What is the diaphragm in the camera?

At the first steps in the field of photography, difficulties often arise not only with arranging the exposure, but also with understanding the parameters that determine the quality image.

Aperture is one of three main parameters that affect the exposure of the frame. Therefore, without understanding the principle of operation, device and setting this parameter, it is quite difficult to create high-quality photographs of a professional level. for the correct use of the parameter and switching at the right time, you need to understand what the aperture in the camera is.

Understanding aperture

In order to simplify the understanding of what an aperture is for and what it is, it is often also called an aperture, relative aperture or aperture, we can draw an analogy with the human eye, more precisely, the pupil. The more dilated (open) the pupil, the greater the flow of light that the retina can perceive.

To build the exposure of a professional shot, three factors must be taken into account: aperture, ISO and shutter speed. Changing the aperture value controls the flow of light that the matrix or film perceives. This parameter varies depending on the subject, conditions, lighting, the desired result. Also, various indicators are used to achieve special artistic effects.

However, it is important to remember that a maximum open hole allows more light to pass through, while a more closed one allows less light.

What is a diaphragm and how is it arranged in the camera?

To determine the aperture, a special aperture scale is used. Yes, the camera display shows F /, followed by a specific numerical designation. This parameter characterizes how wide the open aperture is. The number is opposite to the opening level of the hole, that is, the smaller the number after the letter, the more the aperture is open. In order not to get confused in this pattern, it is important to understand the principle of action.

Aperture row has the following form

The transition from one value to another is considered one step. It is worth noting that one step changes the amount of light perceived by the matrix twice. Modern cameras also make it possible to set intermediate values ​​- one-third or one-half, for greater clarity.

Aperture structure

The modern diaphragm (iris) has the following components:

• Repeater;
• Bouncing diaphragm;
• Iris diaphragm.

Iris - includes several curtains (1), often from six to nine. They are driven by a ring (2) located on the lens, or by an electric drive (3).

Aperture design

If the diaphragm is fully open, then the hole has a round shape, and when closed, it has the shape of a polygon (4). The number of curtains affects this shape, that is, if there are more, the edges are more rounded, and this also determines the shape of the bokeh.

Boke shape

Leaping - a symptom that controls the aperture, installed in modern models of SLR cameras. It irregularly closes it to the selected aperture value at the moment the trigger is clicked. Due to which the image is projected before shooting with an open hole, this affects the convenience and quality of focusing.

Repeater - a special device with which you can forcefully close the hole just before the descent to the desired value.Most often used to check the depth of field before shooting.

What does the iris in the camera affect?

• DOF - depth of field of the image;
• The amount of light transmitted by the hole on the matrix;
• Image brightness and contrast;
• Image quality.

Effect on IPIG

The aperture affects, in addition to the luminous flux, the depth of field. When F is small, then the depth of field will be small, if F is large, then the sharpness is large. This is an important tool to control the point of attention in the picture.

It is important to be able to correctly use this opportunity to create boring accents, for example, when portrait shooting you need to focus directly on the person, while leaving the background blurry. Photographers engaged in macro photography especially deepen their understanding of the depth of field settings, for such frames a closed aperture is always used and the depth of field is significantly increased.

Example of shooting at different aperture values

Modern cameras allow you to focus on the subject and with the hole as wide as possible. At the time of shooting, the camera automatically closes the aperture to the desired value. To preview the image in closed hole mode, you need to use a diaphragm repeater. This makes it possible to view in the viewfinder to see what will be after closing the aperture.

Image quality and aperture

Aperture - control of the aperture parameter is used to achieve a sharper image. Based on practice, the maximum sharpness of the picture is achieved using average aperture values. This principle applies to all camera lenses.

If the aperture value is too large, then unwanted artifacts in the form of vignetting or aberrations may appear on the frame, if too small indicators there is a significant decrease in sharpness.

With a smaller aperture, image contrast increases. A large aperture makes it possible to view using the optical viewfinder. If the F indicator is lower than 5.6, then through the optical viewfinder, you can only view in good lighting conditions. With a larger aperture, the images will look richer and brighter, this is achieved due to a smoother transition of the dark areas to the lighter.

The effect of the aperture on the boke

Bokeh and aperture are directly connected. The best bokeh is achieved with the hole as open as possible, the shape of which is as close to round as possible. If the diaphragm is closed, the hole has the shape of a polyhedron, which is clearly visible in the blur zone. Such polyhedra are commonly called washers or nuts.

Budget versions of the lenses assume a small number of aperture blades, conceived of a maximum of six pieces, resulting in figures in the blur zone that resemble the structure of a nut. At a special price are lenses that are able to create circles of the correct shape due to the large number of aperture shutters. Modern models do not differ in a large number of curtains, but they are created in a more rounded shape, due to which the hole has the desired shape.

Effect of aperture on exposure

When changing the diameter of the hole, the exposure also changes. With a wide aperture, the matrix is ​​exposed more strongly, and the image becomes brighter. To clearly demonstrate the effect, several shots were taken with equal settings, but with different aperture values.

Aperture F / 2

Aperture F / 4

Aperture F / 8

Aperture F / 22

The following parameters were set for these frames: shutter speed 1/400, ISO 200, flash off, aperture changed from F / 2 to F / 22.

How to choose the aperture value in the camera?

How the diaphragm works and what it affects is already understandable, but how to control this parameter depending on the situation remains to be seen.

There are no clearly established rules in which it is indicated that it is necessary to use such a value and not a single step otherwise. Each photographer individually selects this indicator depending on what he is shooting, for what and in what conditions. However, to facilitate understanding at first, you can use some generalized tips.

If you plan to take pictures in low light conditions, then the f / 1.4 aperture is perfect. however, it is worth remembering that with this indicator a rather small DOF will be installed. Ideal for shooting small objects or creating soft focus if necessary.

Similarly, the hole diameter f / 2 is used.

Also in low light conditions, f / 2.8 is used. well suited for photographing portraits, since a depth effect is achieved that falls on all faces, there is no focus solely on the eyes.

The minimum value of the aperture at which worthy shooting of people is obtained is f / 4. In this case, a restriction on the operation of autofocus is set.

If you are photographing two objects (people), it is best to use the f / 5.6 value. If you need to take pictures in low light conditions, it is best to use an additional flash.

If you are shooting a large company of people or several objects that must be in focus, it is optimal to use the f / 8 indicator, this value provides good sharpness.

The vast majority of lenses guarantee maximum sharpness at f / 11, so this mode is well suited for portrait shooting.

When shooting under conditions of increased brightness, it is best to use f / 16, then a large depth of field is set.

For landscapes or urban photography, the f / 22 is well suited. When using this value, there is no special focus in the foreground.

Knowing the basic principles of operation and aperture settings, even a novice photographer will be able to properly arrange the exposure and get a high-quality photograph under various shooting conditions.