Q&A on aperture knowledge (who can popularize the knowledge of aperture and shutter of camera lens)

1. Who can popularize the knowledge of camera lens aperture and shutter?

The aperture controls the amount of light entering the lens, and the shutter (speed) controls the exposure time. The exposure of a photo is determined by the aperture and shutter speed. They set all the gears on the phase machine in descending order according to the multiple relationship of 1/2. For example, the aperture 1.4, 2, 2.8, 4, 5.6, 8. ... =' class1' > decrease the optical input of 1/2, and the shutter 1/4, 1/8, 115, 1/30,1... The choice of aperture and shutter is not unique for correctly exposed photos. If the aperture is increased by one step and the speed is decreased by one step, the exposure will not change.

Because the aperture has the function of controlling the depth of field (that is, the aperture is large and the depth of field is small, and the aperture is small and the depth of field is large), the shutter has the function of controlling the exposure speed. Therefore, when using automatic exposure in photo creation, if there is a requirement for depth of field, aperture is preferred. After setting the aperture to meet the depth of field requirements, the shutter speed is automatically selected by the camera, which is called aperture priority. If there is a requirement for speed (such as sports photography), choosing shutter is preferred. After setting the shutter speed, the aperture is automatically selected by the camera, which is called shutter priority.

2. Problems with shutter and aperture device.

1, shutter position: door b, 30s, 15s, 8s, 4s, 2s, 1s, 1/2s, 1/4s, 1/5s,/kloc. 1/250, 1/500,11000, 1/2000, 1/4000, 1/8000 and so on

2. Please look at answer 3 first. Other things being equal, the shutter is raised by one level and the luminous flux is halved.

Other things being equal, if the aperture value is one step ahead (that is, the aperture is reduced), the luminous flux will be halved. It can be seen that when other conditions remain unchanged, when the exposure is correct, the shutter is raised by one step and the aperture value is lowered by one step (that is, the aperture is enlarged) to ensure correct exposure.

For example, in the same environment, F2.8,11000s is correctly exposed. Now, if you want to reduce the aperture to F4, the light input will be halved. If you want to expose correctly, you have to slow down the shutter speed and increase the light input to1/500 s. 3. The relationship between two adjacent aperture stops is that the light input is doubled, that is, the light input of the former, such as F2, is twice that of the latter, F2.8.

4.ISO is related to shutter and aperture. Every time the sensitivity is doubled, the sensitivity of the photosensitive element to light will be doubled, and the shutter speed will be doubled or the aperture will be reduced by one step.

For example, in the same environment, ISO 100, F4, 1/30s is the correct exposure. Now I have raised the ISO value to 200 and doubled the sensitivity. If I want to expose correctly, in the first case, under the condition of constant aperture, the corresponding shutter speed will be accelerated to reduce the amount of light entering, so I will adjust it to 1/60s. In case 2, if the shutter is unchanged, the corresponding aperture will be reduced by one step, that is, the aperture value will be increased by one step to reduce the amount of light entering, so it should be adjusted to F5.6

If you feel dizzy, make sure the light is clear. The larger the aperture (the smaller the aperture value), the more light will enter.

The faster the shutter speed, the smaller the light input, which is inevitable; The slower you are, the more light you get. Both of them are easy to understand, aren't they? The higher the ISO value, the more sensitive it is to light, which can be roughly understood as an increase in the amount of light entering.

Although this understanding is not accurate, it is a simple way to remember the relationship between values.

3. Photography common sense parameters of aperture and shutter combination

The combination of aperture and shutter has little to do with the weather, but the combination of exposure has something to do with what you want to express. The simplest example is that portraits are usually shot with a large aperture, which can not only highlight people with a small depth of field, but also capture portraits with a high-speed shutter to prevent the picture from blurring. Shooting a scene requires a small aperture to obtain a greater depth of field and make the whole picture clear and sharp.

You can also try 4 seconds exposure, 1/500 seconds exposure to capture the effect of water flow.

Tell you a common exposure combination: sunny day 16 rule. When shooting a positive object on a sunny day, the aperture is selected at F 16, and the shutter is the reciprocal of the camera ISO (if the ISO is 200, the shutter is 1/200 seconds).

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