We wrote earlier.) Its most important function is depth of field: for example, thanks to the aperture, you can blur the background while highlighting the object, or, conversely, leave everything in focus. 
1. What is aperture?
To put it simply in simple language, the aperture is the opening in the lens through which light passes to reach the sensor. According to the principle of operation, it is in some way similar to the human eye. And if we draw a similar analogy with the camera itself, it turns out that the lens performs the function of the cornea - it collects all visible light, sending it through the iris, which in turn expands or contracts depending on the amount of incoming light, thus controlling the diameter of the pupil. The pupil itself is something like a hole through which light passes further, deep into the eye, where it hits the retina. So, it turns out that the aperture and the pupil perform the same function: light passes through the aperture and hits the camera sensor, similar to the pupil and retina. The larger the aperture diameter, the more light enters the sensor. And in the same way, the larger the diameter of the pupil, the more light enters the retina.2. Aperture diameter
The analogue of the iris, which controls the size of the aperture, in optics is called the diaphragm. The function of the aperture is to, by increasing and decreasing the diameter of the aperture, limit the amount of light entering the photosensor.In photography, aperture is measured in f-numbers or f-stops, and by what less value f-foot, the larger size apertures. Many people find this confusing because usually a larger number implies a larger value, but not in this case. So, f/1.4 is larger than f/2.0 and even larger than f/8.0.
For a clear understanding, it is better to look at the illustration below:
The relationship between aperture size and f-stop value.
3. Depth of field
Another thing to know about aperture is depth of field - the area of the photo that is in focus:If the f-number is f/32, then both the foreground and background will be in focus. If you select f/1.4, the background will be blurred, leaving only foreground objects in focus. This is clearly visible in the images below:
The left photo was taken with an f-number of f/2.8, and the right with f/8.0
As you can see from this example, even a small change in f-number from f/2.8 to f/8.0 has a fairly large effect on depth of field. And if I had used an f-stop of f/32, the background would have been as sharp as the WALL-E in the second photo.
One more example:
Letterboxes – aperture is f/2.8
In the photo above, thanks to the shallow depth of field, only the word “Cougar” is in focus, leaving the space in front and behind the lettering blurry. If in in this case if an f-number of f/1.4 was used and the camera was focused on the letters, then only one letter would be in focus.
4. Lens aperture: Maximum and minimum
Each lens has its own limit on the maximum and minimum possible aperture diameter. You can see these values in the specifications of your device, they are usually designated as Lowest f-number and Highest f-number.
It's worth paying attention to the maximum value, as it shows how fast your lens is. So, a lens with the highest f-number, somewhere around f/1.2 or f/1.4, is considered fast because it can let in more light than, for example, a lens with an f/4.0 aperture. Therefore, lenses with large apertures are more suitable for photography in low light conditions. In addition, a wide aperture allows for better isolation of foreground objects from the background. So when purchasing a lens, you should carefully consider these parameters.
The smallest aperture value is not so important, since almost all modern cameras have an aperture of at least f/16 - which is quite enough for ordinary everyday photography.
aperture- hole) in optics - a characteristic of an optical device that describes its ability to collect light and resist diffraction blurring of image details. Depending on the type of optical system, this characteristic may be linear or angular dimension. As a rule, among the parts of an optical device, a so-called aperture diaphragm is specially distinguished, which most strongly limits the diameters of the light beams passing through the optical instrument. Often the role is like this aperture diaphragm performs frame or the edges of one of the optical elements (lenses, mirrors, prisms).Links
- Aperture- article from the Physical Encyclopedia
- Aperture // Photocinema: Encyclopedia / Chief editor E. A. Iofis. - M.: Soviet Encyclopedia, 1981.
- Lens aperture // Photocinema: Encyclopedia / Chief editor E. A. Iofis. - M.: Soviet Encyclopedia, 1981.
- // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional ones). - St. Petersburg. , 1890-1907.
see also
Wikimedia Foundation.
2010.
