Depth of field - what is it?

Nowadays photography becomes more common. However, it can rightly be considered a kind of fine art. However, art is unusual, because it requires not only a creative approach, imagination, but also technical knowledge.

Really highly artistic images can be done only on a good SLR camera. In this case, it is not enough just to possess such a camera, it is necessary to understand it. And that's where theoretical knowledge comes in handy. It is necessary to know what is the depth of field, the aperture and the diaphragm number, the focal length. Only owning theory, you can use the camera fully.

Basic concepts of photography

For a proper understanding of what the depth of field, you need to first determine the concepts of "focal length" and "diaphragm." We can say that the focal length is the main thing for removable lenses.

The focal length is the distance between the plane of the matrix and the optical center of the lens. In this case, the viewing angle of a specific objective is determined by the ratio of the focal length to the diagonal of the matrix. Accordingly, the shorter the focal length, the wider the viewing angle.

To understand what a diaphragm number is, you need to understand what the lens aperture is . It is essentially a hole through which light passes. In order for this hole to change, the diaphragm is made of several plates. When reducing these plates, the hole decreases, and light enters the lens less. When they dilute, respectively, light penetrates more.

The diaphragm number is an indicator that is inversely proportional to the diameter of the aperture in the diaphragm. It is denoted by the letter f. That is, when f has a small value, the aperture is wide open.

Now let's define what is the depth of field of the lens. This is the range of clear vision of objects that are in front of the subject and behind it. As it should be clear from the definition, much will depend on which object will be focused.

Depth of field depends on what?

Of course, it is very important for a photographer to know all the above-described characteristics of the camera, and also be able to control them. Depth of field can vary depending on several parameters. The main thing on which this indicator depends is the diaphragm number or the diameter of the diaphragm.

The dependence in this case is directly proportional. That is, the larger the diaphragm number, the stronger the depth of field. You can feel it yourself by taking pictures of the same object with different aperture. With a f / 22 diaphragm number, the depth of field will be greater than at f / 8.

Many may think that in this case it is better to take pictures with the maximum closed aperture, but this is not so. After all, it is not always necessary to get a clear picture to get a good photo. This is especially true in the case of portrait photography. Often to get a successful portrait it is necessary that the background is blurred. This is exactly what you can get by opening the wide diaphragm.

Or there are times when you need to focus on a particular part of the face. Then also shooting with a wide open aperture is used.

Also, the clarity of the image depends on the luminosity of the lens, that is, the maximum amount of light that can pass through it. Often for studio shooting, high-speed lenses are used, which have the maximum throughput.

If you are going to take pictures in the street in good natural light, then you absolutely do not need to acquire such a lens. Since natural light is enough to get photos with a clear image of objects.