On the subject of Depth of Field/"Bokeh"

[mrpengun]

I've seen lots of people advertising that a larger number of <EDIT> Aperture </EDIT> blades means a more pleasing blur in depth of field.

Then it struck me: the smaller depth of field means, of course, that the lens is wide open--e.g. no shutter blades impeding... I've never noticed a DoF difference between the two most open apertures (where, if the # of <EDIT> Aperture </EDIT> blades matter, then the difference should be largest). Therefore, the claim that the number of <EDIT> Aperture </EDIT> blades has any affect on the appearance of things outside the focal plane must be completely false... right?

<EDIT>
Thanks to Bjorn below for pointing out my miss-speak; should be aperture blades; not shutter blades.

[Oren Grad]

No, that's not right. The shape of the iris, along with the optical design of the lens, indeed affects the blur character. Read Harold Merklinger's article:

http://www.luminous-landscape.com/essays/bokeh.shtml

[mandoman7]

At most aperture settings the the edges of the aperture blades are defining the shape of the opening.

[Bjorn Nilsson]

I've seen lots of people advertising that a larger number of shutter blades means a more pleasing blur in depth of field.
...

In short, the number of shutter blades doesn't have any impact on the any parts of the picture. This because the shutter operates by being fully closed, then it opens very fast to fully open, to eventually fully close very quickly again. What you've probably read (At least what I've read) is "the number of aperture blades ...".
But the aperture (opening) blades on the other hand are in the same position over the whole exposure time and in a way shapes the blurry parts of the picture. (This of course given that you stop down the lens from fully open aperture.)

//Björn

[Frank Petronio]

I think having a round iris probably makes a difference around the middle apertures, when the lens is wide open or only partially open, even a hexagonal shaped opening isn't going to give you little hexagonal flares -- you need to be stopped down a bit for those hexs to show up.

I don't know if the quality of the bokeh is determined by the shape of the iris, all I know is that hexagonal flare patches are ugly and rounder ones are kind of nice.

[Ken Lee]

http://www.kenleegallery.com/images/tech/brasslens.jpg

Those old-time lens designers were some pretty smart physical scientists.

It seems to me that used lots of blades, because they explored and understood the issues.

[GPS]

I dare to say, the new-time lens designers are not less smart physical scientists. They too understand the issues...

[Struan Gray]

<nitpick>


In short, the number of shutter blades doesn't have any impact on the any parts of the picture.

Not quite true. At high shutter speeds and wide apertures, the true aperture becomes the time average of the shutter opening, which in LF and other leaf shutter lenses is a rather beautiful flower shape. Seen here:

http://www.largeformatphotography.info/forum/attachment.php?attachmentid=18358

<nitpick>

And to the OP: if you know what to look for, the difference between a circular aperture wide open and a polygonal one when slightly stopped down is clear - if you have the sort of subject which shows this sort of thing up. The texture of busy backgrounds can change quite dramatically, especially with lenses with pentagonal apertures.

[mrpengun]

I've read through the Luminous Landscape article now; but I think the question still remains for "real-world" situations.
The article shows that the shape of the iris matters, but not how much in relationship to the properties of the lens. (I remember reading a primer on MTF charts that made a claim as to be able to get a rough estimate of the Bokeh from the charts).
Additionally, it does not show how much more "standard" iris blade options will change anything. A circle made of 13 blades vs. a circle of 8 or 10 will not be near as pronounced as the triangle used in the article.
Nor will they make any difference if your aperture is wide open (providing the iris blades clear outside edge of the lens--as the last image in the article shows).
I think what I was trying to say is that the "answer" is much more complicated than simply "more iris blades = better".
Which we seem to be in agreement over :-)

<edit> having some typing issues all around...

[GPS]

http://www.kenleegallery.com/images/tech/brasslens.jpg

Those old-time lens designers were some pretty smart physical scientists.

It seems to me that used lots of blades, because they explored and understood the issues.

It seems to me that the bokeh "story" is quite a young one. Did anybody speak about bokeh in the beginning of the 1900s?
Beside that, if it is true what Struan says (citing Merkling) does anybody think that the old-time lens designers were after a pleasing bokeh in their lens design (not in the number of aperture leaves)?? I don't think there is any mention of it in the scientific optical literature.

[Jim Galli]

A lot of hair splitting goes on. Bokeh is largely unquantifiable. What is it you are looking to achieve. Beautiful bokeh is an expensive and seemingly bottomless pit. Wade through my web pages for a taste. Most folk though don't see the nuances. What you've got out in front of the lens is 98% of the picture if the bokeh is 2%. Still, I've spent a lot of money and had a lovely time exploring that 2%. I'm not done yet.

[mrpengun]

It seems to me that the bokeh "story" is quite a young one. Did anybody speak about bokeh in the beginning of the 1900s?
Beside that, if it is true what Struan says (citing Merkling) does anybody think that the old-time lens designers were after a pleasing bokeh in their lens design (not in the number of aperture leaves)?? I don't think there is any mention of it in the scientific optical literature.

I would agree--my knowledge of photographic history is much stronger than my knowledge of photographic practice :-)
In terms of history, the monkey-wrench would be pictoralism. Prior to that, it can be said (over-simplified, of course) that there was a push for ever-increasing sharpness. Folk like Juliet-Margaret Cameron's portraits were part of a 'soft focus push', although in some of her letters and diaries claims to simply "have forgotten to use the fine-focus" (a paraphrase).
To that end, it is important to view the growth of photography in relationship to painting and criticism--not to mention the legal positions of printing and books (e.g. Talbot's patents on Paper-negatives for printing). Many established art institutions kept trying to push photography away by sort of 'altering the goal-posts' for its acceptance. Eventually (again, over simplifying for the sake of brevity), movements like pictoralism take hold because they show photography as an artistic craft just like any other, with many of the same skills and finished products.
In the early 20th century, Modernism and New-objectivity again promoted sharpness.

However, while we're on the subject, will tilts and swings change the affective shape of the iris? not to mention greatly affect the lens-properties with regards to DoF affects?

[rdenney]

It is subjective, to be sure, but it's not non-quantifiable. We just haven't developed a good model yet. But it would certainly be possible to do so.

Until then, and until photographers learn how to interpret such a model in terms of their own tastes, the only advice is to keep the lenses that make images one things are beautiful and sell the rest.

I've also considered this at some length. Number of aperture blades is somewhat of a shibboleth, I think, because many lenses are used wide open to maximize selective focus, and it's in the presence of extreme selective focus that people seem to care most about bokeh. All lenses have a round aperture when used wide open.

The aperture shape affects the shape of out-of-focus specular highlights. I'm not sure it's all that visible when evaluating the general character of out-of-focus blur that doesn't have such highlights, especially if the lens renders those details with a (lovely) faded edge.

I tested the bokeh of some lenses for medium and small format, and put up a web page showing the results. The worst bokeh of the lot was displayed by an old Bausch and Lomb 139mm Tessar, which like most ancient barrel lenses has at least a dozen blades and a very round aperture.

Rick "who likes his bokeh smooooooth" Denney

[Jim Galli]

It seems to me that the bokeh "story" is quite a young one. Did anybody speak about bokeh in the beginning of the 1900s?
Beside that, if it is true what Struan says (citing Merkling) does anybody think that the old-time lens designers were after a pleasing bokeh in their lens design (not in the number of aperture leaves)?? I don't think there is any mention of it in the scientific optical literature.

Just because the japanese word had not come into favor yet doesn't mean the pictorialists from a century ago were not paying a great deal of attention. Yes, I absolutely think the lens designers were after pleasing bokeh in some of their lenses, and in particular the ones intended for portraiture. The one happy accident that set the bar so to speak was the petzval lens. They were just trying to make a lens fast enough to photograph humans and damn the rest of the shortfalls. But it took no time especially in the age of anastigmats to figure out how pleasing a petzval was for portraits.

[GPS]

...

However, while we're on the subject, will tilts and swings change the affective shape of the iris? not to mention greatly affect the lens-properties with regards to DoF affects?

They won't change the effective shape of the iris (they have no mechanical effect on them :), sorry, it's cheap, I know... ) - as to the affective shape, it's profoundly unknown to me...:)
Anyway, it will change the shape of all forms in the picture as normal tilts and swings do, it's only logical.
And the DoF effects are well known...

[Lachlan 717]

http://www.kenleegallery.com/images/tech/brasslens.jpg

Those old-time lens designers were some pretty smart physical scientists.

It seems to me that used lots of blades, because they explored and understood the issues.

Could it be that this was not an aesthetic decision, but a weight-saving one? It seems to me that the fewer blades used, the greater their required depth to cover the full aperture distance. The more blades, the thinner the required blade.

Thus, deep blades would have required a bigger housing diameter.

Given these Ol' Boys were made from brass (not alloy/plastic), this would have resulted in significant (maybe even too much to carry and/or mount) weight increases.

So, maybe this discussion about Bokeh is the tail wagging the dog?

