What is the function of aperture?

Aperture, called aperture in English, determines the amount of light passing through the lens aperture in unit time and is one of the most important indicators of camera lens. The functions of the aperture can be roughly divided into the following categories: controlling the exposure time, changing the depth of field of the image and affecting the sharpness of the photo. Let's look at the function of aperture.

What does the aperture do? 1 The function of the aperture: change the shutter speed. Generally speaking, the exposure of a camera at the same sensitivity is determined by the aperture size (aperture f value) and shutter speed. Aperture f value = lens focal length/lens aperture diameter, that is, the smaller the aperture f value, the larger the aperture, and the greater the light input. So you can increase the aperture to increase the shutter speed, or decrease the aperture to decrease the shutter speed.

Under the same photographic environment and sensitivity, shooting with large aperture (small F value) can effectively improve the shutter speed. Moreover, in many cases, shooting with a larger aperture will not have a greater negative impact on the image quality of the camera than improving the ISO sensitivity.

The function of aperture 1: blur the background

Aperture can change not only the shutter speed, but also the depth of field. First, let's understand the concept of depth of field.

Depth of field: There is a certain length of space in front of the lens (before and after focusing). When the subject is located in this space, its image on the negative is just between the two diffusion circles before and after focusing. The length of the space where the subject is located is called the depth of field. In other words, the blur of the image presented by the subject on the negative plane of this space is within the limited range of the allowable circle of dispersion, and the length of this space is the depth of field. Simply put, the shallower the depth of field, the more obvious the background blur, and the deeper the depth of field, the clearer the background.

How to set the aperture The screenshot on the left is the imaging screenshot of Olympus 300mm/F2.8 lens under various apertures. Under the same focal length, the larger the aperture, that is, the smaller the F value, the more obvious the blur effect of the background and the shallower the depth of field. Therefore, if you want to take a photo with a blurred background, try to use a large aperture at the same focal length.

The function of aperture 2: It affects the imaging quality of DC.

Theoretically, the size of the aperture has nothing to do with the sharpness of the camera's focused imaging, but because the imaging principle of the optical lens and the accuracy of glass refraction cannot be consistent with the theoretical value 100%, the imaging quality under different apertures is still different.

Compared with the optical lens of SLR camera, the aperture range of DC lens is much smaller, especially its minimum aperture value is generally F8.0.

At the same time, for the vast majority of DC, the maximum aperture (that is, the aperture with the smallest F value) is the aperture with the best focus definition, that is, the best aperture that everyone says, whether it is at the wide-angle end or the telephoto end of the camera. Through the above resolution values obtained in the laboratory and screenshots taken in real scenes. Therefore, when shooting with a small DC, try to shoot with a large aperture, except for photos that need a large depth of field such as scenery.

The function of aperture 3: SLR camera that affects the imaging quality.

Compared with consumer digital cameras, the lens of SLR cameras has a more complex optical lens structure and a larger optical lens, and different apertures generally have a greater impact on the focusing quality of SLR lenses. I will still explain it to you through laboratory shooting and live screenshots.

What is the function of aperture? 2 Aperture is generally represented by a numerical value, such as F2.8 and F8, which is formally written as f/2.8 and f/8.

This value is the quotient of the current focal length of the lens divided by the aperture, indicating that the larger the aperture, the larger the denominator and the smaller the aperture value. So remember that F2.8 is bigger than F8, F4 is bigger than F5.6, the smaller the number, the bigger the aperture, and the bigger the number, the smaller the aperture.

Generally speaking, an aperture larger than F2.8 is called a large aperture, and an aperture smaller than F8 is called a small aperture.

So what effect does aperture have on our shooting?

The main function of aperture

The aperture determines the light transmittance.

The larger the aperture (the smaller the numerical value), the larger the aperture, the more light passing through per unit time, and the stronger the light passing ability.

It can be said that the bigger the aperture, the brighter it is.

For shooting the starry sky, if you use high sense, the noise in the picture will be ugly and the picture quality will be too poor. If you don't want to use too high sensitivity, you can only start with the aperture shutter.

