آلة التصوير ذات ثقب الدبوس .. كتاب آلة التصوير

Pinhole camera:

Perhaps it has become clear from the previous introduction that the photocopy machine in its simplest form is nothing more than a box sealed against light, with a hole in its front, and that is why it is called a pin hole camera, and the image is formed in this machine as a result of the reflection of light rays on the surface of objects that It lies in front of the box, then passes through the hole and forms an inverted image of the body on the opposite surface, meaning that its bottom appears at the top of the image and its right is on the left side of it (Fig. 4).

The image area is affected by two factors:

1- The distance of the body or its closeness to Allah and the length of the extension of the box (i.e. its depth), so if the distance between the body and the hole is equal to the distance and the image, then the length of the image is exactly equal to the length of the body, and if the distance between the hole and the image is less than the distance between the body and the hole, then the image is less long than the body .

The image length can be estimated according to the following equation:

Image length = object length x distance between pinhole and image on
The distance between the hole and the body

For example, if we assume that the body is 100 cm long, and that the depth of the box (i.e. the distance between the hole and the image) = 10 cm, and that the distance between the body and the hole is 200 cm, then the length of the image is calculated as follows:

Image length = 100 x 10 by 200 5 cm. It is clear from the foregoing that the smaller the distance between the hole and the surface facing it on which the image collects (i.e. the smaller the depth of the box), the smaller the image will also be. It is evident that the intensity of the image brightness (1) increases whenever the depth of the box decreases, and that is because no change is made in the width of the hole through which the rays pass, because the amount of light that formed the large image in the case of the hole being far from the plane facing it is the same. The amount of light that formed the small image in the case of the hole being far from this plane. Therefore, the intensity of illumination of the image increases if the light is concentrated in a smaller area. In this case, the law of Al-Maxi applies, which states that the intensity of the image's illumination is inversely proportional to the square of the distance between the hole and the opposite surface on which the image is collected. If the diameter of the hole remains constant), the intensity of the image’s luminance increases and becomes 4 x. It has been observed that the hole allows only a very small amount of light to pass through it.
It is so wide that every point of light emanating from the body becomes represented on the image as a mixed light circle (Fig. E). Then the researchers considered replacing the expansion of the pinhole with a collecting lens for the rays. The setting of the lenses required making some changes in the shape of the box, so the back of the box was replaced with ground glass so that the image could be viewed and adjusted so that it falls on the focal plane of the lens. On the other hand, it was found that the simple lenses collected in their primitive form are full of optical defects, so it was necessary to make improvements in them. It was also found that it is necessary to control the time period in which light is allowed to pass to the sensitive layer, so a shutter was prepared for the camera (shutter).