Aperture In Photography Complete Guide (water effect, light sources and more)

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The right aperture:

For many camera users, the aperture is a book with seven seals. But once you have understood the principle of the aperture, it is no longer so difficult to use it correctly and to always find the right aperture value.

In order to use the advantages of an aperture and its properties on a specific subject, it is important that your camera allows the aperture to be set manually. This is the only way you can take advantage of certain properties and give your pictures a very specific mood.

The aperture regulates the amount of light that hits the image sensor through the lens and is indicated by the letter “f”. In your camera display, next to the shutter speed of 5 seconds, for example, there is a value f5.6 or f8.0.

One can easily compare an aperture with the pupil of our eye. This also opens or closes in order to regulate the incidence of light on the retina. The aperture does exactly the same thing: depending on the set value, it lets more or less light into the lens or onto the sensor by enlarging or reducing the opening through which the light falls - like the pupil in the eye. When you look into a bright light, your pupil in the eye becomes smaller so that you are not too blinded by the light. In this case, the aperture is closed so that the photo is not overexposed, as too much light would reach the sensor through a large aperture.

You can also use the aperture to change the style of your recordings. In this section of the article, we will therefore go a step further and explain how you can use the bezel as a design element. An aperture of f8.0 is a good choice to start with.

An aperture of f8.0 is a good choice to start with.

Stand out foreground or background

You are probably familiar with these photos in which the foreground is sharp and the background is slightly or sometimes even very blurred. This effect is due to the choice of the aperture setting. Because the further you open the aperture, the more the focused foreground stands out from the background. However, this requires a small distance to the foreground. This effect is also referred to as the depth of field, which represents the extent of the sharp area in the image.

The indication of the aperture is usually misleading. Because a small aperture value like 2.8 or 4.0 means a wide open aperture and thus a lot of light falling on the sensor; a large value like 22 means the shutter is closed and very little light reaches the sensor. The reason is that the aperture values ​​are actually ratios. The value describes the ratio of focal length to aperture. A small value therefore reflects an open aperture, a large aperture value accordingly a small, closed aperture.

In the photo below, for example, we only focused the glass ball. We did not open the aperture completely so that the background does not disappear too much into a blur. Nevertheless, the sharp sphere stands out wonderfully from the background. Actually, the picture in the sphere was rotated by 180 °. This is due to the refraction of light in the sphere. We then rotated the content of the ball by 180 ° using image processing.


You can control the depth of field with the help of the aperture. For example, if you choose a smaller aperture, i.e. a large aperture value, your image will have an extended depth of field and the entire content will appear sharp from front to back.

Only things very close to the lens would be slightly out of focus.

If, on the other hand, you take photos with an open aperture, i.e. a small aperture value, your image has a narrowed depth of field. Depending on where your focus point is (i.e. the point on which you have focused your subject), the foreground or background in the image appears out of focus. As the aperture becomes smaller, the focus area increases, while it decreases as the aperture becomes larger.

With the help of the focal length you can control this effect of the depth of field even further. With a wide-angle lens you create a greater depth of field than with a telephoto lens with a longer focal length while maintaining the same distance to the object to be photographed. So if you want to build a specific blur into your picture, you can adjust this on your subject with the help of the aperture setting. It should be noted that choosing the right focus is essential. Depending on where you want to create your blur, you have to focus the foreground or the background. When the background is in focus, your foreground appears blurred, while when the foreground is in focus, the background appears blurred.

With the help of the aperture, you can influence other properties of your image in addition to the depth of field. In this way, the appearance and the effect of water surfaces and light sources on the viewer can be controlled or influenced with the screen.

Effect of water surfaces:

The effect of water can be influenced by the choice of different apertures in conjunction with the exposure time. With an aperture setting of 22 (closed aperture) and a long exposure time, the water looks rather hazy and washed out, but with an aperture setting of 4 and a short exposure time, it looks sharp and rich in detail. This is because with the shutter open you can capture a lot more light in less time. Waves or movements of the water are shown better here than on a photo, in which you have to expose longer through a closed aperture. Because the longer you expose, the more clearly you record the movements of the water. After a certain time, the water in your recording no longer looks sharp and detailed.