See what “Aperture (optics)” is in other dictionaries: A branch of optics that deals with the transmission of light and images through light guides and waveguides in the optical range, in particular through multicore light guides and bundles of flexible fibers. V. o. arose only in the 50s. 20th century IN… …
Great Soviet Encyclopedia
X-ray optics is a branch of applied optics that studies the processes of propagation of X-rays in media, as well as developing elements for X-ray devices. X-ray optics, unlike conventional optics, considers... ... Wikipedia The field of research in which the phenomena and processes of X-ray propagation are studied. radiation during its interaction with matter, and elements for x-rays are also being developed. devices. When considering issues of R. o. x-ray The range is conventionally divided into... The field of research in which the phenomena and processes of X-ray propagation are studied. radiation during its interaction with matter, and elements for x-rays are also being developed. devices. When considering issues of R. o. x-ray The range is conventionally divided into...
Physical encyclopedia
This term has other meanings, see Aperture. Aperture (from the Greek διάφραγμα partition) an optical device, an opaque barrier that limits the cross-section of light beams in optical systems (microscope, camera, ... ... Wikipedia The field of research in which the phenomena and processes of X-ray propagation are studied. radiation during its interaction with matter, and elements for x-rays are also being developed. devices. When considering issues of R. o. x-ray The range is conventionally divided into...
A branch of optics that deals with the transmission of light and images through optical fibers and waveguides. range, in particular for multicore optical fibers and bundles of flexible fibers. V. o. arose in the 50s. 20th century In fiber optic lighting details... ... numerical aperture in object space - (A) The product of the refractive index and the absolute value of the sine of the aperture angle. [GOST 7427 76] Topics: optics, optical instruments and measurements EN numerical aperture DE numerische Apertur FR ouverture nu ...
Technical Translator's Guide
Technical Translator's Guide
APERTURE
(Latin apertura, from aperire - to open). 1) return of fief estate to the owner. 2) a hole, a beginning leading into some cavity. 3) in medicine - opening a wound. 4) in optics - a plane for transmitting light rays., 1910 .
Technical Translator's Guide
Dictionary of foreign words included in the Russian language. - Chudinov A.N.
lat., 1865 .
apertura, from aperire, to open. Returning the fief to its master.
(Explanation of 25,000 foreign words that have come into use in the Russian language, with the meaning of their roots. - Mikhelson A.D. Aperture lat.
1) the effective aperture of an optical device, determined by the size of the lenses or apertures; corner a. - the angle between the outer rays of the light cone entering the optical device; numeric a. - product of the refractive index of the medium separating the object from the front lens of the microscope objective by the sine of half the aperture angle; determines the image illumination and resolution of the device;
2) a. (opened) antennas - part of the surface of complex antennas that emits or receives electromagnetic radiation under given specific conditions.
New dictionary of foreign words. - by EdwART,, 2009 .
Aperture
[from lat. apertus open] – physical 1) the angle between the optical axis and one of the generatrices of the light body entering the optical device; 2) numerical aperture - the product of the refractive index of the medium separating the object from the front lens of the microscope objective by the sine of the aperture angle (cm aperture 1)
Large dictionary of foreign words. - Publishing House "IDDK", 2007 .
Aperture s, and. (fr. aperture Explanation of 25,000 foreign words that have come into use in the Russian language, with the meaning of their roots. - Mikhelson A.D. apertus open).
1.
wholesale The effective opening of an optical instrument, determined by the dimensions of the lenses or apertures.
2.
glad. The part of the surface of complex antennas that emits or receives electromagnetic waves under given specific conditions.
Explanatory dictionary of foreign words by L. P. Krysin. - M: Russian language, 1998 .