Lachlan

[GPS]

Just because the japanese word had not come into favor yet doesn't mean the pictorialists from a century ago were not paying a great deal of attention. Yes, I absolutely think the lens designers were after pleasing bokeh in some of their lenses, and in particular the ones intended for portraiture. The one happy accident that set the bar so to speak was the petzval lens. They were just trying to make a lens fast enough to photograph humans and damn the rest of the shortfalls. But it took no time especially in the age of anastigmats to figure out how pleasing a petzval was for portraits.

Wait a moment, not so quickly..! You cannot exchange the cause for the effect. Petzval was in no way after pleasing bokeh in the design of his lens, that's obvious!
If the pictorialists were using the out of focus shapes for their artistic expression it is not yet a reason for the lens designers to go after it in their lens design. No mention of it in the scientific optics literature. That photographers could see the difference in the "bokeh" is a totally different thing from the lens design demands. I don't think there ever was any catalog tooting their lenses as those with "pleasing bokeh" or whatever the magic word could be for their lenses in the old times, suggesting that this lens was designed especially for this magic.

[Oren Grad]

I don't think there ever was any catalog tooting their lenses as those with "pleasing bokeh" or whatever the magic word could be for their lenses in the old times, suggesting that this lens was designed especially for this magic.

As David Goldfarb has pointed out previously, promotional literature for the Verito back in the 1920s made precisely such a claim:

"...a specially designed double lens... which, while it gives the desired diffused or soft optical effect, shows no distortion, double lines, or other optical imperfections, and being rectilinear gives an even diffusion over the whole plate... Will not make sharp negatives with wiry definition unless stopped down to f:8."

"Double line imperfection" is what the Japanese refer to literally as "ni-sen bokeh".

[GPS]

As David Goldfarb has pointed out previously, promotional literature for the Verito back in the 1920s made precisely such a claim:

"...a specially designed double lens... which, while it gives the desired diffused or soft optical effect, shows no distortion, double lines, or other optical imperfections, and being rectilinear gives an even diffusion over the whole plate... Will not make sharp negatives with wiry definition unless stopped down to f:8."

"Double line imperfection" is what the Japanese refer to literally as "ni-sen bokeh".

David Goldfarb where??
Soft focus = bokeh?? No distortion = bokeh? Other optical imperfections = bokeh?
Double line imperfection = bokeh as to when in the Japanese literature?? Surely not in the 1920...
Again - let's not exchange the cause for the effect, the later aesthetic criteria for the former lens design exigences.

[GPS]

As David Goldfarb has pointed out previously, promotional literature for the Verito back in the 1920s made precisely such a claim:

"...a specially designed double lens... which, while it gives the desired diffused or soft optical effect, shows no distortion, double lines, or other optical imperfections, and being rectilinear gives an even diffusion over the whole plate... Will not make sharp negatives with wiry definition unless stopped down to f:8."

"Double line imperfection" is what the Japanese refer to literally as "ni-sen bokeh".

Now, if you can come with a 1900s Japanese definition of bokeh that would be something..! For the time being, the bokeh definition is quite elusive...

[GPS]

As David Goldfarb has pointed out previously, promotional literature for the Verito back in the 1920s made precisely such a claim:

"...a specially designed double lens... which, while it gives the desired diffused or soft optical effect, shows no distortion, double lines, or other optical imperfections, and being rectilinear gives an even diffusion over the whole plate... Will not make sharp negatives with wiry definition unless stopped down to f:8."

"Double line imperfection" is what the Japanese refer to literally as "ni-sen bokeh".

Now, if for you, the "soft focus optical effect, no distortion, double lines, or other optical imperfections, and... even diffusion over the whole plate" is precisely a promotion of bokeh construction lens, for me it's even more precisely a characterization of - a soft focus lens, known to the lens designers for a long time and constructed as such. Bokeh lens design? Are all bokeh constructed lenses soft focus lenses?? Or do they have some characteristics on their own, known to the lens designers and designed especially for this "bokeh" effect?
I think what you try to sell as bokeh is something else...

[Oren Grad]

Actually, make that the 'teens - go to the Camera Eccentric website, open page 12 of the Wollensak catalog from 1912-13, and you'll find the passage from which David has quoted in earlier threads on the topic here.

The quote demonstrates that by the 1910s:

* double-line rendering, which is specifically an effect that occurs outside the plane of focus, and thus a bokeh effect, was recognized as a defect
* a particular lens design optimized for portrait use was valued in part for its ability to avoid double-line rendering
* a manufacturer had chosen to promote its product on that basis


Double line imperfection = bokeh as to when in the Japanese literature??

I don't know when the various flavors of bokeh first began to be cited as such in the Japanese literature, but it's not material to my point.

[GPS]

Actually, make that the 'teens - go to the Camera Eccentric website, open page 12 of the Wollensak catalog from 1912-13, and you'll find the passage from which David has quoted in earlier threads on the topic here.

The quote demonstrates that by the 1910s:

* double-line rendering, which is specifically an effect that occurs outside the plane of focus, and thus a bokeh effect, was recognized as a defect
* a particular lens design optimized for portrait use was valued in part for its ability to avoid double-line rendering
* a manufacturer had chosen to promote its product on that basis

I don't know when the various flavors of bokeh first began to be cited as such in the Japanese literature, but it's not material to my point.

While it is true that the double-line rendering was regarded as an imperfection the lens in question was designed as a soft focus portrait lens, not as a good bokeh lens. Again, you try to put modern aesthetic bokeh criteria on old lens design criteria.
What I say is that the characteristics the lens designers were after is a soft focus lens, not a much later Japanese bokeh elusive description. That came as a side effect.
A soft focus lens and a bokeh lens design is not the same if the bokeh mania came much much later than the desired design.
The Mediterranean diet didn't come on tables because of the modern anti cancer diet exigences.

[GPS]

Actually, make that the 'teens - go to the Camera Eccentric website, open page 12 of the Wollensak catalog from 1912-13, and you'll find the passage from which David has quoted in earlier threads on the topic here.

The quote demonstrates that by the 1910s:

* double-line rendering, which is specifically an effect that occurs outside the plane of focus, and thus a bokeh effect, was recognized as a defect
* a particular lens design optimized for portrait use was valued in part for its ability to avoid double-line rendering
* a manufacturer had chosen to promote its product on that basis



I don't know when the various flavors of bokeh first began to be cited as such in the Japanese literature, but it's not material to my point.


Do you know any old lens that is not a soft focus lens but designed so that it could avoid the "double-line rendering" thus having this desired bokeh effect?? Never heard of it in the lens design literature...

[Oren Grad]

I don't think there ever was any catalog tooting their lenses as those with "pleasing bokeh" or whatever the magic word could be for their lenses in the old times

The quote demonstrates that Wollensak did that.


suggesting that this lens was designed especially for this magic.

This part remains speculation, at least based on the evidence at hand. My sense is that, over the years, most designers, for most lenses, have optimized for performance in the plane of focus and let the OOF chips fall where they may.

In recent years among small-format lenses, there have been a handful designed specifically with bokeh in mind. The obvious examples are the 105 and 135 AF DC Nikkors, which are not soft-focus lenses; the DC ring is specifically a bokeh control. Beyond that, manufacturers have moved to more circular iris designs even in lenses with optical designs that clearly have not been optimized for pleasing bokeh.

[GPS]

The quote demonstrates that Wollensak did that.



This part remains speculation, at least based on the evidence at hand. My sense is that, over the years, most designers, for most lenses, have optimized for performance in the plane of focus and let the chips fall where they may.

In recent years among small-format lenses, there have been a handful designed specifically with bokeh in mind. The obvious examples are the 105 and 135 AF DC Nikkors, which are not soft-focus lenses; the DC ring is specifically a bokeh control. Beyond that, manufacturers have moved to more circular iris designs even in lenses with optical designs that clearly have not been optimized for pleasing bokeh.

No, Wollensak does not mention the modern pleasing bokeh. Bokeh is not the same as a soft focus lens description.

Recent lens design does not enter in the specific discussion of the old lens design. Let's not displace the discussion...
Of course, it's well known that the modern bokeh mania was used in the modern lens descriptions and designs. It has no bearing on the old lens design exigences. Romans didn't invent their diet because of today's cancer research...

[Oren Grad]

No, Wollensak does not mention the modern pleasing bokeh. Bokeh is not the same as a soft focus lens description.

The argument, simply, is that double-line rendering is necessarily a property of the out of focus part of the image, and therefore that Wollensak had to have been aware of OOF character as an attribute distinct from plane-of-focus character because they explicitly cited a phenomenon that does not appear in the plane of focus.

That's all.

[Paul Fitzgerald]

"Could it be that this was not an aesthetic decision, but a weight-saving one? It seems to me that the fewer blades used, the greater their required depth to cover the full aperture distance. The more blades, the thinner the required blade."

