Bokeh Explained

Introduction

ttartisan 50mm 1.4 m m-mount leica m10 sony a7riii a7riv sharpness bokeh resolution contrast review
Leica M10 | TTArtisan 50mm 1.4 | f/1.4

The bokeh quality – or a lens’ rendering for that matter – is probably one of the most discussed and maybe also most important aspects of a (fast) lens. While many people think only the focal length and the maximum aperture are important, there is actually much more to it, as I will try to show you in this article. This knowledge may also aid you in finding the best lens for your specific needs.

Sony A7rII with metabones Leica-M adapter and MS-Optics Aporis 135mm 2.4 bokeh loca
Sony A7rII | MS-Optics Aporis 135mm 2.4 | f/2.4

There are two main things to consider here: bokeh quantity and bokeh quality, which we will both have a look at.

I will mostly be talking about background bokeh here though, as foreground bokeh is more of a niche application and might also overcomplicate this article. I will also not talk about local pixel level adjustments to alter the bokeh rendering.

Quantity

zhong yi mitakon 135mm 1.4 bokeh bokehpanorama brenizer fast ultra fast portrait speedmaster review sharpness sony 42mp 61mp portrait woman
Sony A7III | Zhong Yi 135mm 1.4 | f/1.4

The quantity of the bokeh depends not only on the lens’ specifications or the distance relations in the scene, but also on the optical vignetting and field curvature characteristics of a given lens.

Maximum Aperture and Focal Length

What is a fast lens? A 50mm lens with a maximum aperture of f/0.95 probably is, same goes for an 85mm f/1.4 lens. Now a 35mm f/2.8 most people wouldn’t consider fast whereas a 400mm f/2.8 is considered a very fast tele lens, despite both having a maximum aperture of f/2.8.

canon ef 200mm 2.0 l is usm sony 42mp high res review 1.8 comparison sharpness bokeh resolution brenizer
Sony A7III | Canon EF 200mm 2.0 L IS | f/2.0

What becomes obvious here: focal length and maximum aperture are both equally important and if you divide focal length by maximum aperture you get the size of the entrance pupil, which is a good reference point to evaluate the “blur potential” of a certain lens. Bigger is generally better here, I already talked about this in my article about Brenizer/Bokehpanorama, so maybe have a look there if you are curious what lenses to use in order to achieve the highest “quantity” of bokeh in your pictures.

olympus super tele om 250mm 2.0 180mm 350mm 2.8 review hands on bokeh rendering out of focus
Sony A7rII | Olympus OM 250mm 2.0 Zuiko | f/2.0

The take away message from this section: all else equal a faster lens of the same focal length will (or should, see “optical vignetting” section) yield more blur and a longer lens with the same maximum aperture will also yield more blur (you need to adjust the distance to your subject for similar framing though).

I guess most of you were already aware of this ๐Ÿ™‚

Distance Relations

What is actually more important than the lens you use are the distance relations in the scene. To get the highest amount of blur your subject should be as close to the camera as possible and the background should be as far behind the subject as possible.

These three pictures have all been taken with the Laowa 35mm 0.95 set to f/0.95. In the first picture I am close to the woman, the background is blurred noticeably. In the second picture I am farther away from the woman, the background is still a bit out of focus.
Now in the third picture the distance to the woman is similar to that in the second picture, but that background is much closer and at this output size you can hardly tell it is out of focus at all.

How important the focus distance is also becomes very apparent when using macro lenses, at high magnifications – even when you stop down the lens a lot – the depth of field is thin as paper:

laowa 85mm 5.6 2:1 ff ii macro twice life size makro mirko 42mp 61mp resolution bokeh sharpness contrast
Sony A7III | Laowa 85mm 5.6 Macro | f/11

To visualize what I have written in the past two sections you can also use a Depth of Field Simulator. The following aspects can not be simulated there though.