Synonyms:
See what "APERTURE" is in other dictionaries:
In geometry, the deviation of lines passing through one point [source not specified 1102 days]. Aperture in optics is the actual opening of an optical device, determined by the size of the lenses or apertures. Corner... ... Wikipedia
- (from Latin apertura hole) ..1) in optics, the actual opening of an optical device, determined by the size of the lenses or apertures. Angular aperture is the angle a between the outer rays of a conical light beam entering the system. Numerical aperture... ... Big Encyclopedic Dictionary
Modern encyclopedia
- (from Latin apertura hole), active optical hole. system, determined by the size of lenses, mirrors or diaphragms. Angular A. angle a between the extreme rays of the conic. light beam included in the system (Fig.). Numerical A. is equal to n sin (a/2),… … The field of research in which the phenomena and processes of X-ray propagation are studied. radiation during its interaction with matter, and elements for x-rays are also being developed. devices. When considering issues of R. o. x-ray The range is conventionally divided into...
aperture- Dimensions of the surface of the test object through which the emission and reception of elastic vibrations occur. For narrowly directed transducers in traditional control schemes, the aperture is the size of the working surface of the transducer. For… … - (A) The product of the refractive index and the absolute value of the sine of the aperture angle. [GOST 7427 76] Topics: optics, optical instruments and measurements EN numerical aperture DE numerische Apertur FR ouverture nu ...
Aperture- (from the Latin apertura aperture), the actual opening of an optical device, such as a camera, determined by the size of the lenses or apertures. Angular aperture is the angle a between the outer rays of the light beam entering the optical system;... ... Illustrated Encyclopedic Dictionary
Perhaps one of the most difficult aspects of photography to understand is the aperture of the camera lens. Whether it's the expensive lenses of a professional camera or the magnification of a compact camera (most compact cameras control the aperture for you), the lens aperture will affect your photography in the same way. I hope that this article will help you gain basic knowledge on this issue and that you will successfully apply it in your future photographic life.
Basics
You've probably seen people talking about "fast lenses" or "lens apertures" and they mention f/numbers and other obscure terms. (We won't repeat everything possible options.) But what does all this mean? And in all these cases we are talking about the aperture or relative opening of the lens or aperture.
It is important to understand that photography in its crudest form is a process of capturing light and changing it. Naturally or not, different scenes or areas will have different light levels. And in order to work with all this as a photographer, we need to control the light entering the camera. And one way to do this is to control the aperture (or aperture) of the lens, which is responsible for the amount of light entering the camera's photosensitive elements (among other things). Another method relates to controlling the shutter speed (but this is not the topic of this article).
All clear? No? Well, imagine that in order for a photograph to turn out, a certain amount of light must hit the sensors (or film, if you use it) of your camera. Let's draw an analogy with water in a decanter (a strange, but very clear analogy). Let's assume that it takes 1 second to pour 100 ml of water from the tap into our carafe. If we need more water, for example 200 ml, then we can either increase the time during which the tap is open (this is analogous to changing the shutter speed or shutter speed), or increase the size of the tap itself so that it can pass a larger volume of water in that time. the same period of time (this is already an analogy for changing the aperture or diaphragm).
Hopefully the fog is clearing now. An aperture or diaphragm is a hole in the camera lens through which light passes onto the photosensor/film.
The f/number represents the size of that hole itself. It may seem strange, but the smaller this number, the larger the aperture is meant (so f/8 indicates a significantly larger aperture than f/22). Thus, by setting the smallest f/number you are opening the lens wide. Each increase in this number reduces the amount of light entering the camera by half. The lower the number, the more light passes into the camera, and the “faster” the lens.
Fast Lens
A lens is considered fast if it has a large aperture, i.e. lowest f/number possible. This is because the lower the number, the larger the hole and the more light can pass through the lens. This means that shutter speed can be increased significantly.
A fast lens is great for shooting in low light (music concerts, events in dimly lit rooms, etc.) or fast moving subjects (sports competitions, wild animals, etc.). If you need to photograph something or someone in similar conditions, then a large aperture will be an excellent solution.
