الفصل الثاني ، ملحقات التصوير .. كتاب فن التصوير الفوتوغرافي

Chapter II

photography accessories

The camera constitutes the first stage in photography equipment, as it qualifies you to learn about the basics of photography and puts you at the beginning of the path of creativity, but your creativity and skill will develop with great capacity by using other photography accessories. Buy the accessories that you feel are necessary to develop your skill in the field in which you find yourself. Do not buy these accessories randomly and without prior planning, as buying unnecessary equipment may confuse you and scatter your efforts.

The most important accessories that may attract your attention the most are photographic lenses with different focal lengths. The lens that comes with your camera when you buy it is often standard in structure: 80 mm in 220 mm cameras - 120 mm in 35 mm cameras. 50 w

Any lens longer than these lengths is called a telephoto lens and any lens shorter than these lengths is called a wide-angle lens

Before we examine each of these lenses individually, let's take a look at how the lens works and the principles of image formation.

Lenses and light: Light travels in a straight line. This is a scientific fact that has become self-evident in our time, and had it not been for this fact, photography would have been impossible. It is also known to everyone that any lens collects rays of light and focuses them at one point. From the two previous facts, we draw the following conclusion: The light reflected from the subject enters through the lens in a straight line, so the lens collects it at one point, forming one clear image on the film sheet. Because light travels in a straight line, the image is drawn upside down on the film sheet.

Lens Structure: A lens is a circular prism that would form a circular image if the negative were not rectangular or square. Like any other prism, it suffers from the problem of decreasing illumination whenever we go to its edges, so it becomes the clearest image in the middle of the lens due to the passage of the largest amount of light in that region. The amount of light passing through the edges decreases, which reduces the sharpness and clarity of the image in those areas, and thus the problem of decreasing illumination appears. This problem may affect the quality of the photograph as a whole when using a very wide lens aperture, especially when making giant enlargements of the image, so the image appears sharp in the center and faded in the edges. For this reason, he cautions against using the widest aperture of the lens, and it is preferable to use two of the following apertures to ensure sharp edges. But don't think that you are making a mistake when you use the widest aperture of the lens, as the edges are faded and still exist, no matter how hard you try to prevent them from happening. All there is is that you mitigate the possibility of it happening. However, we saw pictures taken at the widest aperture, and their edges did not appear faded due to the photographer's ingenuity in controlling the lighting in the shot.

(1) Clarity: The ability of a lens or telescope to give a clear picture

Focal length:

Focal length refers to the size and degree of magnification of the lens. More precisely, we say that the focal length is the distance between the center of the lens and the film page when the lens is at infinity

Each lens has its own focal length, the standard lens is a focal length of 50 mm and the telephoto lens (telephoto 100 mm for example). It is twice the length of the standard lens and has a narrower angle of view than the standard lens. It can also bring distant subjects closer.

The lens When you decide to buy a lens, you must first determine the purpose for which you want to buy it. If you are someone who loves photographing birds in their nests on the tops of trees, you should buy a very long lens, such as 400 mm, the camera is 35 mm. And if you are one of those who like to photograph the face, then you should use a 135 mm lens, as it is most suitable to fill the frame appropriately without disturbing the model by getting too close to it.

Telephoto lenses:

There are three characteristics that distinguish telephoto lenses from other lenses:

1- The telephoto lens multiplies the effect of hand vibrations during photography due to its weight, and the longer the lens is, the more vibrations appear, and thus it produces blurred images.

When photographing with telephoto lenses, it is advisable to use speeds of no less than / 125 / sec to reduce the effects of vibrations, or to resort to a tripod for

The need for speeds slower than 125/sec. 2- Telephoto lenses are characterized by slow speed.

When we describe a lens as fast or slow, we mean that its maximum aperture is small or large. A fast lens allows more light to pass through it than a lens

The slow one. For example, a lens with a maximum aperture of 1.8 f is faster than a lens with a maximum aperture of 3.5 f, because it allows more light to pass through it. It is reported that the maximum aperture of the lens is engraved in writing on its interface

The light in the telephoto lenses to reach the film slide has to travel a longer distance than that which it transmits in the standard lenses, and the longer these lenses are, the greater the distance that it must travel. And if we know that the glass elements in telephoto lenses are twice as large as those in standard lenses, we know. The problem that the light faces when moving through the tele lenses, and therefore we learned the importance of the fast lens in transferring an additional amount of light to the film.

Depth of field: Telephoto lenses have a shallow depth of field. In a photo taken with a close-up lens, we notice that the objects in the foreground of the scene appear closer to the objects in the background than they are in reality. Even with the use of a small aperture to increase the depth of field, images captured with telephoto lenses remain distinguished by a shallow depth of field

There is no doubt that you think now, after we have explained the various restrictions that restrict the use of the telephoto lens, that this lens is not valuable, but you will find that its use is useful and enjoyable when you know how to deal with it appropriately, as it is like any other tool: easy if you know how to use it properly.