أجزاء آلة التصوير ١-a .. كتاب آلة التصوير

Camera parts

The copier consists of main parts that must be available in every machine, in addition to other parts that are either fixed to the machine or separate from it, which are considered improvements that distinguish some types over others. The following is a brief statement about these parts, which we list now as an indication, and we will be aware of the study of these parts in detail.

First: the main parts of the camera:

1- Camera Body: Regardless of the shape or size of the camera, the body of the machine is nothing more than a box sealed against light.

2- The lens: It is the glass part that collects the rays to record them on the sensitive layer. The second chapter will be devoted to explaining this topic in detail.

3- Diaphragm: some call it “the pupil” because it is similar in function to the pupil of the human eye, and it consists of thin plates that overlap each other (Fig. 6). In some primitive cameras (such as box cameras), there may not be a diafragm that narrows and widens, but the photographer controls the amount of light that enters the camera through a circular disc that usually has three holes of varying width. One of them is directly behind the lens. By turning the dial by one means or another (narrower or wider) behind the lens, the diaphragm performs three functions, which we describe as follows:

(a) Determining the width of the aperture through which the rays pass through the lens to the photosensitive layer. Hence, it controls the amount of light that is allowed to enter the camera. Diaphragm is associated with numbers called «focal numbers.f. No (Fig. 7), which indicates the ability of the lens to receive light whenever the diaphragm aperture narrows or widens (such as 22 f - 16 f - 11 f - 8 f - 5.6 f - 4 f - 2.8 f - 2 f .....etc). The greater the width of the diaphragm aperture, the decrease in the numerical value of the number of the focal length, so the focal number 2a indicates a relatively wide aperture, and the focal number 22 f indicates a very narrow diaphragm aperture. ...

(B) Controlling the depth of field, which is the distance in front of the lens in which objects have sharp images, despite the difference in the distance of these objects from the lens.

(c) Determine the passage of rays near the axis of the lens without passing near its perimeter. This function would overcome to some extent some of the natural optical defects in lenses.

We will come back to explain all these functions in detail.

4- Shutter:

Some call it blocking the light, and others call it the “convoy.” The shutter is the one that controls the time in which light is allowed to pass through the lens to the sensitive layer, meaning that it controls the speed of exposing the film to light, and this time may be, for example,
In addition to the numbers indicating the shutter speed, it is possible that in some cameras we will find two letters, T and B, and the shutter is set to one of them in cases that require an increase in the exposure time for more than one second. B stands for Brief Time Exposure. As for the letter T, it stands for Time Exposure, and the speed T is used when exposing a film that is sensitive to light for a long time, from five seconds, for example, to more than that. By pressing the trigger, the shutter opens and remains open until the trigger is pressed again.

(a) Between the pieces of glass housing the photographic lens, and it is called the Between lens Shutter, and it is sometimes called the Diaphragm Shutter. It was also named because of its close proximity to Al-Diya Farajim.

(B) In front of or directly behind the lens: We usually find it in this position in primitive or simple types.

(C) In the back, directly in front of the fifth layer, and by this type it is possible to obtain very high speeds that may reach 1 on 2000 of a second, and it is called the Focal Plane Shutter.

E - viewfinder: View Finder
Some call it a visualizer. It is a way to see the scene recorded by the lens. The means of seeing the scene differs according to the different types of cameras, as it may consist of two lenses whose axes are perpendicular, and between them is a mirror whose surface is at an angle of 45 with the axis of each of the two lenses (Fig. 9-a). Or the scene to be photographed is determined by ground glass at the top of the camera (Fig. 9-b) or by means of an optical viewfinder (Fig. 9-c).

And because the angle of view of the lens may change according to its focal length, and since many cameras are made so that their original lens can be replaced with other lenses of a different focal length, therefore a separate visual limiter is sometimes made that shows the limits of the scene whenever the focal length of the lens changes. It is called the Universal Finder (Fig. 21, p. 39). There is another type of visual finder that was commonly used in the past, which consists of a wire frame that is similar in shape to the shape of the negative, and is attached to the top of the lens. Behind it - at the level of the film - is a piece of metal with a hole in it. If we look through it towards the wire frame, it is possible to identify the scene that is recorded on the negative.