Optical Vignetting

leica m10 review rangefinder messsucher comparison vergleich sony a7iii a7rii R2 42mp 24mp wide angle portrait
Leica M10 | Voigtlander VM 75mm 1.5 | f/1.5

Now when I said a lens with faster aperture will always yield more blur then a slower lens with the same focal length this is true for the center of the frame, but the corners can be a different story, as there is this thing called optical vignetting.

Leica M10 | Voigtlรคnder VM 50mm 1.5 MC II | f/1.5

In the center of the frame almost every lens will render a perfect circle, but only lenses with very low optical vignetting will keep this shape in the corners, as optical vignetting leads to the truncation of light circles towards the borders of the frame. This also leads to the depth of field increasing towards the corners, so most lenses will show a higher amout of blur in the center of the frame compared to the corners.

We will have a look at a few different lenses here and we will move from the center (left) to the extreme corner (right) and see how the shape and size of the light circles changes:

The Sigma 35mm 1.4 Art shows a very typical/average behaviour here. The MS-Optics 50mm 1.0 ISM shows very strong optical vignetting – considering its maximum aperture and size not surprising – the Sony FE 85mm 1.4 GM on the other hand is one of the lenses that show a surprisingly low amount of optical vignetting, therefore it can create more blur in the corners than even faster 85mm f/1.2 lenses.

I also included the Zeiss Loxia 85mm 2.4 in this comparison. Just looking at the specifications one would think the Sony FE 85mm 1.4 GM – when stopped down to f/2.4 – would show the same amount of blur as the Zeiss Loxia at f/2.4, but as you can see the difference is quite big not only in the corners but also the midframe area and this will be noticeable in the field as well.

A very high amount of optical vignetting can also lead to what is often referred to as “swirl”. There are certain lenses available that are designed to give this look (e.g. Petzval 85mm 2.2):

Nikon D700 | Petzval 85mm 2.2 | f/2.2 | ยฉ Petr Novak / Whistling Horse Photography

Field Curvature

If you had a look at the previous sections and you were thinking “yeah, I knew all that already” this is where it might get interesting for you. I already wrote in the previous section that due to optical vignetting the depth of field towards the corners increases, now we will add field curvature to the equation.

Field curvature can take on various shapes (e.g. V or W), but instead of discussing this we will have a look at this comparison. We are comparing the MS-Optics 50mm 1.0 ISM @ f/1.4 to the MS-Optics 50mm 1.1 Sonnetar @f/1.4. Same focal length, same aperture, so we would expect the pictures to look similar in terms of depth of field and bokeh, but as you might have already guessed, this is not the case here, not at all.

Focus in both pictures is on the front of the Lotus Esprit. Now the background in the first picture looks like I would expect (and find appealing): the boat in the background as well as the corners are nicely out of focus.
Now in the second picture the boat as well as the corners look almost as in focus as the car in the front. Both lenses show a very similar amount of optical vignetting, so what is the reason for this?

The reason is field curvature. Let’s imagine we are having a look at the scene from above. Now to make it more obvious we are at first assuming an “ideal” lens with zero optical vignetting and no field curvature (this ideal lens is actually what people often think all lenses behave like):

With the fictional “ideal” lens a bar with constant depth will be in focus and the bokeh in the corners will be the same as that in the center of the frame.

The 50mm 1.0 ISM shows “good” field curvature, despite high optical vignetting (which leads to the bar getting wider towards the borders) the corners are still nicely out of focus.

The 50mm 1.1 Sonnetar shows “bad” field curvature, so towards the corners the focal plane bends to the back which leads to the things farther away being in focus again.
Compared to the 50mm 1.0 ISM the depth of field is not bigger, just its shape is different.

laowa 45mm 0.95 world's fastest lens e-mount review contrast sharpness resolution bokeh vignetting coma
Sony A7III | Laowa 45mm 0.95 | f/0.95
Voigtlรคnder VM 50mm 1.0 nokton fle review sharpness comparison leica m10 24mp 42mp 61mp m11 bokeh vignetting coma
Leica M10 | Voigtlรคnder VM 50mm 1.0 Nokton | f/1.0 | 3-stop ND

Now this is something that you can neither find in a lens’ specification sheet nor its MTF graphs, only thorough testing or using the lens in the field can reveal this.