Because of the earth's rotation, there is a 500 principle for shooting the starry sky, which is to divide 500 by your equivalent focal length to get a number. In principle, if the shutter speed is slower than this number, there will be a star orbit.

Therefore, when shooting the starry sky, the aperture is larger and the picture will be much better. That's why when I recommend a super wide-angle zoom lens, I must ask the other party if they want to shoot the starry sky. If so, the aperture of F2.8 is the limit. It's not good to be smaller.

Aperture affects blur effect.

The larger the aperture and aperture, the stronger the background blur ability. Why is this happening? Teacher Ning won't talk to you about optical principles. Just remember that the principle of pinhole imaging is that the smaller the hole, the clearer it is. Conversely, the larger the aperture, the easier it is to blur.

Under the same conditions, the larger the aperture, the easier it is to blur.

The above picture shows the shooting effect of 85mmF 1.2 aperture.

The above picture shows the shooting effect of 85mmF 16 aperture.

So I want to make it very dreamy, and the combination of reality and reality is indispensable.

Other auxiliary functions

A small aperture can produce a canopy effect.

When a very small aperture is used, a star line will appear in the point light source in the picture. Generally, we can shoot with an aperture of about F 16.

A large aperture can make the foreground disappear.

When using a large aperture, if there is a prospect close to your camera, such as barbed wire, fences and other unavoidable things. You can use a large aperture, so the foreground will be blurred-until you can't see it.

Small aperture can check the cleanliness of the lens.

Is the lens dirty? You can take a photo against the white wall with a small aperture. A small aperture will make the dirt on or inside the lens more obvious. If it's not serious, we won't have to clean it up.

You can see the stain in the upper left corner of the picture above.

Large aperture can shoot different shapes of light spots.

The blurred shape of the light spot is often the shape of your aperture. If we open the aperture to the maximum, we can add a piece of cardboard in front of the lens and carve the shape we want in the middle of the cardboard-make sure it is smaller than the aperture at the maximum aperture. The hole in the cardboard becomes the real aperture, and the fuzzy light spot is the shape of the hole in the middle of the cardboard.

Aperture is basically that simple. Everyone should remember:

1, and the aperture is the ratio of the aperture size in the lens.

2. The larger the aperture, the smaller the value, and the smaller the aperture, the larger the value.

3. The bigger the aperture, the brighter it is, and the smaller the aperture, the darker it is.

4. The larger the aperture, the stronger the blur, and the smaller the aperture, the weaker the blur.

Sunset photography skills

Here, we have collected 6 photography skills, so that you can better capture those beautiful sunset scenes:

1. Shooting plan

On average, the sunset takes only 30 minutes a day. So it is very difficult to capture that wonderful moment at the right time, which means that you must have sufficient preparation and reasonable planning skills. When shooting, you must pay great attention to controlling your time, layout and position until you finish shooting. It is worth noting that your composition and framing concept will increase the unique perspective of your final photography effect. Sometimes, you may have just walked by the roadside and witnessed an unforgettable sunset. If you are ready and understand the complexity of photography, this situation is unexpected, so it is not enough to surprise you.

2. Preparation for shooting (equipment and accessories)

Shooting a sunset requires enough natural light to expose it, so camera shake is not a problem. However, the lens you choose has a great influence on your final photographic effect. A long focal length lens can give you a magnified view of the legendary sun. On the other hand, a broad perspective can give you unlimited carving space. If you are shooting a sunset-themed picture, in order to make up for the underexposure, you may use the artificial light reflected by the diffuse reflection surface to control the change of this extreme natural light, but in any case, try to avoid using the flash.

3. Mastering the exposure at sunset is the key to shooting a beautiful sunset.

Capturing the splendor of the sunset and its magical light is very tricky. Observing the sunset with an implicit golden tone, the underexposure is enough to lead to the failure of this photography. What the sunset needs is a slight exposure to maintain the layout of its low-light environment (otherwise it will look like an afternoon scene). This is because the photometry of the camera is different from that of the human eye. So when you shoot the sunset, you always use this technique: directly measure the space above the sun (there is no picture of the sun), and slow down the shutter speed through the aperture of 1f, which will delay the photographer's impression for half an hour. Follow this technique, and then get the right exposure, you can capture the perfect sunset photography effect.

