What does the lens aperture mean?

Question 1: What is the significance of aperture in photography? 1, concept

Aperture is a device used to control the amount of light entering the photosensitive surface of the fuselage through the lens, usually in the lens. For the manufactured lens, the diameter of the lens cannot be changed at will, but the luminous flux of the lens can be controlled by adding a polygon or circular aperture grating with variable area inside the lens. This device is called an aperture.

2. Calculation method

The aperture size is expressed by f value.

Aperture f value = lens focal length/lens aperture diameter

As can be seen from the above formula, to achieve the same aperture f value, the aperture of a long focal length lens is larger than that of a short focal length lens.

3. Aperture function

(1) can adjust the amount of light entering the lens. When taking pictures, if the light is strong, you should narrow the aperture, if the light is dark, you should open the aperture. That is to say, the smaller the F value (other parameters remain unchanged), the more favorable it is for shooting at night. The adjusting ring on the rotating lens or the knob on the digital camera body is used to adjust the aperture size.

(2) Aperture is the most important factor to determine the depth of field, with large aperture (small aperture value), small depth of field, small aperture (large aperture value) and large depth of field!

Question 2: What do you mean by big aperture and small aperture? The larger the aperture, the more the feed, and the smaller the aperture, the less the incoming light. (f/3.5 is a large aperture and f22 is a small aperture) The smaller the aperture, the larger the aperture and the smaller the aperture! I hope to help your brother! This is another key word for your camera:

ISO and image quality

ISO is a word with high exposure. When we buy cookies in the supermarket, we may see that our company has passed the ISO900 1 quality system certification on the packaging. This ISO is the abbreviation of International Organization for Standards. The International Organization for Standardization (ISO) has formulated the standards for biscuit management and film production, so there are several films on the shelves, namely ISO100,200 and 400, which are films with different photosensitive speeds. ISO sensitivity is the sensitivity of CCD (or film) to light. If ISO 100 film is used, if the camera can correctly expose within 2 seconds, then under the same light conditions, it only takes 1 second to use ISO200 film and 0.5 second to use ISO400 film. In the digital age, there are ISO options in the main menu of digital cameras, such as 100, 200, 400 or 800, just like those on film. Depending on the model, from ISO50 to 25600, the higher the number, the more sensitive it is.

Fast food is popular for lunch and love, so we should do everything quickly. It is reasonable that we like high sensitivity. However, there is no free lunch. Although high ISO is fast, the image is rough and cannot stand fine magnification. Therefore, landscape photography needs the lowest sensitivity of the camera to get a fine picture. High ISO is usually used only as a last resort.

People can't help themselves in rivers and lakes, and sometimes they have to, so high ISO image quality is one of the most important indicators of digital cameras. In dark places, such as dark rooms and midnight streets, even if the aperture is opened to the maximum at ISO 100, the shutter speed needs 1/4 seconds or even slower to properly expose. At this time, it is impossible to stabilize the camera without a tripod, and the photo will be burnt when the hand is shaken; Even with a tripod, as long as the subject turns his head, the photo will be posted. Flash can save the emergency, but it will destroy the atmosphere at the scene and make people look unnatural. Moreover, the effective distance of the small flash in the camera will not exceed four meters, and people and scenery that are a little farther away can't be photographed. What's more, flashlights are not allowed in some places, such as museums and theaters. We have no choice but to improve the sensitivity of digital cameras to ISO800 or even 1600.

Small digital DC and digital SLR DSLR, which are also/kloc-0.0 million pixels, will not have much difference in resolution and image quality if they shoot at the lowest sensitivity (such as ISO 100 or 80), assuming the lens quality is the same. However, if the ISO is raised to 400 for shooting, the difference in image quality will be obvious. The image taken by DSLR is still relatively clean, which is not much different from that taken by ISO 100, while the image quality of DC is obviously degraded, with great noise, distorted color and lost details. If we continue to upgrade to ISO800, the image quality of small digital DC can only be described in four words, while the image quality of digital SLR is acceptable although it has declined. If it is further upgraded to ISO 1600, the image quality of most digital SLR will be greatly reduced, but it can still meet the needs of enlarging 10 inch photos. At this time, the picture quality of the small digital DC is poor, and it takes a brave heart to dare to watch it.