I doubt it, precision machining and manufacturing would off-set any material savings from the brass, AND/OR they could have expanded the aperture shell like B&L and others.

"So, maybe this discussion about Bokeh is the tail wagging the dog?"

No, the old manufacturers knew exactly what they wanted and worked for it, it's only the word 'bokeh' that's new to the scene. Read the old literature from Dallmeyer, TTH Cooke, Voightlander, Goerz, Steinheil, B&L and Wollensak.

One other thought, 'back in the day' these big dogs cost a year's salary or more, any obvious cost-cutting would not have been accepted.

[Walter Calahan]

"I dare to say, the new-time lens designers are not less smart physical scientists. They too understand the issues..."

But management tell the engineers to cut cost so they use fewer blades.

[Lachlan 717]

"Could it be that this was not an aesthetic decision, but a weight-saving one? It seems to me that the fewer blades used, the greater their required depth to cover the full aperture distance. The more blades, the thinner the required blade."

I doubt it, precision machining and manufacturing would off-set any material savings from the brass, AND/OR they could have expanded the aperture shell like B&L and others.

I think that you have missed my point. I was not talking about "material savings" per se; reduced depth of each blade allowed a reduced-diameter aperture shell, reducing weight. I am suggesting that they purposely avoided expanding the aperture shell to save weight


No, the old manufacturers knew exactly what they wanted and worked for it, it's only the word 'bokeh' that's new to the scene. Read the old literature from Dallmeyer, TTH Cooke, Voightlander, Goerz, Steinheil, B&L and Wollensak.

As I wasn't there, I am not going to be categoric in my assumption of their intent. I would hope that, unless you're 100+ years old and discussed this exact point with the lens' designers, you would not assume to know either.


One other thought, 'back in the day' these big dogs cost a year's salary or more, any obvious cost-cutting would not have been accepted.

Why not? It still happens all of the time in high end manufacturing today. Why did they go with brass? Why not gold plate it to prevent it from tarnishing? Simple: cost. Simple business theory says that you make your product as cheaply as the intended market will accept so as to maximise your margin whilst maximising your client base.

Anyway, back to the topic. Perhaps it needs to be explained why multi-bladed apertures were brought in when a Waterhouse stop can provide a near perfect circle. I have no idea. So much for Occam’s Razor…

[paulr]

As David Goldfarb has pointed out previously, promotional literature for the Verito back in the 1920s made precisely such a claim:

"...a specially designed double lens... which, while it gives the desired diffused or soft optical effect, shows no distortion, double lines, or other optical imperfections, and being rectilinear gives an even diffusion over the whole plate... Will not make sharp negatives with wiry definition unless stopped down to f:8."

"Double line imperfection" is what the Japanese refer to literally as "ni-sen bokeh".

I take it this is about a soft focus lens? I wonder if this is even the first one. It would be interesting to dig through the correspondence of people like Steichen and Stieglitz from the first decade of the 20th century.

I'm convinced from having looked at pictures and some of the literature of the era that many of the photographers were fanatics about subtle image qualities. Especially the qualities of softness. It's completely irrelevent that the Japanese word hadn't entered the vocabulary yet.

To what degree the photographers influenced optical manufacturers I can only guess. It seems like current large format lens makers put most of their attention into the in-focus parts of the image. Or if they think about bokeh, I haven't seen it mentioned in any marketing or technical literature (with the exception of Rodenstock's soft focus lens).

edited to add:
Ack! I should have read the rest of the thread. Oren found an even earlier example.
I wonder if THAT was even the first ...

[Oren Grad]

Paul, good to see you again. Whether any of the designers of what we now think of as vintage lenses consciously designed for OOF character is where all the heat is coming from this time (there's always something in a bokeh thread :)). I don't see how that can be resolved definitively without documentary evidence.

As far as OOF character as a marketing point, it's interesting to note that that passage disappears from the Wollensak catalog by 1919, so there's an interesting historical question about what they were responding to half a decade earlier, and what changed.

[Ole Tjugen]

Do you know any old lens that is not a soft focus lens but designed so that it could avoid the "double-line rendering" thus having this desired bokeh effect?? Never heard of it in the lens design literature...

The pleasing transision from sharp to unsharp as well as the smoothness of the background were very clearly emphasised in early advertisements for the Voigtländer Heliar.

I don't know what that is if it isn't bokeh.

[Struan Gray]

In my little photographic world there are two main sources of bokeh: aperture shape and aberrations.

Bright point-like objects far from the plane of focus take on the shape of the aperture. Extended objects are *convoluted* with the aperture shape, which can enhance some sort of texture. Foreground objects very close to the lens, or the blades of a leaf shutter, can change the effective shape of the aperture - a process called 'apodisation' in the literature - and further enhance or create texture.

Aberrations are a vast can of worms, but lens designers summarise them in various ways. Perhaps the most useful for bokeh enthusiasts is a 'spot diagram' which plots the spread of a point of light at the focal plane: nice spherical aberration is a smooth hatlike shape, nasty coma or astigmatism an asymmetric blob that can be quite complex. Again, non-point objects suffer convolution with these shapes, which just as with the aperture can emphasise particular directions or spatial frequencies - for example, double line bokeh is usually just bright ring bokeh from spherical aberration convoluted with a linear object.

I also include subject and camera motion blur in my own thinking about bokeh, but I know the rest of the photo universe prefers to see that as a separate effect.


Even lens designers who are not explicitly concerned with fine-tuning bokeh have to consider the tradeoffs between the various categories of aberration. Right from the start it was recognised that asymmetrical aberrations like coma and astigmatism lead to 'ugly' photographs, and the fanfares which greeted the first anastigmats were a reflection of that. Many lens designers flew by trial and error (Kingslake complains about it) but Abbe, Seidel and Petzval were well aware of how different aberrations affected different aspects of picture making, and which to control to produce an image that conformed to particular conventions of niceness.

[GPS]

In my little photographic world there are two main sources of bokeh: aperture shape and aberrations.

...
Even lens designers who are not explicitly concerned with fine-tuning bokeh have to consider the tradeoffs between the various categories of aberration. Right from the start it was recognised that asymmetrical aberrations like coma and astigmatism lead to 'ugly' photographs, and the fanfares which greeted the first anastigmats were a reflection of that. Many lens designers flew by trial and error (Kingslake complains about it) but Abbe, Seidel and Petzval were well aware of how different aberrations affected different aspects of picture making, and which to control to produce an image that conformed to particular conventions of niceness.

There is no dispute of the fact that aberrations like coma and astigmatism were of great concern to the lens designers. As Oren IMO correctly stated, these corrections were designed for the plane of focus where they played the main role. The fact that these corrections had an affect on the OOF areas too is a simple additional effect. The optical design literature doesn't mention any old design that strives primarily for OOF bokeh qualities as the main reason for such design.
The advertisement mentioned by Ole is a different thing than a purposeful lens design striving for bokeh qualities.
As for the number of aperture blades, with no access to my library I cannot dig it out but isn't it mentioned somewhere (Ray??) that it had more to do with the huge lens diameters of portrait lenses? IIRC we've discussed it already...

[GPS]

...

Many lens designers flew by trial and error (Kingslake complains about it) but Abbe, Seidel and Petzval were well aware of how different aberrations affected different aspects of picture making, and which to control to produce an image that conformed to particular conventions of niceness.

While I wholeheartedly agree with you that Petzval (my technical hero from my age of 10 years :) ) was well aware of the optical aberrations in lens designs it doesn't imply that his portrait lens was designed for some pleasing circular swirl of OOF areas, that would be an incorrectly stretched out statement. His primary concern, mentioned in lens design handbooks, was a greater speed of portrait lenses and a better aberration correction in the center of the field of view. Again, the swirl came as a side effect. Even in his time it wasn't any niceness to strive for (see the following lens design development where this niceness, so appreciated by modern aficionados, disappeared without any tears on the lens designers faces...:))

[GPS]

"I dare to say, the new-time lens designers are not less smart physical scientists. They too understand the issues..."

But management tell the engineers to cut cost so they use fewer blades.

As a theory for the reason of a smaller number of aperture blades it is original but little convincing in lenses that cost $$$$...:)

[Arne Croell]

Anyway, back to the topic. Perhaps it needs to be explained why multi-bladed apertures were brought in when a Waterhouse stop can provide a near perfect circle. I have no idea. So much for Occam’s Razor…

I think thats easy.
1. Most waterhouse stop sets come in full stop increments. Since many shutters work in full stop increments, your exposure control would be limited to full stop changes.
2. For a lens with the aperture going from f/5.6 to f/45, you need 6 waterhouse stops. For each lens you need a new set, since its the diameter of the entrance pupil that counts, not the physical diameter of the stop. So for three lenses you'd end up with 18 stops. How easy is it to loose any of those?!

