About aperture

In their everyday life, many photographers often mean the same thing under the words 'Aperture', 'Aperture', 'Relative aperture'.

About aperture

About aperture

If everything is greatly simplified, then the F number (aperture number) is responsible only for the ratio of the geometric aperture of the lens to its focal length - therefore you can still find the definition that the F number is called geometric aperture. In fact, aperture Is the ability of the lens to transmit light, and this ability is influenced not only by the ratio of the focal length of the lens to its diameter (i.e., geometric indicators). A huge role in the ability to transmit light is played by the optical design of the lens, which tends to transmit not all of the incident light.

An ideal lens would let in all the light that falls on it, but due to reflection, reflection and absorption by the optical elements of a real lens, only a part of the light flux reaches the photosensitive element, which forms the final image. Therefore, different lenses with different optical schemes, but with the same relative aperture, can create different exposures in photographs, all other things being equal. This is very often encountered in a movie where you need to mount a lot of short videos, for example, shot from different angles, into one big one. At the same time, if the scene is shot from different angles with different optics with the same F value, then in the final gluing you can get different brightnesses, which will look very bad when viewing. This is the most primitive example that videographers often cite.

To make it more convenient to work with photo and video equipment, there is a so-called T number (from the English 'Transmission' - transmission, transmission). The T-number is the F-number corrected for the light transmission efficiency of the lens. The T number indicates the equivalent of a lens with a specific F number that allows 100% of the light to pass through. For example, if a 50mm, f / 1.4 lens only transmits 50% of the light, then an ideal T 2.0 lens would match. The number T can be used in the same way as the number F.

Example. If we have a 100mm T 4.0 lens, it doesn’t matter which geometrical hole it actually is and what its F number is, it will still transmit as much light as any other lens with the same T number, for example, some 50mm T 4.0 At the same time, 100mm T 4.0 and 50m T 4.0 can have completely different values ​​of the number F. If you put a neutral filter on such lenses, you can say that their values ​​of the numbers F will be preserved, and the numbers T will change to the degree of dimming by the filter. Thus T-stop (an analogue of the step of the number F) is in many ways more convenient to use.

On the network, I met information that photographers cheatedindicating on the lens barrel is not the real aperture value. In fact, no one is deceiving anyone, just between the concept of "aperture" and "relative aperture" there are certain differences that an experienced photographer knows about. On the lens, the usual value of the relative aperture is indicated (it is also called the maximum aperture, or F number), but how much light such a lens actually lets through can sometimes only be found in the instructions for the lens.

When I wrote the text for this article, I found instructions for a modern lens Nikon Nikkor AF-S 35mm 1: 1.8G DX, re-read it from cover to cover, but did not find information about the light transmission of the lens. Therefore, you can still slander the manufacturer for incomplete information about the lenses.

Due to the different light transmittance, even small paradoxes with the f-number can occur. For example, let's take two lenses - Nikon 35mm 1: 1.8G DX Nikkor (lens for cropped cameras) and Nikon 35mm 1: 2D Nikkor (full-format lens). It would seem that the first lens has a slightly higher aperture than the second. But if you try to shoot using these lenses using a cropped camera, it may turn out that the amount of light projected onto the camera’s matrix with the first lens will be less than the second. This is due to the fact that the cropped lens has stronger vignetting at F / 1.8 and with different luminous flux losses in optical circuits.

Photo for paragraph separation :)

Photo for paragraph separation :)

Many aspiring photographers tend to use high-aperture optics for the common reasons - excerpts, more flexible control of depth of field, beautiful drawing and excellent image quality. But high-aperture optics give some more very pleasant (and maybe not pleasant?) Nuances.