Rangefinder wide angle lenses designed for film (or Leica M digital cameras) also show additional field curvature on Sony cameras due to the thicker filter stack in front of the Sony sensors. If you want to learn more about this rather specific topic maybe have a look at our articles covering issues with rangefinder wide angle lenses on A7 series cameras or the Kolari UT modification.

Quality

mitakon 50mm 0.95 zhong yi optical dark knight speedmaster a7 series a7rii a7r2 a7rm2 a7s sony e-mount fe
Sony A7s | Zhong Yi Mitakon 50mm 0.95 | f/0.95

Optical aberrations can have a significant influence on the bokeh rendering and even though they are called aberrations their influence is not always bad.
Some aberrations, or their degree of correction, can either lead to softer (low contrast, glow) or harsher (higher contrast, outlining) bokeh.

Also keep in mind stopping the lens down can significantly reduce most of the optical aberrations, so stopping a lens down will not only reduce the quantity of the bokeh, it may also influence the quality (sometimes significantly so).

We already have an article explaining various optical aberrations, if you are not familiar with the terms I am using in the following sections it might be a good idea to have a look at that article first.

Spherical Aberration

Spherical aberration can have a huge influence on the bokeh and we have to differentiate between undercorrection and overcorrection.

As can be seen from the following comparison an overcorrection will lead to higher contrast and outlining (as well as increased sharpness) whereas an undercorrection will lead to lower contrast and sometimes even a soft glow around highlights.

Some manufacturers also offer lenses with overcorrected spherical aberration for those that are fans of the look, one such example is the Voigtlรคnder 35mm 1.4 Nokton Classic E. In a direct comparison to the Voigtlรคnder VM 35mm 1.7 Ultron (which offers a smooth bokeh rendering) the outlining of the light circles (a sign for harsh bokeh with double edged structures) is very obvious:

In the past an undercorrection of spherical aberration meant a lack of sharpness (the Nikon AF-S 58mm 1.4G is a good example of this), but the advancements when it comes to the manufacturing process of aspherical elements allowed the manufacturers to realize lenses that combine an undercorrection of spherical aberration – to achieve smooth bokeh – with good sharpness, some recent examples of lenses following such a design principle are the Sony FE 85mm 1.4 GM, Voigtlรคnder 50mm 1.2 Nokton E or the Sigma 35mm 1.2 Art DG DN.

Sony A7rII | Sony FE 85mm 1.4 GM | f/1.4
voigtlander 50mm 1.2 e nokton sony fast 50 bokeh sharpness 42mp resolution a7rii a7riii review
Sony A7rII | Voigtlander 50mm 1.2 Nokton E | f/1.2

Coma

Coma is an aberration astrophotographers usually care about a lot. A bit of undercorrected coma can actually lead to softer bokeh in the corners, a high amount on the other hand can lead to severe issues with point light sources, as bokeh highlights can take on obtrusive shapes like trapezoids or triangles:

zhong yi mitakon 50mm 0.95 m-mount leica m10 sony a7riii a7riv sharpness bokeh resolution contrast review
Sony A7rII | Zhong Yi 50mm 0.95 M | f/0.95
zhong yi mitakon 50mm 0.95 m-mount leica m10 sony a7riii a7riv sharpness bokeh resolution contrast review
Leica M10 | Zhong Yi 50mm 0.95 M | f/0.95

