How does the camera calculate the depth of field

What is the depth of field of the camera?

The depth of field refers to the distance range that an object measured along the axis of the imaging depth of field machine can obtain a clear image in front of the camera lens or other imagers.

When the lens of a camera is clearly focused on an object, all points on the same plane perpendicular to the lens axis can form a clear image on the film. The distance between all the scenes before and after this plane is called the depth of field of the camera.

Extended data

Three elements of camera depth of field:

1, camera aperture

The relationship between aperture and depth of field is that aperture is large, depth of field is small, aperture is small and depth of field is large. When we shoot static images such as flowers, trees or people, we often choose a small depth of field, which can better express the subject, and a large depth of field is often used to shoot landscapes.

2. Lens focal length

Its relationship with depth of field is long focal length, small depth of field, short focal length and large depth of field. When using short focal length, the background blur will have obvious effect, which is suitable for shooting majestic mountains and vast grasslands; The long focal length is suitable for shooting portraits, which is convenient for blurring the messy background.

3. The distance of the subject

Refers to the distance between the lens and the subject. The depth of field can be changed by changing the distance of the subject. The subject near the lens has a small depth of field, while the subject far away from the lens has a large depth of field.

Hyperfocal distance: When the lens is focused to infinity, the distance h from the camera to the nearest clear object surface is called hyperfocal distance.

Hyperfocal distance is not a fixed value:

The larger the aperture opening, the greater the hyperfocal distance;

The longer the focal length of the lens, the greater the hyperfocal distance;

The larger the hyperfocal distance, the smaller the depth of field.

When the focus is at infinity, the boundary between the foreground depth and the camera is hyperfocal distance, and then the depth of field will not work. When the focus moves to the front limit of the depth of field, the farthest clear point is still at infinity, while the nearest clear point is closer to the lens. At this time, the distance from the nearest clear point to the lens is exactly 1/2 hyperfocal distance, and the depth of field is increased to 1/2 hyperfocal distance.

Calculation formula of depth of field:

Depth of field = (2 * circle diameter * square of lens focal length * aperture value * square of focal length)/(square of D circle diameter of lens focal length * square of aperture value * square of focal length)

As can be seen from the formula, the back depth of field

The prospect is far-reaching.

What do depth of field and aperture, wide-angle lens and telephoto lens mean respectively?

Depth of field refers to the spatial distance that can be clearly imaged. For example, when shooting people with shallow depth of field, the background of the people is blurred. The shallower the depth of field, the smaller the clear range. If you take a portrait with a large depth of field, the background will be very clear. Depth of field is closely related to aperture and focal length. At the same focal length, the larger the aperture, the shallower the depth of field, and the more blurred the Jiao Wai, and vice versa. Under an aperture, the longer the focal length, the shallower the depth of field. But for most pan/tilt with non-constant aperture, the change of focal length may affect the aperture value (for example, for a18-105mmf3.5-5.6 VR lens, the aperture can be opened to f3.5 at the wide-angle end of 18mm, but only to 5 at the telephoto end of105 mm). For a lens such as 24-70mmf2.8, a large aperture such as f2.8 can maintain the full focal length of 24mm-70mm, so it is very expensive).

The simple understanding of aperture is transmittance, which is expressed by f+ number. The aperture series of f 1.4, f 1.8, f2.0, f8 and f22 are getting smaller and smaller. Small aperture is generally used for landscape shooting with large depth of field, or shooting with extended exposure time (such as shooting water).

Wide-angle lens can shoot a wider range, mainly used for landscape shooting. The telephoto lens can shoot people and things farther away, and the composition can compress the space, which is suitable for shooting people and capturing distant scenery. Telefocus with a size of 300mm or more is rarely used by ordinary fans.

How to calculate depth of field and its concept

What is depth of field?