4. Consider camera settings (and modes)

Tripod: Set the camera to stand mode and consider taking three photos with equal exposure (less than one level, normal and over one level).

Aperture priority mode: Choosing the aperture priority mode of the camera allows you to better adjust the size of the sunset when imaging. To fully understand this principle, you need optometry. In any case, a larger aperture can make your subject have a larger image. If you want to get starlight imaging effect, you may need to set a smaller aperture value, such as f/ 16 or less.

Save it in RAW format when shooting: it is difficult to control the time when shooting sunset, and you must try to get enough exposure. When you take a picture, you can save it in RAW format, which allows you to make a big exposure adjustment when processing the image, and even restore the shadow in some details. At the same time, it can better control various parameters, such as white balance, contrast, saturation and so on.

5. Photographic composition-Add your own understanding of sunset.

Photography course

Take your unique perspective as the core of photography art and run through the whole work of photography composition. Photographic composition is to increase readers' interest in pictures and finally attract readers' attention. When you shoot a sunset, try to recall and use one or more of the following creative techniques:

Trigonometry: Trigonometry is a part of the law of synthesis, and its appearance implies that the artistic theme (or other main elements in photographic composition) is placed in the third part of the frame structure. This placement can start from any direction of the frame. The setting sun will look clearer and more natural when placed in the lower part of the picture or in a photo frame. Plus some close-up shots (such as birds, trees, rocks, etc. You may need to arrange the sunset in the first third or the last third, so that both can appear in the picture at the same time, and the effect is very good. However, when you are shooting, it is not entirely about sunset, it may be similar to the reflection of the sun on the sea. In this case, the theme covers a wider range, so the spatial layout of its integration into photographic composition will be larger.

Golden section method: the theme picture is arranged in the middle or one third of the picture, and the golden section method is more attractive, and the picture is biased towards the middle position. Putting the theme in the middle may make those ugly pictures look hypocritical and mediocre. On the other hand, the use of the golden rule and trisection can often enhance the attractiveness of photos.

Try to use some other elements in the close-up: a single sunset doesn't look perfect. Adding some elements such as trees, hills, beach waves and so on to the close-up part will make your captured perspective more attractive.

Take the cloud as the background: Taking the cloud as the background will make the whole composition look more dramatic. At the same time, at the moment you shoot, the cloud may also destroy the whole picture you want. Looking for and capturing more attractive images usually refers to the sunset ... maybe a small silver edge or a cloud decorated with gold.

Natural framing: Adding natural framing pictures can integrate your creativity and imagination into the pictures you take, and then tell readers its own story through your pictures. If you are shooting a simple and calm sky, it may be more natural to shoot the sunset from the back of a tree or a certain angle of a rock to show its drama and the shooting concept centered on it. Although sometimes an extremely simple method such as shooting "The Sun on the Horizon" may overwhelm all the above languages.

Perfect shooting location: beaches and sunset spots (mountains and hills in the sunset) are considered as the first choice destinations for shooting sunsets. The combination of sunshine on the calm sea and golden sand beach (after the tide recedes) can be said to be the best composition. But it can only be compared with the sunset scenery taken from the perspective of wheat fields and flower decorative crops.

Silhouette: Silhouette is a very creative way to emphasize the "set" effect when shooting the sunset. It allows you to highlight the shooting effect of sunset through the hidden details of foreground elements/objects (elements hidden in shadows without any details).

6. Finishing (in order to restore the original image effect of sunset as much as possible)

In post-processing, retouching may only make your image look more professional. If you are a purist, you can skip this step directly. However, like everyone else, a perfect film needs a lot of work, including perfect post-production. If your image is raw data, then this step is essential. Proper adjustment of golden warm tone, white balance and tone will help the picture return to the original scene. Try to adjust this delicate balance, try to reduce the sense of falsehood, and keep the natural appearance and feeling of the sunset.

Looking back at the photographic sketch of the sunset scene in the above tips, it is incredible that it is so real. Please collect them and add them to your beautiful sunset album.