The first of them I want to note the brightness of the optical viewfinder. High-aperture optics give a nice bright picture in JVI. With such lenses it is much more convenient to aim manually, you do not need to peer very much at JVI and squint your right eye. The human eye adjusts very well to the light intensity, and therefore you can’t always notice the difference with different lenses, but there is one. Personally, I tried to determine my personal sense of brightness. JVI with a fast manual aperture lens - Porst Color Reflex MC Auto 1: 1.2 / 55mm. Here's what I noticed:

  • The difference between F / 1.2 and F / 1.4 is not felt at all
  • The difference between F / 1.4 and F / 2.0 is almost elusive
  • The difference between F / 2.0 and F / 2.8 can already be easily caught, but on F / 2.8 in JVI everything is clearly visible and does not cause any discomfort
  • The difference between F / 2.8 and F / 4.0 is enormous, you immediately notice it. Visually working on F / 2.8 is much nicer
  • The difference between F / 4 and F / 5.6 is not very noticeable, but at F / 5.6 after F / 2.0 there remains a feeling of extreme limitation.
  • With further closure of the diaphragm, everything becomes faded.

Based on the experience (and some others), I came to the conclusion that the most comfortable values ​​of the maximum relative aperture for sighting are F / 2.8 and lower.

You can conduct your own experiment on brightness JVI your camera. This is easiest to do if the camera supports depth of field preview via JVI. If there is no such function, then you need to use a lens with manual iris control. The electronic viewfinder is not suitable for such a test.

Helios 44 bokeh with 8 petals

Helios 44 bokeh with 8 petals. Photo separator

Aperture optics not only gives a brighter and brighter picture in JVIbut also allows in many cases where more accurately and quickly handle the autofocus system.

Roughly speaking, the stronger the light flux from the lens to the mirror, the easier it is for the phase focusing sensor to focus. The first time I felt the difference was shooting in the studio for a long time, where I had a weak modeling light from the fixtures at hand. The high-aperture lens that I used for a half-length portrait easily clung to the subject, but when I had to shoot a group of people and use the standard zoom with an average aperture, it simply refused to focus in such light.

I suppose that high-aperture optics should improve the quality of focusing also in the Live View mode.

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In addition to improvements in the focusing system, the camera, with fast lenses under certain conditions, much more accurately produces and measures exposure. I can’t say for sure how and for what reasons this or that camera improves the operation of the exposure meter, but, based on my experience, for some reason I’m sure that there are errors in exposure with aperture optics much less.

In my practice, errors in exposure most often occur when using medium-aperture optics and when shooting on covered apertures. When using high-aperture optics at the same values ​​of the number F, errors are much less. Of course, small errors in exposure not critical if you shoot in RAW, but still this is a good plus of such lenses.

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Also, I notice that fast aperture optics give less rejection due to focusing errors when used on covered apertures. I assume that if a slight error was made when focusing on a fast lens, then during shooting, when the aperture is closed, a noticeable expansion depth of field zones just make up for this mistake.

Who does not know, then modern SLR cameras always perform focusing with the aperture fully open and close it to the set value only during shutter release.

For an example we will take a fast fifty dollars with F / 1.4 and a usual regular zoom with F / 3.5-5.6. We will shoot at 50mm and F / 6.3. If the focusing error was initially made at fifty dollars, then due to the closure of the aperture to F / 6.3, the depth of field will greatly expand and will most likely capture our subject. At the same time, if there was a focus error at the zoom, then a small change in the depth of field during the transition from F / 5.6 to F / 6.3 will not be able to compensate for inaccurate focusing.

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True, high-aperture optics have obvious drawbacks. One of them I want to highlight the diffraction threshold, which sometimes starts from F / 8. Super-fast lenses with f / 1.4 and f / 1.2 and below suffer especially from diffraction at very closed apertures. Usually the minimum F number they can use is F / 16. Low-aperture optics are less prone to diffraction because they need to perform less aperture maneuver. So the stock "dark" zooms at F / 8 only come to life and show excellent photo quality. This can be critical only for certain types of shooting, and the threshold is different for different lenses. The features and subtleties I have described cannot always be clearly shown, but over time they begin to be felt in practice and affect the work :)

↓↓↓ like :) ↓↓↓ Thank you for your attention. Arkady Shapoval.