[mrpengun]

I think thats easy.
1. Most waterhouse stop sets come in full stop increments. Since many shutters work in full stop increments, your exposure control would be limited to full stop changes.
2. For a lens with the aperture going from f/5.6 to f/45, you need 6 waterhouse stops. For each lens you need a new set, since its the diameter of the entrance pupil that counts, not the physical diameter of the stop. So for three lenses you'd end up with 18 stops. How easy is it to loose any of those?!

Just as easy as it would be to make an unrepairable mistake during the wet-plate process :-)

Although in seriousness, it is also important to consider the early market for lenses as well. Sometimes I feel we try to apply our contemporary consumer models onto previous generations-- Any new lens design would have to be advertised in a journal with a very small print run. Market penetration would thus be very small, particularly if it was not championed by someone who is now viewed in terms of the photographic canon.
This is not to say that a waterhouse design did not have its benefits or flaws, just that mid 19th century market acceptance was likely a large contributing factor in what we now view as "good" lens design.

[Ken Lee]

To settle the question, we're going to have an on-line séance (http://en.wikipedia.org/wiki/Séance). That's right: We need to make direct contact with some of the lens designers who worked 100 years ago. Let's hope they are willing to divulge their secrets ;)

[jnantz]

sorry to be slightly off topic
but has anyone here used the star apertures that were advertised with the veritos?
they seem to be the wollensak-take on the imagon's sink-strainer

photographers often used the verito as an enlarging optic as well as a camera lens,
is that when the star aperture was used?

thanks

john

[Struan Gray]

No need for a séance, here's the word from the horse's mouth:

http://books.google.co.uk/books?id=ALUaAAAAYAAJ

From a paper by J.T. Taylor (p260): "The qualifications of a good portrait lens are, that it shall have a large angular aperture; be composed of glass of uniform density and such a colour as to obstruct as few of the actinic rays as possible; have its chromatic and spherical aberrations reduced to a minimum, combined with the maximum of flatness of field."

There are also papers and letters by Dallmeyer, Sutton and others on the design of lenses and their motivations during the design process. Also a series of papers by Goddard on aberrations (search on 'oblique pencil') and their effects.

At this point - 1860-ish - the the emphasis was on developing tools to make photography more true to life. Faster lenses for 'instantaneous' photographs, and distortion and swirly-free lenses for landscapes. There were still no true anastigmats at this point, in fact introducing a little astigmatism was a standard way of flattening the field. Squelching both astigmatism and field curvature required the new glasses introduced by Schott in the late 1880s.

That said, in the mid 1860s or so if I remember rightly, Julia Margaret Cameron's portraits effected a revolution, and then you started to get photographs being praised for their 'plastic' qualities. The plastic qualities of *lenses* seem to be advanced as a virtue only later, in the 1880s and 1890s, when all-over sharpness had become a relatively simple technical matter and there was something to react against.

A. Horsely-Hinton's article on 'Pictorial Photography' tacked onto the photography entry in the 1911 Encyclopedia Britannica has a brief discussion of the movement's history, and tends to emphasise developments in plates and printing papers - the improvement of lenses being seen as an obstacle. See: http://www.1911encyclopedia.org/Photography

[GPS]

No need for a séance, here's the word from the horse's mouth:

http://books.google.co.uk/books?id=ALUaAAAAYAAJ

From a paper by J.T. Taylor (p260): "The qualifications of a good portrait lens are, that it shall have a large angular aperture; be composed of glass of uniform density and such a colour as to obstruct as few of the actinic rays as possible; have its chromatic and spherical aberrations reduced to a minimum, combined with the maximum of flatness of field."

There are also papers and letters by Dallmeyer, Sutton and others on the design of lenses and their motivations during the design process. Also a series of papers by Goddard on aberrations (search on 'oblique pencil') and their effects.
...


In other words, the magic bokeh is nowhere mentioned at all as a prerogative for a special portrait lens design.
Optical aberrations were always on mind of lens designers but they are not equivalent to bokeh qualities.
That bokeh magic then, in whatever terms, was a concern to a few already in the old times (as it is today) is sure without any doubt. But bokeh considerations as a lens designer purpose in designing a special lens with a given bokeh magic is not mentioned in the history of a lens design, not for old lenses. It was a side effect of a lens design, commented on and used or not by people who noticed that.

[Jim Galli]

In other words, the magic bokeh is nowhere mentioned at all as a prerogative for a special portrait lens design.
Optical aberrations were always on mind of lens designers but they are not equivalent to bokeh qualities.
That bokeh magic then, in whatever terms, was a concern to a few already in the old times (as it is today) is sure without any doubt. But bokeh considerations as a lens designer purpose in designing a special lens with a given bokeh magic is not mentioned in the history of a lens design, not for old lenses. It was a side effect of a lens design, commented on and used or not by people who noticed that.

Try to obtain a copy of Jay Allens book Pictorial Soft Focus and Portrait Lenses. It is mostly a compilation of original sales literature released at the same time as the lenses. Almost every manufacture starting at the top with Bausch & Lomb to Zeiss Jena Tessar at the bottom has wording trying to describe pleasing out of focus area quality without using an obscure japanese word that would come along 90 years later on the internet.

This idea is nothing new. John the apostle in visions around 96 AD saw what we now believe is probably describing the atom bomb. That word wasn't in vogue and he called it "fire and brimstone and vapor of smoke". I think you're too hung up on the word bokeh. Good for the japanese for giving it to us but it doesn't need to confine beautiful out of focus area to the last 5 years. That has existed as long as there were lenses. Did you know the japanese were taking the achromatic meniscus lenses out of their Kodaks in 1917 and using them wide open to achieve soft focus?

[Paul Fitzgerald]

"Anyway, back to the topic. Perhaps it needs to be explained why multi-bladed apertures were brought in when a Waterhouse stop can provide a near perfect circle. I have no idea. So much for Occam’s Razor…"

As was mentioned, people would lose the inserts SO someone invented wheel stops BUT this still left an open slot in the lens for dirt and grime to enter SO someone invented the internal iris aperture.

The mega-blade iris aperture is the most expensive answer to the problem, the observation between even and odd number of blade arose and compounded the expense. So why was it used by all manufacters? Rather damn simple, it's the best answer for the situation:

1) stopping down with an iris is watching a movie, stopping down with Waterhouse tabs or wheel stops is an eye exam, it just doesn't work well.
2) the 'bokeh' of a lens changes at 1/3 stop increments, way too many Waterhouse tabs or too large of a wheel to be useful (yes, they knew that a century ago)

"But bokeh considerations as a lens designer purpose in designing a special lens with a given bokeh magic is not mentioned in the history of a lens design, not for old lenses."

So why did Wollensak come out with the 'Varium' lenses in 1926? They already had Velostigmat, Vitax, Verito, Vesta, and Volta, each with their own distinct and different signiture.

[Struan Gray]

In other words, the magic bokeh is nowhere mentioned at all as a prerogative for a special portrait lens design.
Optical aberrations were always on mind of lens designers but they are not equivalent to bokeh qualities.
That bokeh magic then, in whatever terms, was a concern to a few already in the old times (as it is today) is sure without any doubt. But bokeh considerations as a lens designer purpose in designing a special lens with a given bokeh magic is not mentioned in the history of a lens design, not for old lenses. It was a side effect of a lens design, commented on and used or not by people who noticed that.

How old is old?

My point was that one hundred and fifty years ago it was not an explicit issue for lens designers, but by a mere hundred years ago it was. The Edwardian pictorialists, and the later C20th movements in the 20s and 30s, were acutely aware of the way lenses rendered out-of-focus areas.

A UK site last year put up trial copies of The Studio and a couple of equivalent European publications. Unfortunately it seems to have died before it really got started. The discussions of photography and of photographers like Perschied and J.Craig Annan in their pages make it quite clear that out-of-focus rendering is of high importance, and that specialist lenses should be used for best efffects. Those with access to 'good libraries' can find them in paper form.

[GPS]

Again Jim, advertisement of certain side effects of a lens design and a purposeful lens design are two entirely different things. Nobody disputes the fact that photographers were aware of different OOF lens qualities. But you cannot use this fact as a proof of purposeful lens design on the lens designer side (speaking the old timers). They were concerned with the focused field properties, there their calculating efforts went. The rest was a side effect.
You still don't discern the cause and the effect.

[cowanw]

But bokeh considerations as a lens designer purpose in designing a special lens with a given bokeh magic is not mentioned in the history of a lens design, not for old lenses. It was a side effect of a lens design, commented on and used or not by people who noticed that.

I expect that lens marketers were just as savy then. If people were buying their lenses based on a side effect then you can be sure the next ad that came out touted that effect. Vis a Vis the verito ad
To put the emphasis on another syllable, and a bit of the onus on you, GPS, are there any modern ads that say "We have designed this lens to have the best bokeh!"?
A brief search off the Linos and Schneider sites did not come up with a mention of Bokeh
Regards
Bill

[GPS]

How old is old?

My point was that one hundred and fifty years ago it was not an explicit issue for lens designers, but by a mere hundred years ago it was. The Edwardian pictorialists, and the later C20th movements in the 20s and 30s, were acutely aware of the way lenses rendered out-of-focus areas.

