In photography, every image tells a story. Sometimes it's an intimate portrait, where every
detail of a loved one's face is etched in sharp focus. Other times, it's a breathtaking landscape,
where everything from the immense sky to the tiny wildflowers blends into a visual harmony.
But how can a photographer control what's in focus and what's out of focus? How do they
juggle light to bring their vision to life?
The first essential parameter to consider is depth of field, which plays a fundamental
role in the way a photograph is perceived.
Every photograph has a focal point, but also a sharp area in front of and behind it, called the
depth of field. Sharpness varies according to aperture and distance from the subject. By
adjusting the camera settings, you can choose what is sharp or out of focus.
The concept of depth of field has been used since the earliest days of photography, but it was
Ansel Adams, a twentieth-century American photographer and environmentalist, who did
much to theorise and exploit it artistically. Adams is best known for his black-and-white
photographs of the landscapes of the American West, particularly Yosemite National Park.
In collaboration with Fred Archer, Adams developed what is known as the “Zone System”, a
method of controlling exposure and depth of field with great precision. The Zone System
relies on the understanding and manipulation of light to achieve a perfect balance between the
dark and light areas of an image. Using this approach, Adams was able to create photographs
with an impressive depth of field, where every detail, from the foreground to the background,
was in perfect focus.
Deep depth of field is defined by images that are sharp from start to finish. In contrast,in
landscape photography, where you often want to show all the nuances of a scene, deep depth
of field is frequently used. On the other hand, shallow depth of field refers to the fact that
some photographs have relatively small areas of focus.
Typically, photographs with a shallow depth of field are easily identifiable because the subject remains in focus, while the background is transformed into a smooth, creamy blur.
To create a depth of field that is as deep or as narrow as you like, you need to understand the
F variable and how it works. The f-numbers with the lowest values correspond to the widest
apertures, which means they create the shallowest depth of field. whereas the highest
f-numbers correspond to the smallest apertures, thus giving the greatest depth of field.
A larger aperture means a shallower depth of field. So, for a landscape, choose f/11 or higher
for a sharp transition between foreground and background.
On the other hand, for a portrait with a blurred background, set the aperture to f/2.8. In addition, the focal length is the distance between your lens and your subject.
It's important to note that depth of field is affected by aperture, distance to subject and focal length. Together, these elements can combine for a pronounced effect or,on the contrary, cancel each other out.
The second fundamental parameter to take into account is exposure, which directly influences the quality of the photograph. A well-mastered exposure results in images that are balanced in terms of brightness, guaranteeing optimal visual rendering.
Exposure is one of the fundamental concepts in photography. When you take a photo, you
press the shutter release to open the camera's shutter, and the light to which the sensor is
exposed triggers a response from the sensor.
Exposure is the amount of light that reaches your camera's sensor, generating visual data over a variable period of time, from fractions of a second to several hours.
To control exposure on a camera, you need to take into account three different data
parameters forming the exposure triangle: shutter speed, aperture and ISO sensitivity.
Shutter speed is the length of time the shutter remains open, measured in fractions of a
second.
In daylight, it generally varies between 1/1000 and 1/200 s. In low-light conditions,
you should prefer a slow shutter speed, and adjust your camera settings accordingly. In long
exposure, the shutter can remain open for several minutes to capture bright images.
On the other hand, to freeze a fast-moving action, it's essential to opt for a high shutter speed such as 1/400 s or more.
Next, let's move on to the diaphragm opening, which regulates the amount of light entering
the camera. This process is similar to that of the eye's iris. The smaller the f-number of the
aperture, the larger the lens opening.
A food photographer will choose a large aperture to highlight his subject and blur the background. Conversely, a small aperture will be used in landscape photography to achieve sharpness on all elements of the image, from nearby trees to distant mountains.
Before concluding, it’s essential not to confuse depth of field and aperture, because
although they are interconnected, they represent different concepts in photography.
The diaphragm opening refers to the size of the aperture in the lens, determining the amount of
light that reaches the sensor, and is measured in f-stops for example, f/2.8 or f/16. Depth of
field, on the other hand, refers to the zone of sharpness in an image, that is to say the distance
at which objects appear clearly in focus.
A large aperture “small f-stop” creates a shallowerdepth of field, highlighting the main subject with a blurred background, while a smallaperture “large f-stop”increases depth of field, bringing more elements of the scene into sharp focus.
In short, the diaphragm opening controls light, while depth of field influences the perception of sharpness in the image; these two elements, although closely linked, play distinct roles in photographic creation.