A: In principle, there is an allowable diffusion circle before and after the far focus and the near focus, and the range between them is called the depth of field. That is to say, before and after focusing, the image still has a clear range, and the depth of the subject before and after controls the blur degree of the image on the photosensitive element. The distance between aperture, lens and subject is an important factor affecting the depth of field. The larger the aperture, the smaller the depth of field, and the smaller the aperture, the greater the depth of field. The longer the focal length of the lens, the smaller the depth of field, and vice versa. The closer the subject is, the smaller the depth of field is, and the farther the subject is, the greater the depth of field is. In order to highlight the subject, many people will choose a small depth of field. Of course, if you want to shoot the scenery, we would recommend choosing a large depth of field.

Does the depth of field of the camera matter?

Is the depth of field to achieve clear subject and other blurred effects? SLR cameras are much more expensive than ordinary cameras. If the depth of field effect is achieved through post-production, wouldn't it cost less and have the same effect?

Answer: The depth of field is the clear range of depth of field when shooting. The depth of field is short when the aperture is large, and all SLR cameras currently on sale can basically achieve a better shallow depth of field. In addition, the depth of field is mainly the technical standard to measure the lens, not the absolute standard to measure the art of photography. Post-production photos can't get that absolutely natural effect.

Depth of field calculation formula

The depth of field calculation formula can help you understand the depth of field range of various lenses, various apertures and various lenses. This formula is aimed at the fuzzy circle you require, so the calculated depth of field range is more accurate and reliable. Of course, this is much more troublesome than Jing Shenbiao in the camera and Jing Shenbiao in the book.

The depth of field calculation formula is as follows:

Height × depth

Depth of field near the limit = ————

H+D-F

Height × depth

The far-reaching boundary of the scenery = ————

H-D-F

H = hyperfocal distance d = focal length (distance from the front node of the lens to the object) f

= lens focal length

For more information, refer to or calculate the hyperfocal distance in Section 4.

Let's take an example to illustrate the calculation of this formula: For a 50mm(0.05 m) lens, the hyperfocal distance distance of f8 is 6.25 m (the blur circle standard is 0.05mm), and when focusing for 4 m, the depth of field of f8 is as follows:

Height × depth

6.25×4

25

Depth of field near the limit =——————— = = 2.45 (m)

H+D-F

6.25+4-0.05

10.2

Height × depth

6.25×4

25

The far boundary of the scenery = ———————————————— = —— = —— =11.36 (m)

H-D-F

6.25-4-0.05

2.2

Therefore, the depth of field in this example is 2.45- 1 1.36 meters.

Who can tell me the conversion formula of depth of field?

Let me explain to the first floor what depth of field is-depth of field refers to the distance range that an object can obtain a clear image along the axis of the imaging depth of field machine in front of the camera lens or other imagers.

The following is the formula for calculating the depth of field. Where: Δ-dispersion allowable circle diameter f- focal length f- shooting aperture value l- focusing distance Δ l1-foreground depth Δ l2-back depth of field Δ l1= f Δ l 2/(f 2+f Δ l) (65438)

Back depth of field Δ L2 = fΔ L2/(F2-fΔ L) (2)

Depth of field δ l = δ l1+δ L2 = (2f2fδ L2)/(F4-F2 δ 2L2)

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What does depth of field mean?

"Depth of field" refers to the distance range of objects measured along the axis of the imager in front of the camera lens or other imagers, so that a clear image can be obtained.

depth of field

Depth of field is closely related to aperture size, lens focal length and scene distance. Good depth of field can be obtained by using small aperture, short focal length and proper shadow.

example sentence

Watch the viewfinder, colleagues. Please press the automatic exposure lock button in the preview bar.

For great photography, what matters is the depth of emotion, not the depth of field.

Flowers bloom and butterflies dance and the phoenix flies. The lotus fragrance in Shui Yang has a depth of field, the cold smoke is light, the ink is dyed, the light green is covered with glory, and another spring is melancholy.

Xue Rui is full of doors, and the idle sun shines on the depth of field. In a blink of an eye, it's time to change the year, thinking about the old things around the furnace. Pour a glass of wine with a smile and you can hear the fragrance from a distance.

I wish you all the best in the coming year. I wish you good health and all the best.

Mysterious white and floating blue snow powder constitute the depth of field.

When the depth of field effect is used on the grid, it can help to eliminate the ambiguity of the grid direction in the view.