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Comments: 129, on the topic: About the aperture

  • Alla Ivanova

    With the opinion of the Author, I agree. Me, about 50 / 1,4. From my observations, .. is as sharp as possible in the center (well, this is a large field!) At f3,5. By f8 (and earlier) the sharpness across the entire field is leveled and increased along the edges to “8”. Working lens with open. I use it as a portrait lens, light airy drawing with excellent sharpness.

  • Alla Ivanova

    I have a900 + three glasses. 70-300 / 4,5-5,6 G dark horror. The picture is very good from him, Bo Zeiss did. Shirik TAMRON 20-40 / 2,7-3,5. And Poltos 1,4 SONY. That current half did not require camera alignment. And, MHIMO, if you have several glasses, the CHAMBER should provide for the possibility of ADJUSTMENT. For example, on the “A” mount on cropped cameras, only a77 has the ability to adjust, all the “smaller cameras” 35-55-58-65-alpha cannot do this. And, I'm sure, from other manufacturers, only one or two cropped cameras support ADJUSTMENT. So! Premium glass from SONY 70-300, - adjustment -2. Tamron “SP” +2. Conclusion, gentlemen, if! You have several lenses, - the CAMERA should have the possibility of ADJUSTMENT (with the subsequent memorization of this very adjustment and the definition of the LENS, to which it "adjustment" refers). Alternative ... travelzum, but one. By the way! Not subject to adjustment, because. there are (often) that, in the range of 18-70 O.K. but 70-270 is horrible. or vice versa. Beware of zoom lenses with a value greater than ... "4".

  • Alla Ivanova

    Shooting a shoulder portrait at 50 / 1,4 by 1,4, you will have depth of field no more than 3-4mm. Ie, half of the eyebrow is CUTTING, half is not. The model sits half a turn. Allows, for example, to make the lips SHARP, and the eyes softly, ... or vice versa.

  • Alla Ivanova

    THANKS! Arkady for the most competent article. I just liked it. And examples and links ... RESPECT!

  • Pastor

    I would like to add a little more about t-stops. This is rarely discussed, but something interesting. It turns out, for example, that 50 1.2l has only 1.5 t-stops, and 50 1.4usm 1.7, that is, the difference in light transmission is very small. It is clear that the pattern and the depth of field are different, but the light transmission on a more expensive lens falls more.
    Perhaps someone would be interested in a separate article on Radozhiv (I would be interested), where this issue is examined in detail. After all, many are surprised that the automatic at 24-105 at 50mm and f4 (5.1 t-stop) sets slightly different shutter speeds than at 50 1.8 (which has t-stops 2.0) at f4. Well, in general, I wonder why manufacturers do not indicate such a useful value in the characteristics of lenses. At the same time, sometimes, zooms have better light transmission than fixes. 50 1.2L (1.5 t-stop) transmits 64% of the light, and 16-35 2.8 (3,2 t-stop) - 77%. Although, in theory, there are more glasses and theoretically, the relative losses should be greater, at least even in the lens body. Well, it would also be interesting to find tests that show how much the light transmission drops when the lenses are dusty or when a poor-quality filter is used, but I think that no one bothers too much with this - the losses are probably minimal.

    • Denis

      Obviously, the diameter also affects the transmittance (to the issue of zoom-fix)

    • Jury

      The text is big and the question is narrow, but there is still no clarity.
      The easiest way to understand the geometric aperture is by comparing the fixes fifty fifty / 50 and macro 1.4 / 50
      The aperture ratio of 1.4 is greater, and 2.8 is lighter due to a different optical scheme. And not only brighter, but the resolution is higher and the microcontrast is different.
      Therefore, all who say that aperture brighter even knowing about the light transmission, cause confusion.

