التحكم بالاضاءة .. كتاب فن التصوير الفوتوغرافي

Lighting control:

The different shutter speeds that you use have a direct relationship to the light. In order to take a well-defined picture in poor lighting conditions, your regular film needs more light, and you will also need to use a slow shutter speed. But suppose that the subject you are photographing is moving and not fixed, so what will you do then?!

The camera has a tool or other means other than the shutter speed to control the amount of light falling on the film. This tool is called the aperture or iris because it is similar to the iris of the eye and works in the same way: when you look at a strong light, the iris of the eye narrows automatically in the strong light, and when you are in the dark, the iris widens automatically. Also, to be able to see clearly, and this is exactly what happens in the camera, the only difference is that you have to decide the appropriate lens aperture to match it.

All cameras have a lens hole, and in simpler cameras, this hole is a hole in a fixed piece of metal, or two holes in a moving piece of metal, in order to give the photographer more freedom of choice for the appropriate aperture. The iris of the camera, similar to the eye used in more complex cameras, is a group of metal feathers attached around the lens holder from the inside and superimposed on each other in the same way as in the aforementioned shutter slides. We control the opening or closing of the iris by means of a special ring for that, which is like the speed of the shutter, carefully measured and numbered. It opens and closes according to specific stops, and these stops are known by the letter F. In most cameras, you will find some or all of the following stops, depending on the type of camera:

P 12 P 19 - P , - P 3,5 - 4 - 5,6 - P 8 - P 11 - P 16 - P 22

It is important to remember here that the smaller number is for the larger aperture. For example, the aperture is larger than the F8 aperture. P 2.8 is

Another important rule to remember is that each aperture allows twice as much light to pass through as a smaller aperture next to it. For example, P-8 allows twice as much light to pass as P-11 and P-11 allows twice as much light to pass as P-16, but the F-5.6 aperture only allows half the amount of light allowed by P-8.

Camera producers, for more accuracy, made the lens aperture and shutter speed identical at work. Each of them halves or doubles the amount of light falling on the film whenever the lens aperture is moved from one place to another, or the shutter speed dial is moved from one speed to another.

Now let's contemplate this hypothesis: I was shooting still life shots using the f8 aperture and the shutter speed of 1/60 of a second taking the shots. Suddenly, you saw a subject moving quickly in front of you, so you decided to photograph it, so you adjusted the shutter speed to 1/125 of a second in order to freeze the movement of the subject, but if you only adjust the shutter speed, an incomplete amount of light will reach the film because you reduced the amount of light by half, and the result will be negative, underexposed. Negative This is why you have to adjust the lens aperture as well in line with the amount of lost light. What do you think the required aperture is? Yes, it is one aperture wider than the aperture you were using, i.e. 5.6.