In the case of equal pixels, the larger the CCD area, the better the imaging quality of high ISO. That is to say, when the CCD area is fixed, adding more pixels inside will lead to the decline of image quality. Therefore, the current digital camera should not simply add a few million pixels to the 6.5438+million pixels, but should work hard to improve the quality of CCD. It is urgent to reduce the noise level of high sensitivity (high ISO) and increase the exposure latitude.

Travel photography 8 million pixels is enough. When choosing a digital camera, we should not only look at the pixel height, but also pay attention to the size of the camera CCD. It's 2008, and the resolution is enough. It's time to pay attention to the picture quality.

shutter

In those years when photography was just invented, it usually took several minutes to take a photo. Most cameras don't need a shutter. At the beginning of exposure, take off the lens cover, then look at the watch. After five minutes, cover it and the photo will be finished.

Later, the photographic speed of film became faster and faster (ISO became higher and higher), and the exposure time became one minute ... >; & gt

Question 3: What exactly does the aperture marked on the camera mean? F/3.5-5.6 means that the maximum aperture of the lens is not constant. When the camera is set to the maximum aperture, it will automatically change between 3.5 and 5.6 according to the focal length and light. For example, if f2.8 is marked on the lens, the aperture of the lens will remain unchanged. The camera is set to 2.8 aperture, no matter how the focal length environment changes, it will be fixed at 2.8!

Question 4: What does the aperture of SLR lens mean? The cheapest card machine also has an aperture.

I suggest buying a book about photography.

Because we have to simply explain the aperture, there will be dozens of terms you don't understand in the process of explanation.

Question 5: What do lens apertures F 1.2, F 1.4 and F 1.6 mean? Aperture f value = lens focal length/lens aperture diameter, and the aperture diameter is controlled by lens aperture blades. For example, for a 50mm lens, the aperture diameter is 4 1.7 mm at F 1.2, 35.7mm at F 1.4 and 3 mm at F 1.6. The larger the F value, the smaller the aperture diameter of the lens and the greater the depth of field of the photo.

Question 6: What does the size of the aperture mean? The brother upstairs is right. The larger the aperture, the more the feed, and the smaller the aperture, the less the incoming light. (f/3.5 is a large aperture and f22 is a small aperture) The smaller the aperture, the larger the aperture and the smaller the aperture! I hope to help your brother! This is another key word for your camera:

ISO and image quality

ISO is a word with high exposure. When we buy cookies in the supermarket, we may see that our company has passed the ISO900 1 quality system certification on the packaging. This ISO is the abbreviation of International Organization for Standards. The International Organization for Standardization (ISO) has formulated the standards for biscuit management and film production, so there are several films on the shelves, namely ISO100,200 and 400, which are films with different photosensitive speeds. ISO sensitivity is the sensitivity of CCD (or film) to light. If ISO 100 film is used, if the camera can correctly expose within 2 seconds, then under the same light conditions, it only takes 1 second to use ISO200 film and 0.5 second to use ISO400 film. In the digital age, there are ISO options in the main menu of digital cameras, such as 100, 200, 400 or 800, just like those on film. Depending on the model, from ISO50 to 25600, the higher the number, the more sensitive it is.

Fast food is popular for lunch and love, so we should do everything quickly. It is reasonable that we like high sensitivity. However, there is no free lunch. Although high ISO is fast, the image is rough and cannot stand fine magnification. Therefore, landscape photography needs the lowest sensitivity of the camera to get a fine picture. High ISO is usually used only as a last resort.

People can't help themselves in rivers and lakes, and sometimes they have to, so high ISO image quality is one of the most important indicators of digital cameras. In dark places, such as dark rooms and midnight streets, even if the aperture is opened to the maximum at ISO 100, the shutter speed needs 1/4 seconds or even slower to properly expose. At this time, it is impossible to stabilize the camera without a tripod, and the photo will be burnt when the hand is shaken; Even with a tripod, as long as the subject turns his head, the photo will be posted. Flash can save the emergency, but it will destroy the atmosphere at the scene and make people look unnatural. Moreover, the effective distance of the small flash in the camera will not exceed four meters, and people and scenery that are a little farther away can't be photographed. What's more, flashlights are not allowed in some places, such as museums and theaters. We have no choice but to improve the sensitivity of digital cameras to ISO800 or even 1600.