  • tortik

    You confuse something:
    http://www.dxomark.com/About/Glossary/Help/Transmission-score
    The value of T-stop is proportional not to light transmission, but rather to the degree of light loss. If one lens has a Tstop 1.5, while the other 3.2 has a bright first, not the second.

    For very, very many lenses, the Tstop value has been measured. This information is of the utmost importance. Without understanding the theory, it remains only in practice to learn what is what for years and many photographers do not succeed, although they do not need it. Most often, if Photographers achieve excellent results, they still don't understand how it works. Trial and error is for the highly enthusiastic and professional only. Choosing lenses without understanding optics is an unaffordable luxury today.

    What conclusions can be drawn if the whale 18-55 with a stabilizer of 2.5-3 stops with a value of Tstop = 5 is compared with a fix of 50 without a stabilizer and Tstop 2.2?
    What, ceteris paribus distortions, will the application be optimal and what are the limiting factors.

    Mind you, I am not specifying either the “aperture” so beloved by photographers, or anything else. All this is superfluous, just the initial data and understanding of the principles of operation of modern lenses are enough.

  • ARSEN

    FATHER TEACHED ME TO FILM IN 1977. I filmed on his KIEV 19 I was then 16 years old. PHOTOS PRINTED TOGETHER .. IN 1982 I SHOOTED WITH ZENIT NOW I AM 50 WITH A TAIL AND I SHOOT ON NIKON D 5200 SUPER SHARPNESS CONTRAST AND OTHER THIS YES .. IT IS UNDERSTANDING .. BUT HELIOS ON NIKON GIVES THE VIRTUAL PHOTO ...

    • Andrei

      He doesn’t give out liveliness, he himself fell for it at the first acquaintance with Soviet optics, these friends are disgusting contrast, mediocre sharpness, etc. From an artistic point of view, maybe someone likes it. For me, these are remnants of the past and a dead end for the photographer, a cheap Chinese is not comparable better and more convenient in everything, but unless unless the goal is to hit someone

  • STANISLAV

    at 50 YEARS OLD I DECIDED to take a closer look at the photo …… .. Reading your comments I get real pleasure… ..Now, when searching on the Internet, I immediately look for your icon …… ..
    Well done, you write in such a way that it is always clear !!!!!!!!!!!!

  • Pauro daburu

    I partially disagree with the author. Try burning wood with sunlight through a 150mm magnifier and a ∅30mm magnifier. Focus the light collected by the lens surface into a 10 mm spot. In the first case, the wood will quickly char, and in the second it will not even burn your fingers - because of the difference in the amount of collected light. It's the same with the lens. A lens with a large front lens will collect more light. This is a good start. But if this light is partially lost on the filters or just gets past the matrix, the cloud of photon particles will die aimlessly. The author confuses aperture ratio with system capacity. The aperture ratio is the sum of the diameter of the front lens, the light transmittance of the system at a specific focusing distance and the ratio of the light caught by the matrix / escaped by the light. This will be consonant with the law of conservation of energy.
    This will also explain cases when they try to compensate for the poor quality or inefficiency of the optical system by the size of the front lens and get an average result.
    I'm not a photographer at all. But if my knowledge of physics left after school is limping, then help me become more literate.

    • Oleg

      But will not the excess light be cut off by the diaphragm?

      • NE

        aperture - relative aperture of the lens.

    • Dmitry V

      That's most likely just like that! By analogy with an optical communication cable, transferring the concept to the lens, namely: the light flux passing through the lens loses its power and the lower the lens manufacturing technology, the greater the loss of light that turns into heat and does not reach the matrix. Therefore, it is necessary to increase the power of the incoming light flux by increasing the diameter of the front lens in order to compensate for these losses in the glass. Therefore, third-party manufacturers have larger diameters because the quality of the glass is worse than that of the branded ones. In addition to the quality of the glass, light interference is also affected by the interference of light in the lens, i.e. redistribution of light intensity, and this is the quality of the lens manufacturing technology. Therefore, not a fact, the nikon 18-105 is fundamentally different from a third-party manufacturer with f1.8 !!