....

Listen again, man. The fact that photographers were aware of the different OOF qualities has nothing to do with the purpose of lens designers when creating a lens, speaking the old time (i.e. up to the modern time special effect lenses).
Lens designers calculated their lenses for the in the focus areas and the OOF area was a side effect. Nobody was calculating the other way round! Why not? Well, the OOF bokeh has no scientific definition, just aesthetic consideration.
You try to rewrite the lens design handbooks...

[Jim Galli]

You try to rewrite the lens design handbooks...

But you were there?? You sure seem to be in the brains of every lens designer from Petzval to Kingslake. How did you accomplish that?? Your knowledge of their very thoughts is impressive.

[GPS]

I expect that lens marketers were just as savy then. If people were buying their lenses based on a side effect then you can be sure the next ad that came out touted that effect. Vis a Vis the verito ad
To put the emphasis on another syllable, and a bit of the onus on you, GPS, are there any modern ads that say "We have designed this lens to have the best bokeh!"?
A brief search off the Linos and Schneider sites did not come up with a mention of Bokeh
Regards
Bill

Bill, let's not be going in circles. As already said, i don't think that soft focus lenses are an example of a special bokeh designed lens. Unless you want to nail the magic bokeh to a soft focus beast...
Oren (?) gave examples of some modern lens design for 35mm photography made primarily with bokeh in mind. I don't know them.

[GPS]

A question for the savvy ones among us - how do you express the bokeh niceness in scientific terms and aberration values so that you could use it in the lens design calculations purposely aimed at the creation of a lens with "pleasing bokeh"?

[GPS]

"...
So why did Wollensak come out with the 'Varium' lenses in 1926? They already had Velostigmat, Vitax, Verito, Vesta, and Volta, each with their own distinct and different signiture.

Once again, you are speaking soft focus lenses. Bokeh is the same as a soft focus for you?

[GPS]

But you were there?? You sure seem to be in the brains of every lens designer from Petzval to Kingslake. How did you accomplish that?? Your knowledge of their very thoughts is impressive.

That's not a clever comment, Jim.
Unlike you, I'm not trying to rewrite the lens design history books. I just logically follow it - enough books about it.
Now, do you know the famous optical designer that calculated his lens purposefully for "nice bokeh" as a result? What aberration criteria did he use for the elusive beast? I wonder...
"In the 1900s Zeiss came with the famous Bokehar lens, calculated specially for pleasing bokeh by the renown optical engineer Rudolph Cucumber."
If only I knew where in the lens design history books it was written...:)

[Oren Grad]

Oren (?) gave examples of some modern lens design for 35mm photography made primarily with bokeh in mind. I don't know them.

AF DC-Nikkor 105mm f/2D (http://www.nikonusa.com/Find-Your-Nikon/Product/Camera-Lenses/1932/AF-DC-NIKKOR-105mm-f%252F2D.html)

AF DC-Nikkor 135mm f/2D (http://www.nikonusa.com/Find-Your-Nikon/Product/Camera-Lenses/1935/AF-DC-NIKKOR-135mm-f%252F2D.html)

Minolta/Sony 135mm f/2.8[T/4.5] STF (http://www.sonystyle.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10551&storeId=10151&langId=-1&productId=11040530)

[goamules]

In the interest of this discussion I have a few questions for GPS and the others to consider.

1. Would you say any lens has nice bokeh at small aperatures, like f64 or f128?


2. Do we agree that lens designers worked for some attributes like speed, sharpness/softness, flat field, anastigmatism?

Garrett

[GPS]

I don't believe in any scientific criteria of bokeh niceness, sorry.
Ad.2 - surely they did.

[GPS]

...
This idea is nothing new. John the apostle in visions around 96 AD saw what we now believe is probably describing the atom bomb. That word wasn't in vogue and he called it "fire and brimstone and vapor of smoke". I think you're too hung up on the word bokeh. Good for the japanese for giving it to us but it doesn't need to confine beautiful out of focus area to the last 5 years. That has existed as long as there were lenses. Did you know the japanese were taking the achromatic meniscus lenses out of their Kodaks in 1917 and using them wide open to achieve soft focus?

You know that religion is forbidden to discuss on this forum... Your exegesis seems out of place here.
As for you definition of bokeh - it is difficult to state that there were optical designs calculated specifically for nice bokeh when at the same time you don't know what that word stands exactly for... Now who really hangs on that bokeh...:)

[goamules]

Well I think I agree with you.

Would you say lens designs were tested in prototype, after mathmatical design?

Since (if) there is no quantitative parameters of OOF "beauty or goodness", do you then think some of the attributes were discovered or verified during prototype testing?

Garrett

[Jim Galli]

None of us were there 100 120 150 years ago when many of the designs were laid out. I'm old, but I'm not that old. All we can do is make some intuitive educated guesses. A couple of examples where bokeh was the intent although the word was not used might be the Derogy Anachromatique, the Busch Nicola Perscheid, and the Pinkham Semi Achromatic's. In each of these lenses the word 'suggested' comes to play. Puyo suggested the design of two simple menisci facing each other to the lens maker Derogy and the name of the lens is all the proof you need of the intent. Anachromatique means exactly what it says. They purposely made a lens that has chromatic abberation so that the end result will be a soft pleasing portrait. Holland Day brought this idea to America and suggested to his friend Henry Smith a lens that did not completely correct chromatic aberation for the purpose of non-harshness. Pinkham and Smith built the SA series of lenses. Nicola Perscheid suggested to Busch a design where the corrections of the currently popular f8 Aplanat be throttled back and the aperture increased to f4 and Busch built the Nicola Perscheid lens. In every case the purpose was to move in a different direction with purpose from the dazzlingly sharp anastigmats. These are just 3 of likely very many. I believe intuitively but have no proof that this was very much a seat of the pants process. Like, hmmm, lets tweak this and see what we get.

Finally, the example of Wollensak has already come up. The subjective quality of the different lenses and what they do is so much a matter of individual taste that you have someone like Wollensak making more lens lines than General Motors made car lines. Everybody likes something different and it really is unquantifiable. So Wolly covered all the bases, as did Gundlach and Dallmeyer and others. Tired of the Chevy, move up to a Buick.

I think what we're really fussing over is the term I introduced, unquantifiable. Our modern scientific minds struggle with that idea. I am in fact a rocket scientist. I work for Sandia National Labs. I have no problem what-so-ever understanding that if you have 10,000 different people saying 10,000 different things that must be present in the formulae for what really is perfect bokeh........the best solution is to admit, it is unquantifiable. Still, you other scientists out there, have at it.

[Jim Galli]

You know that religion is forbidden to discuss on this forum... Your exegesis seems out of place here.
As for you definition of bokeh - it is difficult to state that there were optical designs calculated specifically for nice bokeh when at the same time you don't know what that word stands exactly for... Now who really hangs on that bokeh...:)


Go and study the incidents surrounding my signature I always use on this forum and perhaps you can have me banned for good sir.

[goamules]

Jim, that's where I was going too; that mathmatical lens designs still had to be prototyped, demonstrated and tested. If GPS agrees that some attributes were not able to be mathmatically designed.

So now we are getting to a chicken or egg question. Do lens designers create a new attribute and hand it to users on a silver platter, explaining what it's good for? Or do users discover, discuss and accentuate a "side effect", causing lens designers to either alter a design, or at least advertise the effect?

[Oren Grad]

1. Would you say any lens has nice bokeh at small aperatures, like f64 or f128?

No. If the subject configuration allows for a substantial OOF area at the set aperture, the character will still vary across different designs.

[Oren Grad]

I don't believe in any scientific criteria of bokeh niceness, sorry.
Ad.2 - surely they did.

The fact that there's no quantitative measure of bokeh does not prevent designing for it, if that's what you want. Even those designers whose concern is to optimize at the plane of focus make differerent qualitative tradeoffs among performance parameters to achieve the desired overall effect. There's no single figure of quantitative merit that unambiguously characterizes goodness in lens performance.

[Ken Lee]

It's not unreasonable to guess that like Teflon (http://en.wikipedia.org/wiki/Teflon) and Penicillin (http://en.wikipedia.org/wiki/Penicillin), some advances in Optics have been made due to... "providence". Once recognized as desirable, they were subsequently refined, named, and even marketed.

To prove for certain whether this or that optical effect was developed after an intentional search, or discovered through sheer accident (or a bit of both as I suspect in this case) may prove a "fool's errand".

[GPS]

Go and study the incidents surrounding my signature I always use on this forum and perhaps you can have me banned for good sir.

What has that to do with a lens designed for bokeh? I'm not interested in a shouting match with you - go and shout for yourself.

[GPS]

The fact that there's no quantitative measure of bokeh does not prevent designing for it, if that's what you want. Even those designers whose concern is to optimize at the plane of focus make differerent qualitative tradeoffs among performance parameters to achieve the desired overall effect. There's no single figure of quantitative merit that unambiguously characterizes goodness in lens performance.