Astigmatism

A low to medium amount of astigmatism is usually nothing to worry about, but some lenses with a high amount of astigmatism can show very obtrusive double edge artefacts in the out of focus areas (license plate in the first picture, black bar on the document in the second):

carl zeiss jena flektogon retrofocus m42 prakticar 35mm 2.4 review sony 42mp a7rii a7rm2 a7rm3 sharpness close focus
Sony A7rII | Carl Zeiss Jena Flektogon 35mm 2.4 | f/2.4
zenitar 50mm 0.95 noctilux zhong yi mitakon SLRmagic sharpness resolution 42mp e-mount a7rIII a7rII bokeh
Sony A7rII | Zenitar 50mm 0.95 E | f/0.95

Longitudinal CA / “Bokeh Fringing”

Longitudinal chromatic aberrations (short: “CA” or “loCA”) lead to (usually) magenta and cyan outlining in the out of focus areas. Depending on the level of correction this can become quite obtrusive (and is also hard to correct in post):

nikon af-s 58mm 1.4g n nano high resolution bokeh portrait sony a7rII a7rIII a7rIV sharpness resolution lateral ca chromatic aberration aberrations
Sony A7rII | Nikon AF-S 58mm 1.4 | f/1.4
Leica M10 | MS-Optics 73mm 1.5 Sonnetar | f/1.5

Nevertheless: a perfect correction of longitudinal CA – as can be encountered with some lenses carrying an “Apo” tag – doesn’t necessarily lead to improved bokeh rendering. Voigtlรคnder’s Apo-Lanthar lenses for example show a rather harsh, high contrast bokeh rendering with a tendency towards double edged structures:

voigtlander vm 35mm 2.0 e apo-lanthar review 42mp 61 mp sony a7riv a7rii a7riii contrast resolution sharpness bokeh
Leica M10 | Voigtlรคnder VM 35mm 2.0 Apo-Lanthar | f/2.0

Conclusion

Leica M10 | MS-Optics 50mm 1.0 ISM | f/1.4

When deciding between lenses many people ask which lens is “sharper” and if you are mainly into landscape and architecture photography there is nothing wrong with that, but when dealing with portrait lenses: does this really matter?

Does a picture catch your eye because it has been taken with a lens that has slightly higher MTF than that of the competition, or is it the depth created by transition from areas-in-focus to areas-out-of-focus that draws you in?

laowa 35mm 0.95 worlds fastest lens review bokeh 42mp 61mp laowa venus optics venuslens fullframe contrast resolution bokeh optical vignetting fall off
Sony A7III | Laowa 35mm 0.95 | f/0.95

The thing is, unlike MTF (contrast and resolution), bokeh cannot easily be measured. It is possible to compare lenses and you might find you like one more than the other, but at a different focus distance or with a different background you might prefer the lens you have dismissed before. This is the reason I try to spend a lot of time on the bokeh evaluation when reviewing lenses and also have a look how they behave at different distances and in different scenarios.

Still, I cannot always discuss the effects of the different aberrations in great detail, therefore the idea was to summarize all of that in this article. I hope you found it helpful and that it can aid you in chosing lenses that give your pictures the look you desire.

Sony A7s | Zhong Yi Mitakon 50mm 0.95 | f/0.95

Further Reading

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My name is Bastian and I am your expert here when it comes to ultra wide angle lenses, super fast portrait lenses (ranging from a 50mm f/0.95 to a 200mm f/1.8) and I also have reviewed way too many 35mm lenses. Don't ask me anything about macro or wildlife shooting though.

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53 thoughts on “Bokeh Explained”

  1. Thank you for the nice article. MS optics is my favorite. I’d also like to suggest Takuamr M42 lenses for testing. have unique bokeh as well as specific imaging

  2. Very glad you wrote the article! nicely done and thank you. This was very helpful.

    I feel like the Nokton 50mm 1.2 almost perfectly balances spherical aberration correction, sharpness and micro-contrast. The VM 35 1.7 seems to do that well too. Unfortunately there don’t seem to be many ~85mm lenses that do that.