Small digital DC and digital SLR DSLR, which are also/kloc-0.0 million pixels, will not have much difference in resolution and image quality if they shoot at the lowest sensitivity (such as ISO 100 or 80), assuming the lens quality is the same. However, if the ISO is raised to 400 for shooting, the difference in image quality will be obvious. The image taken by DSLR is still relatively clean, which is not much different from that taken by ISO 100, while the image quality of DC is obviously degraded, with great noise, distorted color and lost details. If we continue to upgrade to ISO800, the image quality of small digital DC can only be described in four words, while the image quality of digital SLR is acceptable although it has declined. If it is further upgraded to ISO 1600, the image quality of most digital SLR will be greatly reduced, but it can still meet the needs of enlarging 10 inch photos. At this time, the picture quality of the small digital DC is poor, and it takes a brave heart to dare to watch it.

In the case of equal pixels, the larger the CCD area, the better the imaging quality of high ISO. That is to say, when the CCD area is fixed, adding more pixels inside will lead to the decline of image quality. Therefore, the current digital camera should not simply add a few million pixels to the 6.5438+million pixels, but should work hard to improve the quality of CCD. It is urgent to reduce the noise level of high sensitivity (high ISO) and increase the exposure latitude.

Travel photography 8 million pixels is enough. When choosing a digital camera, we should not only look at the pixel height, but also pay attention to the size of the camera CCD. It's 2008, and the resolution is enough. It's time to pay attention to the picture quality.

shutter

In those years when photography was just invented, it usually took several minutes to take a photo. Most cameras don't need a shutter. At the beginning of exposure, take off the lens cover, then look at the watch. After five minutes, cover it and the photo will be finished.

Later, the photographic speed of film became faster and faster (ISO became higher and higher) ... > >

Question 7: What does a lens with a constant aperture mean? It is an advantage to ensure that the lens can shoot at a constant large aperture at each focal segment to obtain sufficient shutter speed. Of course, in aperture priority and manual mode, the aperture value can be changed completely. Many such lenses, such as Longteng 17-50, constant maximum aperture 2.8, Canon 50- 1.8, 50- 1.4, are all constant large apertures.

Question 8: What does the aperture of a digital camera mean? What happened? Aperture is a device used to control the amount of light entering the photosensitive surface of the fuselage through the lens. Usually in the camera. We use the f value to represent the aperture size. It is inversely proportional to the actual size, and the smaller the f value, the larger the aperture. The relative aperture of the aperture can also be called power, that is, the ability of the lens to allow light to enter. Refers to the light hole on the lens. The larger the aperture, the more light enters and the shorter the exposure time. Camera shake has little effect on definition. Even in the case of weak light, the lens with large light control can shoot (for example, f 1.2,1.4,2. , 2.

Aperture f value = focal length of Sichuan head/aperture diameter of lens

As can be seen from the above formula, to achieve the same aperture f value, the aperture of a long focal length lens is larger than that of a short focal length lens.

. The complete series of aperture values is as follows:

f 1，f 1 .4，f2，f2 .8，f4，f5 .6，f8，f 1 1，f 16，f22，f32，f44，f64

It is worth mentioning here that the smaller the f value of the aperture, the more light enters in the same unit time, and the light entering amount of the upper level is exactly twice that of the lower level. For example, if the aperture is adjusted from f8 to f5.6, the amount of light entering will double. We also said that the aperture should be opened one level. For consumer digital cameras, the aperture f value is often between f2.8-f 16. The aperture size has a great influence on the required lens diameter. When the focal length is long, the optical path is long and the loss is large. In order to make the same light reach the photosensitive layer, the diameter of the light hole must be increased accordingly. The basic formula is: under the condition of constant focal strength (aperture), the focal length must be doubled and the lens diameter must be doubled. If the lens diameter of the 50mm focal length lens F2.8 is 40mm, if the focal length of 100mm is to reach F2.8, the lens needs to reach 80mm, and if it is 200mm, the lens needs to reach160 mm. That's what the fixed-focus lens does. Because of its large volume, high cost and complicated technology. It is not conducive to promotion. Therefore, scientists have created a "floating aperture lens" at the expense of the amount of light entering, that is, the aperture automatically shrinks with the increase of focal length. Our little DC basically uses this lens. Of course, the quality is not as good as SLR fixed-focus lens or constant large aperture zoom lens.

Question 9: What does the numerical value on the lens aperture mean? The number of feet is feet.

Chicken is rice.

Numbers represent the distance from the object to the focal plane.

You can see the focal plane icon on the fuselage, which is a horizontal φ.