Such equipment is needed when shooting in low light conditions. For example, if you want to beautifully shoot a starry sky, a dark grotto or a cave. Photo: sway.office.com [ad_1]
What is lens aperture? This is a parameter that characterizes the transmission of light by an optical system (camera lens). It is necessary to pay attention to it when buying photographic equipment. In this material, we talked in detail about what lens aperture is and what it affects.
Such equipment is needed when shooting in low light conditions. For example, if you want to beautifully shoot a starry sky, a dark grotto or a cave. Photo: sway.office.comAbout optical aperture in simple words
What is luminosity measured in
Effective and geometric luminosity
What is a fast lens
When high camera aperture matters
Aperture and lens choice
About optical aperture in simple words
All lenses allow light to pass through the lenses. The amount of transmitted light depends on various parameters. For example, on the degree of transparency of the lenses.
But the main parameter that affects the beam of transmitted light is the degree of aperture opening. This is a plastic rotary disk, which consists of plates, “petals”. When turned, the petals open (a round hole appears between them) or close. The more the plates are opened, the more light they let in. The more the aperture of the lens can be opened, the higher its aperture ratio.
How to find out the aperture ratio of the lens, where to see the desired parameter? The value is written on the hardware itself. The number written on a particular model is the maximum. Aperture opens up to this value. Less is possible, more is not.
The smaller the number, the higher the value. For example, there are three lenses with different apertures: F4, F2.8, F1.2. The last one has the largest one (the diaphragm can open as much as possible), the first one has the lowest one. The second option is the average.
Aperture is not light sensitivity. The first is the characteristics of the lens. The second is ISO, a parameter that characterizes the level of sensitivity of the matrix (the detail that “turns” light into a picture) to light. This term refers to exposure. It has already been discussed in detail in the blog.
Aperture is a parameter that is not always constant. For example, there are lenses for which this value changes with different zooms. For example, NIKKOR Z DX 16–50mm f/3.5–6.3 VR. It was mentioned in one of the reviews.
The NIKKOR Z DX 16–50mm f/3.5–6.3 VR is a folding, compact wide-angle lens. Photo: millenniumoptiks.in
At the minimum focal length of this model, the indicator is F3.5 (maximum aperture), at the maximum it drops to F6.3. This feature is more common in budget equipment. For more expensive models, the indicator is unchanged. This means that they have the same aperture at any focal length.
What is luminosity measured in
The letter “F” is written next to the number on the equipment. This is the “F‑number”. It is determined by a simple formula: Divide the focal length of the lens by the aperture diameter. The result is the number we need. For example, the focal length is 50 mm. And the maximum opening is 25 mm. Divide 50 by 25. It turns out that the aperture ratio is 1: 2 (F2.0).
It is important to understand that the aperture is only a mechanism that reduces and increases the diameter of the hole (light enters through it). Its maximum size is limited by the design of the lens.
But the diaphragm may not be at all. In this case, the shooting always takes place at the “maximum open aperture”. It is this mechanism that is used in smartphones.
What is the difference between F32, F1.4 and F5.6 lenses and others? In the degree of aperture opening and in the amount of light transmitted. The available difference is shown in the picture below.
diaphragm row. Photo: assets.prophotos.ruWith a smaller aperture, there is more depth of field (the area in which objects are in focus), and less light enters the matrix.
If the aperture blades are wider open, the opposite happens. The depth of field decreases, and a larger beam of light enters the matrix.
What is the maximum aperture opening? Usually it is not more than 1. But there are fast models with F0.95 and more. How is this possible? Everything is simple. The focal length of the lens must be less than the hole diameter. As a result, when dividing a smaller number by a larger one, the result is less than 1. Examples of such models:
– Laowa 33mm f/0.95 Argus CF APO;
– Handevision IBELUX 40mm f/0.85;
– Handevision IBELUX 40mm f/0.85;
– Canon 65mm F/0.75;
– Carl Zeiss Planar f/0.7.
The Carl Zeiss Super Q Gigantar 40mm f/0.33 is a joke model that has never been photographed. Photo: cameralabs.orgEffective and geometric luminosity
Everything we talked about above refers to geometric parameters. Since the size, diameter is taken into account. But no lens transmits light 100%. For example, part of the light is reflected from the glass surface. The quality of lenses and anti-reflective coatings can affect this.
And if the lens is dirty, then light loss can reach up to 50%. Therefore, it is better not to forget to clean it from time to time.
Outcome: due to many factors (the quality of the lenses, the complexity of the design, etc.), the actual aperture ratio of the equipment will always be slightly less. How much? There is no universal indicator. It is necessary to conduct research on a specific lens.
If the geometric indicator indicated by the manufacturer is marked with the letter “F”, then the effective one is indicated with the letter “T”. You can find it on the websites of various laboratories that are engaged in such research. For example, DXOmark.
In the graph table with the desired parameter — Transmission. Photo: dxomark.comImportant: for lenses with the same “F”, but different “T”, the picture will be different. The brightest will be the one that is shot on the “T” with a large indicator. Sometimes it is very important. For example, when filming. That’s why cinema lenses are marked not “F”, but “T”.
What is a fast lens
This category includes options that have an indicator of F2.8 and above (F2, F1.4, etc.).
If we are talking about zoom lenses, then such models have the highest aperture value of F2.8. Equipment with this indicator is usually large in size and has fast autofocus.
There are also fast fixed lenses. They do not have the ability to change the viewing angle. But at the same time, they are usually small in size, allowing you to get a clear image even in dim light. Their aperture can be from F2 and above.
The fastest lenses can be used by owners of full-frame cameras. There are budget and expensive models from different manufacturers.
For medium format cameras (matrix larger than 36x24 mm) there are no such supermodels anymore. The maximum that manufacturers offer is F2.8. Why is that? The larger the sensor, the larger the lens that can let in enough light to cover a larger area of the sensor. As a result, the equipment is very large, expensive and inconvenient.
When high camera aperture matters
With insufficient light. For example, when shooting in a dark room, in the evening on the street. Such a lens will give the matrix a maximum of light. This is better than raising the ISO and end up with a lot of noise in the picture.
With a fast lens, you can shoot in places where artificial light and insufficient natural light cannot be placed. For example, a temple, a theater, a specific museum where you can not change the lighting of the composition.
In such lenses, as we mentioned above, an improved autofocus system. And even in difficult lighting conditions, the camera will still work quickly and confidently. And if you arm yourself with a tripod, you can take fascinating photos of the starry sky.
With this lens, you can take beautiful pictures even at night. Photo: wall.alphacoders.comA stylish and beautiful blurred background is an artistic technique that is available with such lenses. Depth of field decreases as the aperture is opened wider. Therefore, a fast lens allows you to make a blurry background, and make one object clear. This allows you to focus on the object, make it more voluminous and hide unwanted details from the background.
Aperture and lens choice
Such lenses help to take beautiful and unusual photos. But there are genres in which they are not needed. For example, shooting:
- for a clothing catalog;
- Items: furniture, accessories, decorative items;
- landscapes, nature;
- monuments, architectural ensembles.
In these cases, aperture is not important. Because you usually have to take pictures in a location with good lighting, from a tripod, on a closed aperture.
But to buy such a lens for the camera is when shooting:
- Events (e.g. weddings, graduations);
- portraits;
- reportage;
- creative (starry sky, unusual effects in the studio or outdoors, etc.).
Such equipment will help you create beautiful creative images that will become a worthy addition to your portfolio. We hope that our material has helped you understand what aperture is and what it affects.
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