  • Andrei

    The topic discussed in the article and comments is very interesting and topical for me, how much I did not try to find an answer why, so that with an equal hole, different lenses for transmitting light are different, I did not derive the formula, the only optical scheme. But the only thing I will say for sure is that lenses with 3,5 are brighter than with 1.8 and using such a thing is extremely pleasant. Down with the dark lenses !!!)

    • Andrei

      And complement. What is most curious (from my observations), plus no less excerpt here lies in the fact that according to the sensations of DD more, although this cannot be, but it is perceived as

  • anonym

    But it’s interesting, does the exposure meter record the power of light? or set aperture number?

    • Arkady Shapoval

      The exposure meter shows the exposure at the set parameters, including illumination. You can roughly say that it captures the power of light.

  • anonym

    Sorry, I’ll clarify. But it’s interesting, after all, an exposure meter captures the intensity of the light transmitted through the lens, and then recounts it depending on the installed aperture?

    • Denis

      and nothing else

  • Catherine

    Thank you for the article!

  • Dmitry V

    well, so what does it mean that a fast aperture lens outperforms the dark only in low light in that the former will precisely focus and correctly set the exposure? and on the street on a sunny day there is no difference? (except blur the background)?

    • Arkady Shapoval

      Not really, at equivalent aperture values, usually with a fast lens, the image quality is noticeably higher.

      • Dmitry V

        and what is the image quality :( compared to 2 1,8 and 3,5 lenses under the same conditions):
        1. detail (light and high-quality dark the same in good light)
        2. focus (same)
        3. noise (identical)
        4. moderate sharping (equally)
        5. lighting (same)
        6. chromaticity (here there may be a difference in the quality of workmanship)
        7.jpg compression (same)
        8. spots on the matrix (equally)
        9. moire (there may be a difference or maybe not)
        10. vignette (there may be a difference)
        Well, here, I think that only in 3 positions the image quality can differ.

        • Dmitry V

          …. and if on a sunny day you hold down f to 8 at 18-105, then these 3 positions may not exist. Thanks for the dialogue!

          • Arkady Shapoval

            As an example, take any 50 / 1.8 and whale 18-55 / 3.5-5.6. As a result, the whale lens at 50mm focal length will have F / 5.3-5.6, which is about 10 times darker. Even during the day, in the shade at a minimum and a comfortable shutter speed of F / 5.6 may not be enough.
            1. Detailing at fifty dollars at F / 5.6 will be several times higher than at 18-55 / 3.5-5.6 at 50 mm focal length and F / 5.6
            2. Focusing (its tenacity, not speed), unfortunately, in the general case, 18-55 / 3.5-5.6 by 50 mm will be worse for the vast majority of CZK, the reason for this is simple - F / 5.6 is the aperture limit for a huge number of phase focus sensors. Actually, that's why lenses with F / 6.3 start having focusing problems with simple focusing modules. I quite often note this nuance.
            3. Other optical indicators, such as aberrations, vignetting, etc. in general, are reduced with aperture. While the 18-55 / 3.5-5.6 will work in the open, the fast aperture lens will work in the covered aperture (with aperture).
            In fact, your message is not entirely clear, can you please state it more clearly. Thanks.

