الكاميرا احادية السكة .. اختيار واستخدام المواد .. كتاب التصوير الضوئي

Single-rail camera .. Selection and use of materials .. Book of photography

Selection and use of materials
Single-rail camera

In all photographic machines, the lens is focused on the center of the film and the optical axis is perpendicular at the same time to the lens holder and the back of the machine. For a professional machine equipped with movements, this position of the lens in relation to the film is considered "normal position" and then the movements are said to be in zero position. However, the movements of the single-rail camera allow for the control of the clarity and perspective of some subjects, including architecture and still life.

- Camera movements

In the single-rail camera, the position of the front of the body (which carries the lens) and the back of the body (where the film is located) can be controlled separately, which brings great freedom in preparing the image: control the depth of field, increase the clarity area, re-frame without rotating the entire machine, etc.

These photographic machines use large-format films, which are themselves large in size and are always used on supports.

Each body of this machine can rotate according to a horizontal axis or a vertical axis (because there are vertical and horizontal glasses) and move horizontally (horizontal lens deflection) or vertically (vertical lens deflection). If the machine is tilted sideways 90°, the vertical movements become horizontal and vice versa. In short, the movements of the single-rail camera are as follows: vertical and horizontal swing for each of the two bodies and vertical deflection (up and down) and horizontal (right and left) for each of the two bodies.

If the foreground or background object is rotated or changed, the image displayed on the opaque glass, i.e. the focusing glass, is modified. This requires, in most cases, that the field seen by the lens be wider than the field required for a machine with no movements. We often use several movements: front neutralization and back swing, for example.

Horizontal swing:
The horizontal swing movement of the background object modifies the shape and perspective of objects: in this case, some parts of the subject are enlarged more than others, which modifies their proportions. The front horizontal swing of the background object does not modify the perspective, but it affects the change and the depth of field.

Vertical swing:
The movement of the background object modifies (as was the case with the horizontal swing) the shape and perspective of objects. In general, the back vertical swing monitors the parallelism (on the image) of the subject's vertical lines, while the front vertical swing monitors the clarity.

Lateral neutralizations
When working on one object without touching the other object, we change the position of the image on the opaque glass, which requires that the lens has sufficient coverage. Neutralization allows the image to be reframed horizontally without rotating the device, i.e. without changing the perspective.

Vertical neutralizations
They work like lateral neutralizations, but they change the position of the image upwards or downwards. If the machine's column is horizontal (and the objects are not swayed), the vertical neutralization allows the image to be reframed (a picture of a tall building, for example) without even the machine, so without bringing the image closer to the vertical lines of the subject.

- Deleting an unwanted detail:
By taking a point of view that is skewed to the right, the first level has completely disappeared, but the window is in the middle of the image. By using the side neutralizations (front and back) in the opposite direction, I was able to return the window to the center of the image while preserving the rest of the compositional elements.

The main factor in a scene of a picture is the chosen point of view. For the picture, the machine (all its movements are at zero) was placed opposite the subject and the window was in the center of the image. However, there were some important details hidden behind the flower bed on the first level.

- Schimpflach's rule:

If we extend the levels of the subject, the film and the lens holder, they must intersect successively in a single line. This will give you a subject that is evenly distributed on the main plane of the subject. In other words, applying the rule gives the greatest possible depth. To publish that Objects placed close to the film plane can be distorted. We see in this drawing that the Schimpflach condition is respected here only by using the front body swing and the rear body (in this case) remains perpendicular to the machine shaft.

Horizontal swing

1 - Backward swing to the left

2 - Backward swing to the right

3 - Frontward swing to the left

4 - Frontward swing to the right

Vertical swing

5 - Backward swing to the back

6 - Backward swing to the front

7 - Frontward swing to the back

8 - Frontward swing to the front

Side neutralization

9 - Backward neutralization to the left

10 - Backward neutralization to the right

11 - Frontward neutralization to the left

12 - Frontward neutralization to the right

Vertical neutralization

13 - Upward rear neutralization

14 - Downward rear neutralization

15 - Upward front neutralization

16 - Downward front neutralization

Single rail camera and accessories

Magnifier for calibration
Phosometer
Flexible bellows
Black diaphragm
Reel film frame
Instant film frame
Size divider
Flexible button
Double lenses
Interchangeable lenses
Filter holder