Yes, they make trade offs to achieve the desired effect - on the plane of focus.
But how do you want to calculate for something like pleasant bokeh? You make a lens and look at its bokeh? If it pleases you not you change what parameter? Common...

[GPS]

I'm quite surprised what emotions this thread arouses.
Now, to make it more to the point - whoever knows there is a lens specially and primarily calculated for nice bokeh, come out and say its name, the designer and its story. After all, it can be more interesting than whatever else in the debate...

[GPS]

Jim, that's where I was going too; that mathmatical lens designs still had to be prototyped, demonstrated and tested. If GPS agrees that some attributes were not able to be mathematically designed.

So now we are getting to a chicken or egg question. Do lens designers create a new attribute and hand it to users on a silver platter, explaining what it's good for? Or do users discover, discuss and accentuate a "side effect", causing lens designers to either alter a design, or at least advertise the effect?

How on Earth you calculate a lens design for an attribute that cannot be mathematically designed?? :rolleyes: :)

[goamules]

But we've already addressed "...specially and primarily calculated for nice bokeh..." There probably isn't one primarily designed for that, just as there isn't one primarily designed for light weight. It isn't that black and white. I thought the question was did the designers consider OOF attributes in their designs?

[Oren Grad]

Yes, they make trade offs to achieve the desired effect - on the plane of focus.
But how do you want to calculate for something like pleasant bokeh? You make a lens and look at its bokeh? If it pleases you not you change what parameter? Common...

How do you calculate for a pleasant rendering in the plane of focus? If it pleases you not you change what parameter?

[GPS]

How do you calculate for a pleasant rendering in the plane of focus? If it pleases you not you change what parameter?

A pleasant rendering in the plane of focus is the chosen value of aberrations you desire. If it pleases you not you either change the aberration values or the lens design. For both there are mathematical rules.
But how do you calculate it when something pleasant doesn't have any scientific values to be expressed in..? You pray to Penicillin or worship the Lady Optical Providence?

[rdenney]

I know that this discussion is annoying some of you, but as a new member it includes many aspects I've not heard before and I appreciate it.

I don't think it matters except as a point of historical interest whether lens designers explicitly targeted bokeh in their designs or not. And I think that even if they did, it got no more consideration than their other objectives, including distortion, flatness, evenness, correction of aberrations, and so on.

But that doesn't mean their results don't have artistic consequences that we modern anachronists may choose to pursue.

I go back to the post describing the illumination across the disk that is an out-of-focus projection of a specular highlight in the scene. It seems that lenses with a hair of undercorrected spherical aberration render these disks with a faded edge. I offer the Zeiss Olympia Sonnar as an example. The most recent version of that lens is the 180/2.8 Zeiss Jena Sonnar, produced in the Pentacon Six mount up until 1991 or so. That lens is very sharp stopped down, and has an underlying sharpness even wide open, but loses contrast because of that aberration. As one stops that lens down, the effect of the aberration diminishes at about the same rate as the shrinking of those out-of-focus highlights, or so it seems to me. Some lenses that are good wide open aren't as good a few stops down, and some that are good a few stops down produce a downright surreal pattern when used wide open. And then there's the difference in the effect in the macro range versus at longer distances, and the difference of the effect whether the out-of-focus detail is in front of or behind the focus plane. The combinations and permutations of such effects are probably beyond ancient design models and methods.

More importantly, some photographers like those swirly artifacts, and others prefer the smooth look of the faded edge. Quantifying bokeh is one thing--evaluating it in terms of good and band is another thing altogether. Every effect has its admirers and detractors, and it's up to their photographs to state the case.

Thank you all for the discussion--it has been most enlightening. I have pursued this topic quite a lot with medium and small format lenses, but the discussions surrounding it in the large-format domain, while seemingly no less heated, are of a much higher order.

Rick "learning lots" Denney

[GPS]

It's not unreasonable to guess that like Teflon (http://en.wikipedia.org/wiki/Teflon) and Penicillin (http://en.wikipedia.org/wiki/Penicillin), some advances in Optics have been made due to... "providence". Once recognized as desirable, they were subsequently refined, named, and even marketed.

To prove for certain whether this or that optical effect was developed after an intentional search, or discovered through sheer accident (or a bit of both as I suspect in this case) may prove a "fool's errand".

First the séance, then Penicillin, providence... Do you know the answer to the post #68? :)

[Oren Grad]

A pleasant rendering in the plane of focus is the chosen value of aberrations you desire. If it pleases you not you either change the aberration values or the lens design. For both there are mathematical rules.
But how do you calculate it when something pleasant doesn't have any scientific values to be expressed in..? You pray to Penicillin or worship the Lady Optical Providence?

You do it exactly the same way. You know from experience what the visual effect of different aberrations is, and you choose your mix to suit.

The AF DC Nikkors and the Minolta STF exist. They were designed somehow.

[GPS]

You do it exactly the same way. You know from experience what the visual effect of different aberrations is, and you choose your mix to suit.

The AF DC Nikkors and the Minolta STF exist. They were designed somehow.

You cannot do it "exactly the same way" because you don't have quantitative values to work with in the first place.
The AF Nikkors text speaks about background's spherical aberration. Is it the same thing as bokeh?

How about Kingsley? Does he mention pleasant bokeh lens design somewhere? Common, don't be shy, show it...:) I know, the mythical Bokehar from the 1900s - if only the big water didn't take the plans...

[Oren Grad]

The AF Nikkors text speaks about background's spherical aberration. Is it the same thing as bokeh?

Did you read Harold's article?

[goamules]

It may not be quantitative, but we surmise good bokeh is a factor of:

Round aperture (designed for "mid stop" ability and user convenience)
Softness (designed to prevent wiry sharpness)
Wide apertures (designed for speed)
etc....

I think many of these "designed" features had other results in prototype that the designers liked. The in focus, the out of focus, the weight, all were reviewed. Perhaps they then chose to produce such a design. Just as early humans domesticated the more succulent fruit by picking and eating it, the "best" lens designs were produced. Many inventions follow this idea of designing for one thing, then noticing another feature.

[GPS]

It may not be quantitative, but we surmise good bokeh is a factor of:

Round aperture (designed for "mid stop" ability and user convenience)
Softness (designed to prevent wiry sharpness)
Wide apertures (designed for speed)
etc....

I think many of these "designed" features had other results in prototype that the designers liked. The in focus, the out of focus, the weight, all were reviewed. Perhaps they then chose to produce such a design. Just as early humans domesticated the more succulent fruit by picking and eating it, the "best" lens designs were produced. Many inventions follow this idea of designing for one thing, then noticing another feature.

In other words, the magical bokeh is a side effect of a lens design calculated primarily for the in focus plane. I agree. Some of the lenses, calculated in this way produce bokeh that for some people is pleasing while others couldn't care less. It would be a heck of a lens calculating for something that is so vaguely defined as round aperture, softness, wide apertures etc...
When the dust settles down, we'll have the classical Bokehar named and the story behind its design school told. Then we can think again in clear terms...:) Up to then, I think I'll sleep calmly.

[GPS]

Did you read Harold's article?

Do you read Bible?:) Leave the poor guy in peace and reveal the mythical Bokehar instead... Yawn:)

[jnantz]

So why did Wollensak come out with the 'Varium' lenses in 1926? They already had Velostigmat, Vitax, Verito, Vesta, and Volta, each with their own distinct and different signiture.


paul

i think it is because they paid some guy in the back room
to come up with as many V words as he could for a few months
and since they were paying him for his work, they had to come up
with another lens ... they also modified the verito and came up with the veritar
a handful of years later as well ...

[cowanw]

Not large format but specifically designed for bokah
http://www.dyxum.com/columns/articles/lenses/SAL-135F28/Sony-AF-135-STF-SAL-135F28_review.asp
And there must be a definition now because there is an alien skins computer program to mimic it:rolleyes:
Regards
Bill

[GPS]

But we've already addressed "...specially and primarily calculated for nice bokeh..." There probably isn't one primarily designed for that, just as there isn't one primarily designed for light weight. It isn't that black and white. I thought the question was did the designers consider OOF attributes in their designs?

I agree that there isn't a lens primarily designed for the pleasant bokeh, you know that. That was the question.
As for the other statement - surely they did - as a side effect of their primary optical considerations, they could see the results. But no optical fool known in the history of a lens design went so far as to hunt the proverbial pleasant bokeh as the primary optical requirement for his lens. Or - maybe the Bokehar really exists...?:)
Cheers!

[Oren Grad]

Do you read Bible?:) Leave the poor guy in peace and reveal the mythical Bokehar instead... Yawn:)

Here's chapter 1 of the Book of the Bokehar:

http://www.the135stf.net/apodisation.html

[goamules]

It would be a heck of a lens calculating for something that is so vaguely defined as round aperture, softness, wide apertures etc...