            • Dmitry V

              Dear Arkady, let's figure it out, maybe I didn't understand something: we have 50 / 1,8 (fixed) and 50 / 5,3 (zoom). You write that the second is 10 times darker ??? how is it, you contradict yourself in this article, you are comparing the f-number and the aperture ratio, here is your text: "there are certain differences between the concept of" aperture ratio "and" relative aperture ". By no means can we say that closing the aperture we reduce the aperture ratio! The aperture ratio is constant constructively (I assumed this above on the forum). Further, I claim that on a sunny day, a photo taken with a 50 / 5,3 zoom will be the same as with a 50 / 1,8 prime. In the first case, the shutter speed will be approximately 1/1000 s, and in the second - 1/4000 s, but the end result will be approximately the same (not counting the bokeh). These lenses will differ if the luminous flux comes into them less (at dusk or indoors), when in the “aperture 50 / 1,8 the loss of light will be less than in 50 / 5,3, even if their shutter speed is different, all equally loss of color tones and shades in glass 50 / 5,3 will affect. So I think where the difference is. But again, if you use good light in the room, then again, probably, we will not see much difference. If not, correct me.

              • Dmitry V

                reducing the aperture, we reduce the luminous flux, which can always be compensated by shutter speed. (we close the tap with water, but increase the filling time of the container :-)

              • Arkady Shapoval

                You must have confused something in terms of “aperture” and “exposure”. Aperture expressed in T-stops usually correlates well with f-number F. Of course, T and F should not be confused, but usually the difference can be neglected, calling the f-stop value. This article simply shows those "certain differences" that are (literally from the article).
                The values ​​of F / 1.8 and F / 5.6 really differ by 10 times (to be precise, by 9,68 times). T-feet + - differ in modern lenses in approximately the same way.
                In general, photographs at 50 / 5,6 and 50 / 1,8 will be different, their exposure will be the same. And not 1/1000 and 1/4000, but 1/1000 and 1 / 10.000 (the difference in exposure is 10 times, not 4 times). By the way, you are also wrong about the twilight, the same exposure can be obtained in the same way - by increasing or decreasing the exposure.
                Once again, the same exposure can be obtained with anything and with anything. But this does not change the case in matters of luminosity (and it does not matter if this is pure T or F).

              • Valentine

                Not so, of course. You just tried to calculate the same conditions for the exposure of the frame. That is, all other things being equal, the frame will be exposed the same for the F2 + 1/800 pair and for the F4 + 1/200 pair. Please note that in real conditions the picture from two different lenses, as well as the exposure of the frame (calculations are based on geometry, but in reality there are still many physical quantities) will differ. Following your own reasoning, imagine that you are disassembling your “dark zoom” and replacing the aperture mechanism in it so that now the aperture opens up to F1.8. Do you think your lens will shoot just as well at F1.8 as a real high-aperture prime?

              • Valentine

                He wrote to Dmitry, did not see the answer of Arkady, who already explained everything perfectly about the exposition.

          • Valentine

            Dmitry, until you try it yourself, you will not understand. The difference between two lenses with the same EGF at the same apertures can be very, very significant, even if we are talking about well-covered apertures. They can not always discern the differences even on open apertures, noting more often some secondary signs and not paying attention to the drawing itself and the elaboration of the nuances of the scene. As an example, the pair test Nikkor AF-S 35mm f / 1.8G DX and Nikkor AF-S 35mm f / 1.8G ED: http://velo-foto.ru/obzor-nikkor-35mm-f1-8g-dx-i-nikkor-35mm-f1-8g-ed/ Read, this is funny.

  • Dmitry V

    on the website http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx conducted research on 2 lenses: 18-105 (50/5) and 50 / 1,8 (50 / 5,6) and according to my subjective visions:
    - sharpness (lens image quality) - I did not see the difference, including the darkening of the picture due to the luminosity of the fix. Here is the vaunted fix.
    - vignette - there is a difference, but not 10 times.
    - distortion - there is a difference, but not 10 times.
    - lans flare (flash) - not much difference in 2 hares.
    that’s all, all other judgments are deeply subjective.
    According to these tests, the competitor 18-105 only fix 85 / 1,8 / 1,4 That's where there really is a difference in sharpness and aperture for darkening the picture.

