale of the negative varies in other dimensions depending on the camera. There are three commonly used basic structures:

6 x 4.5 cm = 2 1/4 x 1 7/8 inch.
6 x 6 cm = 2 1/4 x 2 1/4 inch.
6 x 7 cm = 2 1/4 x 2 3/4 inch.

The traditional 6x6 format, which the Rolliflex (TLR) was responsible for popularizing, is now available in SLRs such as the Hasselblad 500c and Mamiya RB67.
Since the negative is square, this structure has the advantage of not having to turn the camera towards the sides to get a vertical shot. On the other hand, it is necessary to cut a good section of the negative if you want to get an 8 x 10 or 11 x 14 print.
It should also be noted that the 120-lap film produces 12 frames measuring 6 x 6 centimeters.
As for the newer structure, it is 6 x 4.5 cm, which requires working with a camera that is much smaller than 6 x 6.

Hence the cameras that operate in this structure, such as - Mamiya 465, and Pronica (ETL), which are noticeably smaller than their 6 x 6 counterparts and are intended to provide ease of portability and mobility as a 35 mm camera. In addition to the greater negative advantages.

What is meant by the 6x7 format on cameras such as the Mamba Universal Press and the Rapid Omega is the ability to perform the frills and stippling of a single view camera with the portability of smaller cameras. This is the current camera solution. The journalist and the interesting thing is that all of the 120 cameras mentioned here are SLR cameras, with the exception of the Rapid Omega, which is a field-finder camera. The Super Omega has retained its place in the world of SLR cameras because, as a press camera, it is characterized by its speed of handling and its solid manufacturing. There are photojournalists.

The 6th Lapse comes in two main roles: Film 120 and Film 220. Both of them have a width of 6 cm, but the 220 film has a paper backing from beginning to end, and by removing the backing from the middle of the tongue, the 220 film becomes able to wrap more film on a reel, thus occupying the same thickness. Hence, while Film 130 can produce 12 frames of 6 x 6 negatives in one language, Film 220 can produce 24 negatives in one language, while they are similar in other respects.
Most 120 film cameras feature a removable film back compartment for the camera, and the photographer owns more than one film compartment for such a camera.
He has added flexibility to his work, such as that he can put a black and white film in one booth and a color film in another, and each booth can be removed from the camera, although only part of the language has previously been scanned, without damaging the film, then the booth can be installed The other one, using it for a few shots, then removing it and putting back the first booth to expose the rest of her roll.

Another advantage of the removable film booth is concerned with the task of continuous, high-speed capture. While the cameraman is capturing one fim language in one booth, his assistant is busy impregnating another language in another booth, and when the language in the camera runs out, the cameraman removes the booth. We arise, to press the other in place quickly, as only a moment of time is wasted between shots, and in the meantime, his assistant removes the photocopied roll and replaces it with a new one, so that the process can continue without interruption.

Perforated Edge Film:
Perforated roll film is the type of film used in 35 mm cameras. It was a film that was mainly made for cinematographic cameras, but Oscar Bartak modified it in 1913 to be used in a new, small-bodied camera that he made himself, the first model of a Leica camera.
Perforated edge film is also available in 16 mm format for semi-compact cameras such as Minox ..

35 mm film comes in metallic cartridges of 20, 24 or 36 exposures and has been baptized. Ilford - Recently to a landing containing a 72-exposure roll. They were able to make this standard gauge cartridge using an extra-thin acetate base. It's basically a film made for the photographer who uses an automatic winder on their camera and can consume a 36-exposure roll in just a few seconds of
Quick capture.

The perforated roll 110 film is designed for pocket-sized cameras and is available in 12- or 20-exposure cartridges, producing a negative of 13 x 17 mm, while the 110 is designed primarily for point-and-shoot picture takers.
They are now available in models with electronic and optical functions that make them usable by serious hobbyists on occasion.

slide film:
Slide film is used in most large format studio cameras.
Its most common dimensions are 4 x 5, 5 x 7, and 8 x 10 inches. It is available in individual slides and in film boxes containing 12 slides each.

Next lesson
More about black and white films
and storage method

فن التصوير .. المباديء والمنهاج -١٢- افلام الابيض والاسود مقومات ، انواع ومقاييس

فن التصوير .. المباديء والمنهاج -١٢- افلام الابيض والاسود مقومات ، انواع ومقاييس

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