  3. Brilliant Article!
    I was very disappointed about my lens not producing round circle bokeh, especially for big aperture tele-photo lenses. But after reading your website, I realized that it’s a general problem. My solution is to use medium format lens on full frame camera body or attach full frame lens to apsc camera. I’m thinking about using apsc camera with sigma 105mm f1.4 lens ( about 160mm f2 full frame equivalent), it seems when using f2, the bokeh are super round in aspc format.

    Thank you for all the great articles!

    bokeh reference: https://www.cameralabs.com/zeiss-otus-100mm-f1-4-review/2/

  4. Great article.

    The point about field curvature, which might be of passing interest.

    Despite it being something “you can neither find in a lensโ€™ specification sheet nor its MTF graphs”, it has been argued that correction of it is “the pivotal problem of photographic lens design” and that *all* lens types can be considered a consequence of correcting that (and can be grouped accordingly).

    This isn’t really too dense of a read (I’ve never touched “applied photographic optics”) and recontextualises lens designs you may have a patchy awareness of.

    https://doi.org/10.1117/12.959088
    Or put it through Scihub, which has access to it.

  5. Thanks, Bastian, for another interesting and informative article.

    Although many photographers seem to concentrate on blurring out the background, it’s of course equally possible to enjoy more subtle effects. For what it’s worth, Mike Johnston*, the former editor of the American magazine Photo Techniques that may have helped English-speaking photographers focus on the appearance of the out-of-focus portions of their images, once flippantly crowned a nice Leica lens as the “King of Bokeh”–because he liked how that lens worked when he focused at a few meters distance with the lens closed down to around f/5.6 rather than at a wider aperture.

    I tend to do something similar, and I’m happy with what my Loxia 25mm or Voigtlander 50mm APO can do closed down a bit rather than wide open. I enjoy having the out-of-focus areas convey some context–and that, not coincidentally, helps me to avoid the distracting oval or truncated highlights that you showed are often produced by optical vignetting when compact lenses like mine are used at wider apertures.

    https://theonlinephotographer.typepad.com/the_online_photographer/2012/10/a-new-king-of-bokeh.html

    *Johnston added the “h” to “bokeh” to help his readers understand that bokeh (as in boke-aji) is a two-syllable word.

    1. Hehe nice one. I feel exactly the same. And thanks Bastian for the nice article about the 85gm. After reading this, I bought it and love it until today.

  6. In the field curvature section you write that “due to optical vignetting the depth of field towards the corners increases” but it should be decreases, right?

      1. you’re absolutely right, for some reason I read it the other way around ๐Ÿ™‚
        thanks for a really good article, as always

  7. Nice article as always, looking at the sample photos, did you really get your hands on a Laowa 45mm 0.95 or was that a typo and it really was the 35mm lens? If it’s the 45mm I’m stoked for it’s review.

    1. No typo. I am currently working on the review of the Laowa 45mm 0.95, it will be published on release day,
      which should be at the very end of this year, but I cannot give an exact date yet ๐Ÿ™‚

  8. great read, thanks for shedding some light on olverlooked lens characteristics.
    I find field curvature is a big black spot for many lens reviewers because its not the most obvious characteristic, but is actually important to how you should use the lens.
    While in wideangles its ususally covered on this blog, i wonder if it would make sens to add a paragraph for future reviews also of faster lenses.
    I remember Roger Cicala evaluates it by taking a photo of a grass slope and using “find edges” in photoshop makes it visible. Seems like an easy to do routine, maye u might consider.
    https://www.dpreview.com/opinion/7031211310/roger-cicala-field-curvature-pt-2

  9. One thing I’ve never quite solidly figured out is how Mitakon v3 50/0.95 is doing those “leaky” bokeh balls.
    Clearly not coma, but rather some unique internal reflection.

    My current guess is wide open the light does hit straight aperture edges a bit and forms this peculiar shape.

    1. I found out this often happens at night with bright light sources, so in that regard it looks like coma. But either way, I find it very distracting and detrimental to the quality of bokeh.