    • Dmitry V

      …… for a large set, except for bokeh, there is no difference by 1,8

      • Valentine

        Either they did not learn to see, or they looked something wrong. In my opinion, everything is obvious, click on the image to open it in a larger size:Canon 50mm

        • Valentine

          + These tests reveal only a separate characteristic of the lens, and there are actually a lot of photographic nuances. With experience, you will begin to understand the difference.

        • Valentine

          I took a slightly different pair for comparison, because the pictures from them had the same size, which allows them to be adequately compared. The pair you are writing about produces pictures of different sizes, which makes a head-on comparison difficult. Nevertheless, to illustrate your doubts about the difference between fix and zoom (I will repeat - by the only characteristic on the basis of which you make a conclusion about the quality of the lens as a whole), I believe that the above picture is suitable.

        • Dmitry V

          you're talking about canon and I'm talking about nikon

        • Dmitry V

          I agree with you, on your example the difference is very noticeable, the same as with Nikon 18-135, I'm talking about 18-105, which is radically different from others.

          • Valentine

            Well then, look at your pair (just keep in mind that these are screenshots - it's better to duplicate the parameters on the site). The difference is obvious, why you do not notice it, I do not know. And again, you focus only on one characteristic, which is probably important for technical equipment (for example, for a rare book scanner by photographing pages), but not for real photography.
            Nikon 50mm

    • Peter Sh.

      Dmitry, you are trying to contrast the spherical horses in a vacuum to the live experience of photographers.
      What do you want to prove? What is Arkady wrong? Based solely on his empirical findings, without personal experience of shooting in the real world.
      You seem to have nothing more to do.

      • Dmitry V

        I am an engineer and I trust the laws of physics confirmed by laboratory research, and everything else is subjective, like look at the difference between images in the park. everyone sees differently.

        • Vitaly N

          Well, the dullness of the light. They began to argue, not even knowing about the quadratic dependence of light transmission on the diaphragm. You about Thomas, you about Yerema.

        • Vitaly N

          If you are an engineer and believe in physics, count the number of lenses in the zoom and fix. The laws of physics have not been canceled - the more boundaries of the transition of the light flux, the more distortions and re-reflections are introduced. And I stopped believing the "laboratory" measurements after one match 18-105 and 18-140, where incorrect focusing was clearly visible, but the author assured about the worst sharpness. From personal experience I will confirm that fixes are better.

        • Peter Sh.

          1. Following the laws of physical and geometric optics, the use of black and white targets for lens tests is absolutely useless.
          2. The only laboratory studies that have scientifically based results can be carried out at the research institute. The rest cannot be used for any serious conclusions for obvious reasons.

          As one of my colleagues said - do not read Wikipedia, you will become a goat.

          • Michael

            Well, something is absolutely critical. For these targets, it’s possible to understand approximately what the link shows, and you can also compare. As an analogue of a brick wall, it is quite suitable.

            • Peter Sh.

              No, nothing can be understood. The main task of each lens is to bring the focus points of the rays of all colors of the visible spectrum as close as possible. Moreover, in completely different conditions. With different light sources, different brightness and diffusion, at the same time. When light bounces off dissimilar surfaces, in three dimensions.

              Black stripes on a piece of paper under a flash simply can’t create anything similar, literally nothing. This is nothing more than brainwash from marketers.

            • Peter Sh.

              Here is a picture that would be clearer what is at stake:

              image

              • Michael

                Well this picture is more likely to explain the friging. Although your idea is clear and justified. But still, it is worth sharing the concepts of resolving the lens and its behavior in difficult conditions (including those specified by you). Taking pictures of such pictures even from the monitor screen, I perfectly see the difference in the resolution of the lenses, the difference in the center-edge. It is clear that this is not a panacea, but not such a useless thing.

              • Peter Sh.

                You probably wanted to say chromatic aberration?
                There is no need to confuse cause and effect. Fridging and chromatic aberrations (which are not the same thing) are precisely the artifacts of splitting the focus into chromatic components. Those. in some places, the lens optics can not cope and can not collect the focus back to one point.

