Welcome. In this article, I’ll talk about focus and how it relates to the title of our article. Depth of field in photography is an in-depth aspect for analysis. We often cannot give an exact answer to the question: “What do we focus our attention on when viewing the works of famous photographers?” The answer lies in the title of the article.
Depth of Field: What is It and Why is It Needed?
Probably, most photographers noted that the focus is focused on a certain area of the frame and that area that was not included in this area was out of focus, that is, blurred.
Depth of field (DOF) is the area of a photograph in which all objects are sharp.
Note that it is impossible to accurately figure out the clear boundaries of the depth of field. Sharpness is gradually replaced by its absence. Therefore, you should know the concept of “circle of confusion”, which means the very lack of sharpness in the image.
Why is this parameter necessary, because the photo must be clearly traced with all its details, because then its quality will be high? This is a statement by misguided novice photographers. I am often asked this question and I always manage to convince the interlocutor of the opposite.
Imagine that you are photographing a flower on a windowsill, and a car passing by accidentally gets into the frame. And then the gaze diverges: either looking at a flower, or at a car, and the viewer will be involuntarily repelled by this picture. They will say that he is unprofessional, since there is no single object that draws the whole gaze only at himself.
So, we came to the conclusion. To concentrate all attention on only one subject, they use depth of field, which helps to make a certain area of space in focus, and unnecessary objects of the picture are out of focus.
Factors Affecting This Shooting Parameter
What does depth of field depend on? Consider the factors:
Diaphragm. There is an interdependence: the smaller the lens aperture we make, that is, we set the aperture value higher, the greater the DOF. This parameter is the most convenient way to influence the depth of field, since it does not produce any distortion.
The focal length of the lens. Higher focal lengths are associated with a shallower depth of field.
Focusing distance. The greater the distance to the subject being shot, the less DOF will be.
Permission. The higher the pixels on the camera monitor, the more visible small areas of blur are. Decreasing the resolution will increase the depth.
Depth of Field: Calculation Formula
There is a certain formula with which we will calculate the depth of field, knowing the necessary values of the main factors on which the depth depends.
R1 = (R * f²) / f² + K (R – f) * z
R2 = (R * f²) / f² – K (R – f) * z
I will write down what letter means:
- R1 – front edge of DOF;
- R2 – edge of the end of the depth of field;
- R – focus area;
- f is the focal length of the lens;
- K is the aperture value;
- Z is the diameter of the scattering circle.
How to Calculate the Distance in The Image?
It is necessary to subtract R2 from the value of R1.
Let me remind you that when measuring the focusing distance, the boundaries are measured from the focal plane, which is indicated on your camera.
This formula is rarely used manually, since there are a number of programs in the form of calculators, which, when entering parameter values, calculates the required depth of field for you. Well, nevertheless, it was worth considering it, it might come in handy someday.
When Do You Need to Accurately Calculate Depth of Field?
Mainly for those photographers who print their work on large paper sizes. Of course, there are some peculiarities when shooting in different genres.
When shouldn’t You Calculate?
If you are an amateur and mainly print pictures on a small standard format 10×15 cm, then you don’t need it at all.
What other photo formats are there?
Art photography, where sharpness does not play a decisive role.
Each lens has its own depth of field scale. Let’s consider the cases of its application:
- Emphasizing the compositionally important aspect of photography from a large number of objects.
- Determining the boundaries of the depth of field.
Artistic Application of Depth of Field
You should always cover the aperture when shooting a multi-faceted composition. But we will consider in which specific genres this is manifested:
When we photograph nature, we want all the details to be clearly traced, that is, all the plans. Therefore, professionals make the aperture more closed, that is, they expose a larger aperture value: from 8 to 16.
There is an exception: if the shooting is taken without a close foreground, then the aperture is not closed too much, since all landscapes are located at the same level relative to the photographer.
If you are shooting for catalogs, then a mandatory requirement is to get the whole subject into focus.
If you are photographing for yourself and with a creative intention, then the depth of field is exposed at your discretion.
It is carried out at short distances, so in order for a flower, insect or a drop of water on a leaf to be in focus, the diaphragm must have a small opening.
Some lenses allow you to set f/32, but generally the values range from 16 to 22.
Closed Aperture Tips
Experts advise against setting low aperture values, that is, setting values higher than f/12, as detail begins to decrease and distortions appear – diffraction. Professionals break this rule only when shooting macro. But they never reach the threshold of the diaphragm.
The smaller the aperture number, the smaller the “pupil” of the lens, which means there is a lack of light. To compensate for the lost light, you need to increase the shutter speed. You can raise the ISO, but then noise awaits you, so I personally recommend using a slow shutter speed and a tripod.
When we want to highlight the main subject of the shooting, and blur the background, that is, emphasize the subject with focus, then we use an open aperture.
Love for Bokeh
Shoot anything with a blurred background and get interesting beautiful circles out of focus.
How to Blur the Background?
A blurred background, or if we call it “bokeh” in professional language, is a consequence of a small depth of field.
To get a creative background, high-aperture optics with a long focal length are used, usually over 35 mm. It can be both telephoto lenses and portrait lenses.
Here are some examples of Nikon’s top lenses:
You can often hear the term infinite depth, that is, an area in focus to the horizon. The hyperfocal distance is a point oriented for us, beyond which the sharpness decreases towards the horizon. The values are calculated from the depth-of-field photographer tables. At the same time, the data of those factors on which the depth of field depends are entered into the table.
Remember that the artistic idea is higher than the quality of the photo. Therefore, look for unusual subjects, take pictures, and the depth of field will help to raise the technical quality of the photo.
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