    2. It is mostly a combination of spherical aberration and optical vignetting.
      Some lenses with a high degree of undercorrected spherical aberration
      create sort of a soft halo around out of focus highlights
      (it also means highlights become a bit bigger than they should be,
      but with uneven illumination that is).

      Now towards the corners optical vignetting truncates those soft halos, so only on the edges a small part of that soft halo remains visible:

  10. This is a very interesting and useful article, I have learned a lot!
    After reading this one, one other article I would humbly suggest is about the design process of a lens and how modern (and old) lenses are designed. This could perhaps include an interview to a design engineer or expert.

    I am a physicist, with some modest background in the basics of optics, but it appears to me that the design of a new lens is such a multi-dimensional problem that I am not sure what exactly is the design procedure. I mean: how many parameters are optimized during the design? What comes out really by design and what by chance? How are choices made in this optimization process? A small list of choices the designer has to do I could imagine would include:
    – architecture of the lens (why are there so many apparently all valid ways of making a lens, even for the same focal length?); apart from obvious patenting issues, why is everybody not using the same architecture, after all?
    – choice of lens glass materials
    – cost of individual elements and of assembly
    – impact of architecture on the mechanics and required precision
    – …

    What are the correlations between these parameters (i.e. if I improve this aspect of the lens, what else gets negatively affected) etc.
    The article by Bastian and other articles give measurements on the end-product of what must have been a very complex optimization process, and I would like to understand better – if possible – what is due to choice and what came as a random and perhaps inevitable result.
    Perhaps I am too ambitious or even simplistic, but I would appreciate a bit more knowledge.

        1. Well, Dr. Nasse would have been the right guy to talk to, unfortunately he passed away a few years ago.
          Since then I have the feeling Zeiss mostly dropped out of the camera lens business, so I have severe doubts
          there is a high incentive to spend some time for this.

          Furthermore I have the feeling the latest design of their lenses (e.g. Batis) is also being carried out in Japan.

        2. There is a whitepaper that Zeiss published that deals specifically with this topic. I don’t have a link though it’s likely still searchable through one of the big search engines. Also, a close reading of Nikon’s 1000 and 1 Nights lens history series can be revealing.

          Zeiss’ paper spent a long time describing out of focus effect behind the point of focus. Simply put, looking at out of focus point sources –

          – Soap Bubble rendition comes from over-corrected spherical aberration (see
          Trioplan 100mm f2.8, Canon 50mm f1.4 FL/FD as examples)

          – Center illumination brighter than edge comes from under-corrected spherical aberration (see the very classic Nikkor-P 105mm f2.5 – both Sonnar and Xenotar implementations)

          – Evenly illuminated disk with soft edges comes from neutrally corrected spherical aberration (see Nikkor 80-200mm f4.5 and Sony Zeiss 16-70mm f4 ZA OSS)

          The examples I choose are just that, examples. Each lens can be characterized by its behind the point of focus rendition. The effect is easily seen. From a design calculation perspective lens designers have that sorted out as well.

          I hope this helps.

    1. I actually didn’t think of those when writing the article, now that I do I think a mix of both those things, but I will consider adding a section covering those.

  11. These are some of my favorite articles on this site. Thank you for your time and effort to stage and plan out example scenes with two lenses, with and without a given effect. There is so much to learn about how all the aberrations interrelate, and the ways in which traditional flaws can be positive features — or the opposite.

  12. Hi Bastian, I notice a picture taken by you on voigtlander website with the new 50/f1. Any idea when we will get to see your review or some pictures? ๐Ÿคฉ

    1. Voigtlรคnder is using (old) pictures of mine as general header pictures everywhere on their homepage which more than once caused confusion.
      I allowed them to use these pictures back in the day when they were still sending me review samples.

      So long story short: I did not get the chance to use this new lens yet, but I am trying to get an early review sample from Robert White Photography in the UK.