                Of course, the frequency-contrast characteristic also plays a role in the overall picture quality. But this is only one characteristic, and it cannot by itself determine the quality of optics and, moreover, the final result of the work of this very optics.

              • Michael

                Certainly.

              • Peter Sh.

                I'm wrong here, I apologize.
                Fringing will probably still be freezing.
                This is not just called, most often chromatic aberration.
                Although in fact it is astigmatism. Yes, throughout the frame, thin bright rays next to the main ones are much lower in brightness.

              • Michael

                Well yes. Friging is longitudinal chromatic aberration. It’s just that the question was not a bit about that, so do not focus attention)

          • Arkady Shapoval

            As the classic wrote - every second anonymous author can calculate a 20 lens lens made of crystal and achieve zero aberrations. But none of them can show a single good photograph.

  • Igor

    For a long time, I also compared the lenses according to the table. And the 18-105 was no different from 35mm. And there were doubts about buying a “fix”. But when I got this “fix” 35 mm 1.8, it makes a difference. And all the negatives aside 35mm is a thing of the past; it shoots and shoots well, even great.

  • Eugene

    Good afternoon friends.

    I have an old canon 60d with a whale lens 18-135.
    Somehow I needed to shoot portraits on the background of the action, but I wanted to blur this background. So I met with a fix 50mm 1.8f. I remember how I was surprised at a higher definition.
    And now about the aperture, the fix on the aperture 5.6 was on the step of the whale lens !! A sharper picture, or rather, autofocus falls into sharpness, but much darker!
    Recently, for the sake of experiment, I took the same fix, but fresher, with an STM drive. All the same, he became even a little sharper, but also a step darker than a whale.
    The area of ​​the front lens catches your eye, it is clear that in the zoom there are more elements and more losses inside the lens, but the area of ​​the front lens of the whale is 6-8 times more than that of the whale.

    I also got a manual fix from samyang at 85mm 1.4ph. When I compared it with a whale at 5.6, the samyang was one step lighter than a whale. I understand that there is less loss inside due to better lenses and fewer lenses, but Samyang also has a larger front lens area by one and a half to two times.

  • Ivanych

    You can add about the problem of shift focus on fast fixes

  • Vladimir

    I have a Sigma AF 24-70 F / 2,8 and a nikon 70 -300F / 4,5-5,6 AF-S VR. When viewing pictures and their accompanying information "properties", on the first lens the aperture is displayed 3,0, 4,3 on the second lens 5,0-70, that is, 4,3 - 300 and 5,0 - 4,5, although the aperture is set to 5,6 and 90 this means the lens is brighter than stated. Lenses have been tested on Nikon D300 & DXNUMX

    • Pokemon

      I also had two different age Sigmas 28 / 1.8 displayed.
      Ancient 28 / 1.8 High speed wide and 28 / 1.8 EX DG Macro. Everywhere as 28 / 1.6, although the former was noticeably darker than the EX DG.

  • Alexey

    Briefly everything a photographer needs to know about aperture.
    1. This is the ratio of the amount of illumination of the created image to the brightness of the displayed object.
    2. It is proportional to the square of the relative aperture of the optical system.
    3. Separate the geometric and effective aperture ratio.
    4. Geometric proportional to the square of the geometric relative aperture of the system: Qgeometer. = (D / f) 2, where D is the diameter of the pupil of the system, f is the back focal length. These geometric parameters set the maximum possible effective aperture ratio, but have a theoretical limit due to the wave properties of light.
    5. Effective, this is what the photographer needs, always less geometric, since it takes into account the light transmission coefficient of the system, which degrades the aperture performance.
    6. The optical design has little effect on the luminosity through the coefficient of light transmission.
    7. On photographic lenses, they indicate the geometric aperture ratio, which limits information content, on cinema lenses, they honestly indicate the effective aperture ratio.

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