This comes about because an open aperture, as already described, lets more light onto the sensor and the image can therefore be exposed for a shorter time; a closed aperture lets in little light and the picture has to be exposed longer. The rapidly moving water then appears blurred and washed out because it has been moving continuously during the exposure. This effect can be seen in the photo below. With a closed aperture we could expose longer. During the exposure time, the waves of a passing ship lapped around the many small stones. Since the stones were now and then in the water and now and then in the dry, the veil effect was created.


The blurred display is often suitable for fountains, but for rivers or lakes the water that is too soft can quickly look unnatural. The example above shows that the water of a river can also be exposed for longer. The effect of the water depends largely on the exposure time and the flow speed of the water.

Appearance of light sources:

Furthermore, with the right aperture and exposure time, you can also influence the display of lights on your photo. With an aperture setting of 4 and a short exposure time, the light sources and their immediate surroundings appear slightly washed out, the radiation of the light is uniform.

However, if you choose an aperture setting of 22 and a long exposure, rays form around the light sources that look like stars in the end. You determine how strong these so-called aperture rays appear in the image with the aperture setting and the length of the shutter speed. Depending on how your picture should look later, you can influence the appearance of these rays.

The photo below was taken with a closed aperture of f22.0. This means that the rays around all the lanterns are particularly clear. Clear rays have also formed around the bright green light of the traffic light in the right part of the picture. We have deliberately used this effect here to underline the winter mood even further.

Exposure: 30 seconds, ISO 100, aperture: f22.0, focal length: 45mm

But why do these rays arise around all light sources? If the diaphragm is wide open, it forms an almost circular opening in the lens; in this position the diaphragm rays appear only very slightly or not at all. However, if the diaphragm has a small opening, as is the case with a closed diaphragm, rays form around the light source due to the angular arrangement of the diaphragm blades, which causes this effect. The number of beams depends on the number of diaphragm blades in the lens. If the number of lamellas is even, it is the same, if the number of lamellas is odd, the "star" has twice as many rays. This effect does not occur with lenses which, due to their design, always have a circular aperture. But this is seldom the case.

So you can conjure up a star effect around all light sources without the help of additional filters. If you want to intensify this effect, so-called star filters, which can be screwed in front of the lens, help. They have very fine milled grooves on the glass, which ensure that light sources create very distinctive asterisks in the photo.

The interaction of ISO, aperture and shutter speed:

The following photo illustrates the interplay of ISO value, aperture and shutter speed. Because all three things had to fit exactly with this photo. In order to actually freeze the falling snow on the Brühlsche Terrasse in the photo, even though the surroundings were very dark, a lot of light had to reach the sensor in a very short moment. Because if the exposure time were longer than a fraction of a second, the fine snowflakes would already show motion blur. They would then no longer look punctiform, but would be recognizable as lines on the photo.

So that enough light reaches the sensor in a very short time, we set the ISO value to 3200 and opened the aperture to the maximum. With the Canon EF 70–200 mm f / 2.8L IS II USM  we used, this was f2.8. With these two settings, we were able to reduce the shutter speed to 1/128 seconds - just enough to capture the falling snow in a point on the photo.

Are you wondering why the image noise doesn't bother you at such a high ISO value? The answer is very simple: you hardly see any difference between the fine snow that falls further back in the subject and the image noise.


Such a photo is only possible if all three settings are set correctly. It therefore illustrates quite well how these factors interact and how you can consciously design your motif.

The good thing about digital photography is that you can easily feel your way around the right settings. This is exactly how we proceeded with this photo. If you notice that the exposure time is still too long despite the aperture being open, increase the ISO value further to reduce the shutter speed. This only works in manual mode of your camera. There you specify all the settings exactly and no automatic is used.

There is a nice donkey bridge to the right aperture. “Photos at night? Use aperture 8 "

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