Introduction to Photographic Notes _ Aperture, Depth of Field and Focus

Aperture is the most influential parameter in photography. From the perspective of exposure, the aperture reflects the amount of light entering. In addition, the aperture will also affect the depth of the photo and the Jiao Wai blur effect of the photo.

Depth of field is the range of clear images before and after focusing, which can be understood as the range of clear images in photos. Understanding depth of field is the premise of understanding focusing. The so-called focusing is to focus on the subject so that the subject is within the depth of field. In fact, this is to make the subject in the photo clearer.

The deeper the depth of field, the greater the clear range of the photo; The shallower the depth of field, the smaller the clear range of the photo.

The following is a schematic diagram of depth of field.

Generally speaking, the factors that affect the depth of field are the frame of the sensor (this is determined by the camera body model), aperture, lens focal length and shooting distance.

When the frame of the camera sensor is the same, the focal length and shooting distance are the same for an image with a depth of field of 4 times the aperture. That is to say, under the same shooting distance, the depth of field effect of 25mm f/2.0 aperture photos is the same as that of 50mm f\8.0 photos.

Depth of field refers to the clear and unclear range of photos; Blur refers to the blurred part of a photo. Generally speaking, the depth of the scene has a good blurring effect. However, the two are not completely equivalent.

The depth of field reflects the range of clear objects in photos, but the blur ability contains many contents, including Jiao Wai blur ability, Jiao Wai blur effect, suburban aperture shape and so on.

Generally speaking, blur effect has more to do with aperture. The larger the aperture, the more pages, and the better the blur effect. At the same time, the larger the aperture, the shallower the depth of field, and the better the blur effect.

Different subjects have different requirements for depth of field.

Focusing is to keep the subject within the depth of field.

The normal focusing operation is as follows: first, select the focusing mode, select the focusing mode, focus on the subject, and the camera will focus automatically by half pressing the shutter. After focusing successfully, press the shutter to finish shooting.

(1) One shot

Single autofocus is the function of camera manual autofocus, and the camera only focuses once. After focusing, the camera temporarily stops moving, so that the focusing position is temporarily fixed, which is suitable for shooting subjects with less movement. Such as portraits and landscapes.

(2) artificial intelligence servo autofocus (AI SERVO)

Artificial intelligence servo autofocus is an autofocus mode, and the camera automatically focuses continuously until the shutter button is pressed. It is suitable for shooting moving objects and can automatically track the objects approaching at high speed. Such as sports and animals.

(3) artificial intelligence focus

In the artificial intelligence autofocus mode, you can automatically switch between single autofocus and artificial intelligence servo focusing according to the action of the subject. Therefore, this mode is suitable for shooting subjects whose actions are unpredictable. Such as snapshots, children.

Common focusing methods are: single-point autofocus; Area autofocus; Global focus, etc. Even now, the new camera has facial autofocus and so on.

But in daily shooting, we usually use single-point autofocus and area focus, and only when shooting sports, we may use global focus.