  13. Thank you for your great article! You are very busy writing the most articles this year! How about your team mates?

  14. I thought that here will be something said about working distance. The important thing to understand that the longer the distance between lens and the sensor – the bigger the bokeh will be. This is why it’s almost not possible to beat the depth of field of a 6×6 format.
    When you use 35mm equivalent lens on 6×6, the bokeh size will be approx the same as using 65 mm on full frame.

    1. This is all simple physics covered by size of the entrance pupil.
      The distance between lens and sensor is irrelevant, the size of the entrance pupil is important.

      A 25mm f/0.9 lens on a sensor with crop factor 2.0 will give the same field of view and bokeh (quantity) as a 50mm f/1.8 on a fullframe camera.
      The math also works in the other direction, 6×6 has a crop factor of roughly 0.55 (we ignore the different aspect ratios here…)
      so here a 91mm f/3.3 lens will give the same field of view and bokeh (quantity).

      Working distance will also be the same in all these cases.

      PS: you need to go large format to rival the DoF a fullframe 50mm f/0.95 or 85mm f/1.2 creates (let alone a 135mm f/1.4 or 200mm f/1.8).
      I am not aware of medium format lenses that can do this, therefore some people are using projector lenses with bigger image circles for this.

  15. Great article, though, I feel out of curiosity it would be a good exercise to try other formats besides 35mm . Fuji apsc and Olympus Pro lenses are interesting. I currently have the Olympus 45mm 1.2 and itโ€™s holding me back from getting the Sony 85mm 1.4 for my Sony, because the bokeh on that is beautiful ( Opticallimits and Lenstip were both impressed with itโ€™s bokeh).

    1. The format is irrelevant, only the entrance pupil is important, so no thanks.

      If you stop the Sony FE 85mm 1.4 GM down to an equivalent f/2.4 it will look better in every regard.

      1. Yes, I get that format is irrelevant. I was thinking of different lens construction. I watched a recent video by Peter Karbe in which he talked about the choices taken by Leica with regards to design,construction and polishing which made me even more curious about other manufacturers approaches. Thank you anyway, was a great article.

  16. I am not really convinced that pictures under Astigmatism section are showing bokeh influenced just by astigmatism. It looks just like background bokeh with overcorrected SA. I would expect astigmatism to produce just an oval shape bokeh oriented tangentially or sagittally (depending on source of astigmatism and whether the out of focus light is behind or in front of the focus bi-plane) and its effect would be the strongest close to focus bi-plane (where bokeh size is small) and weaker far from it (where bokeh size is biggest). In the middle between the two focus planes it might be a 4-point-star-shaped. See here (there is an example of bokeh with astigmatism far from focus bi-plane): https://www.nukepedia.com/gizmos/filter/defocus_aberrations

    Anyway I quite like the article in the way how each effect is illustrated (except the Astigmatism). However I think the biggest bokeh quality destroyer outside of the lens, the EFCS (with high shutter speed), should be included.

    I have an article on bokeh too, somewhat old (first version came out more than a decade ago), more technical and more disorganized ๐Ÿ˜‰ here: https://jtra.cz/stuff/essays/bokeh/

  17. What a great article. Love the way you write and, more important, you show your own super nice examples. Keep the good work

  18. ์ •๋ง๋กœ ์ข‹์€ ์ •๋ณด ๊ธ€์ž…๋‹ˆ๋‹ค.