Well, not exactly defined as that. These are just some physical things besides glass design that contribute to what everyone agrees is subjective. Yet, the Japanese have better descriptions, including "bad" double line bokeh. Which 1920s Wollensak literature called "bad" double line (something). Seems to be the same symptoms but different terms.

Also - the designers did apply their calculations to "optimize" (another subjective scale that was tested in prototype demonstrations) spherical aberrations, coma, etc. These attributes also contribute greatly to bokeh.

Did anyone a hundred years ago discuss bokeh? Absolutely. Did designers listen? You can guess, or we can keep piling the evidence on.

About 1911 Coburn quoted George Bernard Shaw’s observation on bokeh: “You
have no more of what Bernard Shaw calls one of 'the infuriating academicisms of
photography,' one plane of the picture sharp and all the others wooly and unnatural, a
thing that no self-respecting human eye would ever see.”Coburn clearly identifies the out of focus areas as “wooly and unnatural,” terms that would have meaning to almost any advanced photographer, and perfectly describes one form of bad bokeh. Also writing in 1911, Anderson vividly describes unpleasant bokeh as “when out-of-focus leaves and branches seem to assume unusual shapes, when the light which shines through the branches is converted into round bull's-eyes, the work becomes contrary to the spirit of impressionism.”The Japanese identify this as “doughnut” or “ring” bokeh and consider it one of the least desirable forms. (THE SOFT-FOCUS LENS AND ANGLO-AMERICAN PICTORIALISM, Thesis of William Russell Young, III)

GPS, just because something is hard to put your finger on, doesn't mean it's not there. But we're not talking religion here.

[Oren Grad]

And here's chapter 2 of the Book of the Bokehar:

http://imaging.nikon.com/products/imaging/technology/nikkor/n32_e.htm

[cowanw]

I'm quite surprised what emotions this thread arouses.
Now, to make it more to the point - whoever knows there is a lens specially and primarily calculated for nice bokeh, come out and say its name, the designer and its story. After all, it can be more interesting than whatever else in the debate...

Surprised, but not so dismayed to take it to another thread.
Bill

[GPS]

Not large format but specifically designed for bokah
http://www.dyxum.com/columns/articles/lenses/SAL-135F28/Sony-AF-135-STF-SAL-135F28_review.asp
And there must be a definition now because there is an alien skins computer program to mimic it:rolleyes:
Regards
Bill

Ha ha, I wonder why they used the special a-something element when there was already a whole design school (some of us believe it existed already at the beginning of 1900s...) that achieved the same with simple lens elements... I think they didn't read Kingsley... Or didn't know Penicillin, or whatever...
Seriously - what it is all about is a special effect lens. You would probably have a crowd of people who would say it is not the mythical pleasant bokeh they like as there isn't any consensus for good bokeh in this miserable world yet and that it is not the Bokehar they are after...
If this is the bokeh you want, good for you. As for the whole discussion, we were talking - remember that? - old lens designs...
Nevertheless, those happy among us have something to ask Schneider for in this century. High time we had our Bokehar too, isn't it? Cheers!

[GPS]

Well, not exactly defined as that. These are just some physical things besides glass design that contribute to what everyone agrees is subjective. Yet, the Japanese have better descriptions, including "bad" double line bokeh. Which 1920s Wollensak literature called "bad" double line (something). Seems to be the same symptoms but different terms.

Also - the designers did apply their calculations to "optimize" (another subjective scale that was tested in prototype demonstrations) spherical aberrations, coma, etc. These attributes also contribute greatly to bokeh.

Did anyone a hundred years ago discuss bokeh? Absolutely. Did designers listen? You can guess, or we can keep piling the evidence on.

About 1911 Coburn quoted George Bernard Shaw’s observation on bokeh: “You
have no more of what Bernard Shaw calls one of 'the infuriating academicisms of
photography,' one plane of the picture sharp and all the others wooly and unnatural, a
thing that no self-respecting human eye would ever see.”Coburn clearly identifies the out of focus areas as “wooly and unnatural,” terms that would have meaning to almost any advanced photographer, and perfectly describes one form of bad bokeh. Also writing in 1911, Anderson vividly describes unpleasant bokeh as “when out-of-focus leaves and branches seem to assume unusual shapes, when the light which shines through the branches is converted into round bull's-eyes, the work becomes contrary to the spirit of impressionism.”The Japanese identify this as “doughnut” or “ring” bokeh and consider it one of the least desirable forms. (THE SOFT-FOCUS LENS AND ANGLO-AMERICAN PICTORIALISM, Thesis of William Russell Young, III)

GPS, just because something is hard to put your finger on, doesn't mean it's not there. But we're not talking religion here.

A nice try. Now go the the sqaure one and find what exactly is the disputed fact. Not a fact that bokeh was spoken about by the old masters...
Take your time, not mine.

[GPS]

And here's chapter 2 of the Book of the Bokehar:

http://imaging.nikon.com/products/imaging/technology/nikkor/n32_e.htm

A nice try for you too, Oren...:) Remember the original topic of this dispute? Go back to the square one, your Bokehar is a fake, doesn't qualify... :) Cheers!

[GPS]

Surprised, but not so dismayed to take it to another thread.
Bill

??? Short memory problem?

[Eric James]

...:) ... :) Cheers!

You seem to be in such a great mood - maybe today is the day you'll show us one of your moon pictures.

[Jim Galli]

You seem to be in such a great mood - maybe today is the day you'll show us one of your moon pictures.

:) Actually, I think he's been mooning us for several pages. :)

:) :)

[Eric James]

I saw that coming :)

[Oren Grad]

A nice try for you too, Oren...:) Remember the original topic of this dispute? Go back to the square one, your Bokehar is a fake, doesn't qualify... :) Cheers!

You have repeatedly questioned how it is even possible to design for bokeh, then or now. Between the AF DC and the STF, we've given you two answers, with documentation to support.

[goamules]

...find what exactly is the disputed fact. Not a fact that bokeh was spoken about...


It seems to me that the bokeh "story" is quite a young one. Did anybody speak about bokeh in the beginning of the 1900s?
...does anybody think that the old-time lens designers were after a pleasing bokeh in their lens design (not in the number of aperture leaves)?? I don't think there is any mention of it in the scientific optical literature. (GPS post #10)

Then why did you bring up that it wasn't discussed in the day? Maybe it wasn't in this tread, but your other one Re: Bokeh. Anyway, if the real question is "Did lens designers consider bokeh and design for/against it...I say yes. You have started stating the question as "Did designers primarily design for bokeh" which I don't think anyone is saying. So you are wrong, they did. But you are right, they didn't. Probably...I'm going back to work.

[jb7]

Remember the original topic of this dispute?


It really doesn't seem to matter-
the arguments are yours, the original topic of this thread has been long sidestepped,
and only your own agenda is at work.

Apparently, the original topic was about stopping down, and aperture blades,
and the effect it might have on the rendition of out of focus areas,
insofar as I could decipher it.

Lens design wasn't mentioned in the original proposition.

The strange thing is, you probably like images to be uniformly sharp,
and find the idea of blur unsettling...
Although I really have no idea, not having seen any of your images.

I feel sorry for you, to find yourself surrounded by so many amateurs,
who are clearly so many levels below you-


joseph

[Struan Gray]

A couple of points.

First, it is *not* difficult to quantify bokeh. Lens design programs do it routinely. As I mentioned in an earlier post, most will generate spot diagrams for different parts of the focal plane and different focussing distances. If you don't have a physicist's ability to do do convolutions in your head, some programs will generate synthetic images so you can see the effects on 'real' images.

The difficult thing is to come up with an agreed sense of what constitutes 'good' bokeh. Once you have done that, designers will make you a lens with the right package of aberrations - how close they come depends on how much you are prepared to pay.

GPS, you seem to be under the illusion that soft focus lenses are designed with only the focal plane in mind. I must confess it took me a while to realise this was what your needling was meant to convey. Perhaps the best evidence that the background was important too is the widespread use of undercorrected spherical aberration in these lenses.

Some classical soft focus lenses use chromatic aberrations, but from Dallmeyer to the latest über-Cooke the most usual method was to add a selected - or adjustable - amount of spherical aberration. The interesting thing is that they all add *undercorrected* spherical aberration.

When focussed on infinity, undercorrected spherical aberration gives you that nice central blob surrounded by a fuzzy halo. Overcorrected spherical aberration gives you the nasty bright ring with a dimmer core. At closer focussing distances things get more interesting. The blur switches from one type to the other as you pass through the plane of focus. This means you can get your lovely blob-and-halo at the focal plane from either undercorrected or overcorrected spherical aberration, provided you adjust the exact position of focus appropriately. The only reason to prefer a lens which is undercorrected is that it ensures that the background gets a nice-looking blob-and-halo too.

I'll see if I can find a last nail for the coffin when I'm at my desk and can access journals and JSTOR without having to pay. It seems pretty firmly closed to me already though.