Depth of field
Another aspect that depends on the aperture is the number of objects in focus, or “depth of field.” The larger the relative aperture of the photographic lens, the smaller the area in focus will be, and vice versa. Landscape photographers will often work with high f/numbers, with smaller apertures (f/22+) because it helps create a greater depth of field (where more objects are in focus). In other circumstances, it may be necessary for one object to be clearly in focus, and everything in background it would be blurry. In this case, a larger aperture is used, a smaller f/number to reduce the depth of field (f/1.4, etc.).
Using depth of field is a great way to play with your photos (those unfamiliar with full auto settings can try aperture priority settings; you set the aperture, your camera sets the shutter speed; see your camera manual for how to set this). At manual setting depth of field can produce very interesting images (just don’t think that a shallow depth of field is better; sometimes the result can really surprise you).
Lens aperture
"Aperture" is a term used quite widely in photography circles, so it's worth briefly explaining what it means. "Aperture" means decreasing the size of the aperture by increasing the f/number.
In conclusion, a lens wide open will have a large aperture, a small f/number and a shallow depth of field; stopping down one or two stops will reduce the relative aperture size, increasing the f/number.
Summarizing
I hope that now the concept of “aperture” will become less vague for you. Finally, to bring final clarity to this issue, it is worth citing the following dependencies:
Small f/number (f/1.4) = Large aperture (relative opening) = Shallow depth of field and a large number of light passing through the camera sensor (and slower shutter speed).
Large f/number (f/22) = Small aperture (relative opening) = Large depth of field and little light entering the camera sensor (and fast shutter speed).
Telescope aperture(D) is the diameter of the telescope's primary mirror or its converging lens. Roughly speaking, the more “aperturistic” the better.
The more aperture, the more light the lens will collect and the fainter objects you will see. That is, if you want to observe galaxies and nebulae, then do not waste time and money on telescopes with aperture less than 150 mm. - quite a suitable size for a beginner, inexpensive and uncluttered.
If you really want to get good quality images, do not overpay for excesses, but also do not bite your elbows because it is “a little bit lacking” - take a telescope with an aperture of 200-250mm. Images of deep space objects with such an aperture are black and white. Although, the colors of the brightest stars are already clearly different. In terms of price, size and weight, this is the limit for the vast majority of astronomy enthusiasts. Yes, of course, aperture is such a thing that it will never be enough for you, but there is “it would be nice”, and there is “the prose of life”.
If you want to see color pictures of galaxies and nebulae, then the more, the better. Accordingly, the prices bite. Colors appear consistently at apertures greater than 300-350mm. The largest store-bought telescope with an aperture of 16" (406 mm) costs about 80 thousand rubles. Its dimensions and weight are such that you can’t drag it out into the yard “just like that” every time... buy it Vacation home and build an observatory :-)
If you want to look at the Moon, then it seems that the aperture could be smaller. Indeed, the moon is already bright. But it's not just about the brightness of the image. Aperture It also limits the maximum magnification of the telescope. Therefore, more aperture It won’t hurt at all when observing the Moon (if the aperture is too large and the image is too bright, then darkening “lunar filters” are used).
The choice of aperture when photographing is especially important.
A light matrix or photographic film has the ability to accumulate photons of light. That is, with a long shutter speed with a small aperture, you can get the same bright photos as with a short shutter speed with a large aperture.
Therefore, a small apochromatic telescope ED80 with an aperture of only 80mm is often used as a lens. But each individual frame turns out to be of very high quality, without light halos and diffraction rays around the stars.
Three main schemes of optical telescopes, from top to bottom: lens (refractors), mirror (reflectors) and catadioptric (mirror-lens):
When comparing refractors and reflectors by aperture, you need to remember that refractors do not have a secondary mirror; all collected rays reach the eyepiece. And, in reflectors and catadioptrics, this very secondary mirror is installed in front of the main mirror and covers part of the light. The more mirrors and lenses in the path of light, the less of it reaches the eyepiece. Consequently, since the designs of lenses in telescopes are different, their aperture ratio in terms of millimeters of aperture cannot be directly compared.
For more information about this, see the article about