    ์‹ค๋‚ด ์ •๋ฌผ ์ดฌ์˜์‹œ์— 50mm ํ‘œ์ค€ ๋ Œ์ฆˆ์™€ ๋‚ฎ์€ ์กฐ๋ฆฌ๊ฐœ ์ˆ˜์น˜๋ฅผ (์ด๋ฅผํ…Œ๋ฉด f1.4 or f1.8) ์‚ฌ์šฉํ•ด์„œ ์‚ฌ์ง„์„ ์ฐ๊ฒŒ ๋ ๋•Œ๊ฐ€ ์žˆ์Šต๋‹ˆ๋‹ค.
    1m ~2m๋‚ด์™ธ์˜ ๊ฐ€๊นŒ์šด ๊ฑฐ๋ฆฌ์— ์ดฌ์˜์ด์ง€๋งŒ ๋ฐฑ๊ทธ๋ผ์šด๋“œ ๋ธ”๋Ÿฌ์˜ ์™œ๊ณก๋œ ๋Š๋‚Œ์ด ๋Š๊ปด์ง€๊ณ , ํ”ผ์‚ฌ์ฒด์—๋Š” ๋ฐฐ๋Ÿด ๋””์Šคํ† ์…˜์ด ์žˆ๋Š”๊ฒƒ ์ฒ˜๋Ÿผ ๋Š๊ปด์ง‘๋‹ˆ๋‹ค. ์‹œ๊ฐ์ ์œผ๋กœ ๊ทธ๋ ‡๊ฒŒ ๋ณด์ž…๋‹ˆ๋‹ค.
    ๋‚ด๊ฐ€ ์ •๋ฌผ์‚ฌ์ง„์—์„œ ์ฃผ๋กœ ์“ฐ๋Š” ํƒ๋ก  90mm f2.8์—์„œ๋Š” ์‹œ๊ฐ์ ์œผ๋กœ ๋Š๊ปด์ง€์ง€ ์•Š๋Š” ๋ถ€๋ถ„์ž…๋‹ˆ๋‹ค.
    ์ดฌ์˜์žฅ์ด ์ข์„๊ฒฝ์šฐ ์‚ฌ์šฉํ•˜๋Š” ๋‹ˆ์ฝ˜์˜ 50mm f1.4g๋Š” ์•ž์„œ ์–ธ๊ธ‰ํ•œ ์‹œ๊ฐ์  ๋ฌธ์ œ๊ฐ€ ๋‚˜๋ฅผ ํž˜๋“ค๊ฒŒํ•ฉ๋‹ˆ๋‹ค.
    ์ด๋ฌธ์ œ๋ฅผ ํ•ด๊ฒฐํ• ์ˆ˜ ์žˆ๋Š” ๋ Œ์ฆˆ๊ฐ€ ์žˆ์„๊นŒ์š”. ์ƒ˜ํ”Œ์— 85mm gm ๋ Œ์ฆˆ ์„ฑ๋Šฅ์ด ์•„์ฃผ ์ข‹์•„๋ณด์ธ๋‹ค.
    ํ•˜์ง€๋งŒ ๋‚˜๋Š” ๋‹ˆ์ฝ˜์„ ์“ฐ๊ณ  ์žˆ๊ณ  50mm ๋ Œ์ฆˆ๊ฐ€ ํ•„์š”ํ•ฉ๋‹ˆ๋‹ค. gm๋ Œ์ฆˆ๊ฐ™์€ ๋ณด์ผ€ ์™œ๊ณก์ด ์™„๋ฒฝํ•œ ๋ Œ์ฆˆ๊ฐ€ ๊ถ๊ธˆํ•ฉ๋‹ˆ๋‹ค.

  19. This is a really good informative article

    I sometimes find myself using a 50mm prime lens and a low aperture number (like f1.4 or f1.8) for indoor still life photography.
    50mm
    I’m shooting at close distances, within 1m-2m, but I feel like the background blur is distorted and the subject has barrel distortion. That’s what it looks like visually.
    This is something I don’t get visually with the Tamron 90mm f2.8, which I use for still life.
    Nikon’s 50mm f1.4g, which I use when I’m in a tight spot, suffers from the aforementioned visual issues for me.
    Is there a lens that can solve this problem, the 85mm gm lens in the sample looks very good.
    But I’m using a Nikon and need a 50mm lens. I’m wondering if there is a lens that has perfect bokeh distortion like the gm lens.

    Translated with http://www.DeepL.com/Translator (free version)

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