[GPS]

You have repeatedly questioned how it is even possible to design for bokeh, then or now. Between the AF DC and the STF, we've given you two answers, with documentation to support.

No, my dear, I'm sorry. Your documentation is for a spherical aberration. Remember, I gave you a question (a poisonous one, bad me...:) ) if that is the bokeh in question. for you... Because I know, bad me, that the mythical bokeh is hard to define even for its most faithful fans... If it is just a question of the background spherical aberration for you, be happy. But bokeh that generations speak about is not that easy, is it?
Then we spoke, - remember? - old lenses, designed specifically for the pleasant bokeh holly cow cup...

To all Bokehar fans - when you find one that qualifies (remember the requirements?) present it without any fear, the optical designer, the story behind it, you know... post #68...
As for me I have certain time limits in my hunt for the Bokehar... sorry.
Cheers to all!

[GPS]

A couple of points.

First, it is *not* difficult to quantify bokeh. Lens design programs do it routinely. As I mentioned in an earlier post, most will generate spot diagrams for different parts of the focal plane and different focussing distances. If you don't have a physicist's ability to do do convolutions in your head, some programs will generate synthetic images so you can see the effects on 'real' images.

The difficult thing is to come up with an agreed sense of what constitutes 'good' bokeh. Once you have done that, designers will make you a lens with the right package of aberrations - how close they come depends on how much you are prepared to pay.

GPS, you seem to be under the illusion that soft focus lenses are designed with only the focal plane in mind. I must confess it took me a while to realise this was what your needling was meant to convey. Perhaps the best evidence that the background was important too is the widespread use of undercorrected spherical aberration in these lenses.

...

It is not difficult to define bokeh but it is difficult to define good bokeh. Never mind the playing with words, if only you come with a clear definition of bokeh, it's already a good beginning...:)

As for my illusion, listen well - we all know that a lens calculated for the focal plane has, as a side effect, this or that bokeh, whatever that is in terms of goodness. Do you think that for a soft focus lens, calculated for the focal plane too, it would be different? It too will have some bokeh (let's leave its goodness to those who are interested) and you know what? It will be different one, what a miracle...
Now stop kidding me with a clearly defined bokeh and less clearly defined good bokeh and go to the post 68, take a deep breath and start to hunt for the Bokehar. (You already know it's just a question of spherical aberrations, don't you..?)
After all, talk is cheap but where is the beef? Cheers!:)

[GPS]

It really doesn't seem to matter-
the arguments are yours, the original topic of this thread has been long sidestepped,
and only your own agenda is at work.

Apparently, the original topic was about stopping down, and aperture blades,
and the effect it might have on the rendition of out of focus areas,
insofar as I could decipher it.

Lens design wasn't mentioned in the original proposition.

...

joseph

Joseph, I wholly agree with you, it's annoying if a thread is sidestepped.
Congratulations, You know what the thread is about.
Now what is it you said for the original topic discussed..? Pardon..?

[jb7]

I come here to learn,
and I've learned a lot here-

I agree with Jim when he says that conversations about bokeh are a relatively new phenomenon,
and discussions usually revolve about the quality of out of focus areas experienced by people using miniature formats.

I agree with him when he says that bokeh from larger formats is generally a given-
although I don't have any exotic or antique glass, the quality of bokeh (tautological) from my standard large format lenses is superior.

Bokeh is a word borrowed from the Japanese,
that is not to say that conversations about the same phenomenon haven't been part of photography and optics for centuries now-
as has been demonstrated and referenced on this thread, despite protestations to the contrary.

Bokeh is something I've only recently become acquainted with;
shooting interiors using sharp wide angles,
you tend not to come into contact with it too much.

I'd much prefer, as a photographer, to talk about the qualities of the picture
than become bogged down in a circular argument about antique lens design,
which wasn't part of the premise of the original proposition.

Photographers use lenses, get to know their character, and make lens selections based on the pictorial qualities (among other things) they want to achieve.
I'll hang on any piece of useful information, and become irked by people who seem to pick niggardly contrary arguments seemingly for their own sake,
and without making a positive addition to the conversation.

Photographers generally don't design lenses-

Last year, I did a little test, almost as an afterthought-
so the two pictures don't match particularly well-
the P55 wasn't scanned very well either...

I post it here just to prove my interest in the subject...


http://farm4.static.flickr.com/3015/2437664445_8ebd46c00c_b.jpg

The projector lens didn't have a diaphragm,
but the Nikkor ƒ/1.2 was shot wide open too.

My interpretation of 'bokeh', the quality of out of focus areas of an image,
includes rendition of those areas by lenses exhibiting abberations,
including some of the portrait lenses mentioned.

They might not have been designed with 'bokeh' in mind,
but photographers have used them with 'bokeh' in mind.

I really don't see the difficulty with this,
and would really like to get back on track,
and pick up some crumbs from those here who know what they are talking about,
and are willing to add to the conversation-


joseph

[Struan Gray]

...

http://struangray.com/miscpics/hasselblad.jpg

[GPS]

...
They might not have been designed with 'bokeh' in mind,
but photographers have used them with 'bokeh' in mind.

I really don't see the difficulty with this,
...

joseph

Neither do I Joseph and that was what is so surprisingly contested by some without having a proof of the contrary.
If you have access to the Applied Photography by Ray maybe you can find the explanation of the greater number of aperture leaves in some older lenses, surprised that nobody took that info up. Cheers!

[Ken Lee]

I'll take the blame for any distraction. It was my post which diverted the subject.

Oops ! Sorry !

[Carioca]

I come here to learn,
and I've learned a lot here-

I agree with Jim when he says that conversations about bokeh are a relatively new phenomenon,
and discussions usually revolve about the quality of out of focus areas experienced by people using miniature formats.

I agree with him when he says that bokeh from larger formats is generally a given-
although I don't have any exotic or antique glass, the quality of bokeh (tautological) from my standard large format lenses is superior.

Bokeh is a word borrowed from the Japanese,
that is not to say that conversations about the same phenomenon haven't been part of photography and optics for centuries now-
as has been demonstrated and referenced on this thread, despite protestations to the contrary.

Bokeh is something I've only recently become acquainted with;
shooting interiors using sharp wide angles,
you tend not to come into contact with it too much.

I'd much prefer, as a photographer, to talk about the qualities of the picture
than become bogged down in a circular argument about antique lens design,
which wasn't part of the premise of the original proposition.

Photographers use lenses, get to know their character, and make lens selections based on the pictorial qualities (among other things) they want to achieve.
I'll hang on any piece of useful information, and become irked by people who seem to pick niggardly contrary arguments seemingly for their own sake,
and without making a positive addition to the conversation.

Photographers generally don't design lenses-

Last year, I did a little test, almost as an afterthought-
so the two pictures don't match particularly well-
the P55 wasn't scanned very well either...

I post it here just to prove my interest in the subject...


http://farm4.static.flickr.com/3015/2437664445_8ebd46c00c_b.jpg

The projector lens didn't have a diaphragm,
but the Nikkor ƒ/1.2 was shot wide open too.

My interpretation of 'bokeh', the quality of out of focus areas of an image,
includes rendition of those areas by lenses exhibiting abberations,
including some of the portrait lenses mentioned.

They might not have been designed with 'bokeh' in mind,
but photographers have used them with 'bokeh' in mind.

I really don't see the difficulty with this,
and would really like to get back on track,
and pick up some crumbs from those here who know what they are talking about,
and are willing to add to the conversation-


joseph

Excellent 'Intermezzo' of this thread, Joseph, thank you!

Nice to see that members also use their lenses, and not only talk about them.

Sidney

[GPS]

I'll take the blame for any distraction. It was my post which diverted the subject.

Oops ! Sorry !

When it comes to me, you have my absolution. :) Notice that the OP was content with the heated debate, that says it all.
It is incredible how emotions can take over when someone dares to say - there is no old lens known in the world designed specifically for good bokeh. Wow! On baricades..!:rolleyes:

[mrpengun]

When it comes to me, you have my absolution. :) Notice that the OP was content with the heated debate, that says it all.
It is incredible how emotions can take over when someone dares to say - there is no old lens known in the world designed specifically for good bokeh. Wow! On baricades..!:rolleyes:

For a while i was wondering if I was going to have to apologize for starting such a controversial thread :-)

Either way, I think in the days where nearly the entire spectrum of photography is permeated with ultra-flat imagery, issues and thoughts regarding depth of field are worth while, regardless of how they start or where they end up.

[CCHarrison]

"SO someone invented the internal iris aperture."

That would be CC Harrison about 1857...US Patent 21,470. See my article here:

http://www.antiquecameras.net/1857ccharrisonlens.html

Dan

[ric_kb]

HTDHTT.
\This link popped up during my searching the DC lenses from Nikon...
http://imaging.nikon.com/products/imaging/technology/nikkor/n32_e.htm

it mentions their design thinking (brief, non technical) on their Defocus Control...

Richard
silverprankster.com