What is photography?

Simply put, it refers to the process of recording images with some special equipment. Generally, we take pictures with mechanical cameras or digital cameras. Sometimes photography is also called photography, that is, the process of exposing the photosensitive medium by using the light reflected by the object. Someone once said an incisive language: the photographer's ability is to transform the fleeting ordinary things in daily life into immortal visual images. Photography is divided into the following categories: documentary photography, artistic photography, photo photography, holographic photography, painting photography, impressionist photography, realistic photography, naturalism photography, pure photography, neo-objectivism photography, surrealism photography, abstract photography, comparable photography, "Dadaism" photography and subjectivism photography.

Image depth

The distance between two imaging planes where the front boundary of depth of field and the back boundary of depth of field are conjugated respectively. Image depth corresponds to the depth of field, and the greater the image depth, the greater the depth of field.

Criteria for determining the depth of field: 135 The diameter of the blur circle allowed by the camera is generally 1/30 mm, that is, 0.033mm..

Hyperfocal distance:

When the lens is focused at infinity, the scene at infinity forms a clear image, and at the same time, the object at a certain point at a limited distance can reach a clear standard, and the object near this point is blurred, so the distance between this object and the lens is hyperfocal distance.

focal distance

The distance from the center of the lens to the focus. The unit of focal length is usually expressed in mm, and the focal length of the lens is usually marked in front of the lens, such as f=50mm (this is what we usually call "standard lens"), 28-70mm (our most commonly used lens), 70-2 10mm (telephoto lens) and so on.

hole

A device that controls the amount of light passing through a lens.

shutter

Device for controlling exposure time. Shutters can generally be divided into curtain shutters, lens shutters and steel shutters. Among them, curtain blinds can be divided into vertical curtain blinds and horizontal curtain blinds. Steel shutter can reach higher speed (the highest shutter speed can reach112000 seconds or more at present). Generally, the highest speed of the inter-mirror blade shutter does not exceed 1/500 seconds, but the biggest advantage of the inter-mirror blade shutter is that the noise generated during shooting is extremely low, which is very conducive to sneak shots and can realize synchronous flashing within the full speed range.

Shutter speed

Opening time of shutter. It refers to the time (exposure time) when light sweeps across the film. For example, "1/30" means that the exposure time is 1/30 seconds. Similarly, "1/60" means that the exposure time is1/60s, and the shutter of1/60s is1/30s. The rest and so on.

Note: Some materials refer to shutter speed as shutter time. The two names are different, but they mean the same thing, both referring to the shutter opening time.

depth of field

The relatively clear range of the image. The depth of field depends on three factors: the focal length of the lens, the distance between the camera and the subject, and the aperture used. The relationship between depth of field and the above three factors is: the longer the focal length, the shorter the depth of field; The shorter the focal length, the longer the depth of field (for example, under the same aperture and distance, the scene of 28mm lens is far greater than that of 70mm lens); (2) The closer the distance is, the shorter the depth of field is, and the farther the distance is, the longer the depth of field is (for example, under the same focal length and aperture, the subject scene at 10 m is far greater than the subject depth of field at 1 m); (3) The larger the aperture, the shorter the depth of field, and the smaller the aperture, the longer the depth of field (for example, under the same focal length and distance, the scene with the aperture of F 16 is far greater than the depth of field with the aperture of F4).