What lenses "Swirl"

**clackers** · 11-29-2016, 10:31 PM

And this?

Creating swirly bokeh with the Helios 44-2 lens

maltfalc · 11-29-2016, 10:33 PM

Originally posted by BrianR

Isn't the swirly bokeh (at least partially) caused by a hard optical vignetting that changes the shape of the aperture at off-axis angles? As in figure 2 here: Vignetting. There are other factors of course, so just having a deeply recessed front element isn't enough, but for a given lens if you added an inappropriately sized lens hood, or stacked a bunch of filters, the cats eye bokeh would be exaggerated? Should be easy enough to test with a roll of black cardboard and some Christmas lights.

I think there's other factors to the overall wiggy swirlies though, the soap bubble bokeh, a generally sharp thing in focus but soft elsewhere, or other funny things that tend to be "corrected" in more modern lens designs.

exactly what i've been saying, except that a deeply recessed front element can be enough on it's own, as long as it's deep enough.

stevebrot · 11-29-2016, 10:33 PM

Originally posted by maltfalc

i repeat, it takes literally a few seconds for you to see for yourself that i'm right.

What you are suggesting is outside conventional optical science and has not been experienced by this photographer in over 45 years of shooting. As with all new discoveries, the onus falls on the discovery to publish and support the assertion.

You post the photos along with the setup and we eat the crow. I believe that is easy enough.

Steve

maltfalc · 11-29-2016, 10:40 PM

Originally posted by clackers

I repeat, you have no reference.

What's your explanation with this:

New Petzval 58 Creates Bokeh Like No Other Camera Lens | Digital Trends

it's got a constricted light path and apparently a mechanism to adjust the amount of constriction and barrel distortion. so what?

---------- Post added 11-29-16 at 11:43 PM ----------

Originally posted by clackers

And this?

Creating swirly bokeh with the Helios 44-2 lens

it's a lens with swirly bokeh. so? i have no idea what your point could even be.

---------- Post added 11-29-16 at 11:52 PM ----------

Originally posted by stevebrot

What you are suggesting is outside conventional optical science and has not been experienced by this photographer in over 45 years of shooting. As with all new discoveries, the onus falls on the discovery to publish and support the assertion.

You post the photos along with the setup and we eat the crow. I believe that is easy enough.

Steve

how is it outside conventional optical science? in what specific way? or is it just in the sense that you don't understand how it works therefore you don't believe it does? it's the most basic optical geometry that anyone who understands how a lens works should be able to understand.

stevebrot · 11-29-2016, 11:04 PM

Originally posted by BrianR

Isn't the swirly bokeh (at least partially) caused by a hard optical vignetting that changes the shape of the aperture at off-axis angles? As in figure 2 here: Vignetting.

Edit: I forgot to thank you for the excellent linked article. In regards to optical vignette, an important point is that it is caused by shading of the entrance pupil (not the same as the front element).

Swirl is not the same as cats-eye highlights, though I can see how the two might be confused. The most extreme examples I have seen have been at moderate apertures (i.e. f/4 - f/5.6) of subjects with well lit, but "busy" backgrounds without obvious specular highlights. The photo below (lifted from the Helios 44 group on Flickr) is a good example.

PB200354
by Tomáš Kopecký, on Flickr

Steve

redpit · 11-29-2016, 11:04 PM - **1 Like**

Take a look here as well:
https://www.pentaxforums.com/forums/54-pentax-lens-articles/289699-helios-40-...keh-swirl.html

and here is an example with my K-5IIs:

stevebrot · 11-29-2016, 11:06 PM

Originally posted by maltfalc

it's got a constricted light path and apparently a mechanism to adjust the amount of constriction and barrel distortion. so what?

---------- Post added 11-29-16 at 11:43 PM ----------

it's a lens with swirly bokeh. so? i have no idea what your point could even be.

---------- Post added 11-29-16 at 11:52 PM ----------

how is it outside conventional optical science? in what specific way? or is it just in the sense that you don't understand how it works therefore you don't believe it does? it's the most basic optical geometry that anyone who understands how a lens works should be able to understand.

You don't want to show and tell?

Fair enough.

Steve

maltfalc · 11-29-2016, 11:45 PM

Originally posted by stevebrot

Swirl is not the same as cats-eye highlights, though I can see how the two might be confused. The most extreme examples I have seen have been at moderate apertures (i.e. f/4 - f/5.6) of subjects with well lit, but "busy" backgrounds without obvious specular highlights.* The photo below (lifted from the Helios 44 group on Flickr) is a good example.

Steve

it is exactly the same. every out of focus spot in the background is spread out in the same shape as the oof highlights, it's just not as noticeable as the shape of a single bright spot surrounded by a darker area. the cat's eye shape means every part of the oof background is smeared more along one axis than the other as you get closer to the edges. that all "swirl" is.

Supakatti · 11-29-2016, 11:52 PM - **1 Like**

Daguerrotype Achromat 64mm 1:2.9 by Lomography shot wide open with K-1:

maltfalc · 11-30-2016, 12:11 AM

Originally posted by stevebrot

You don't want to show and tell?

Fair enough.

Steve

again, what is it specifically that you think is outside conventional optical science? what the heck am i supposed to be demonstrating?

stevebrot · 11-30-2016, 12:16 AM

Originally posted by maltfalc

it is exactly the same. every out of focus spot in the background is spread out in the same shape as the oof highlights, it's just not as noticeable as the shape of a single bright spot surrounded by a darker area. the cat's eye shape means every part of the oof background is smeared more along one axis than the other as you get closer to the edges. that all "swirl" is.

I guess that is one way of looking at it, though consensus has been in the past that it is a form of poorly controlled circular aberration. Given your definition, swirly bokeh should be pretty much everywhere, but strangely, it is sort of rare.

That is why I suggested you reproduce it for us using a widely available lens, not some exotic former Soviet glass like the Helios 44 or Helios 40-2. I have a wide variety of fast 50s (25+), almost all of which are capable of cats-eye highlights, but only one of which is capable of swirly bokeh and then only rarely. A sure formula for producing the effect without a special lens would be a welcome technique for many users on this site since the question of "swirly lens" comes up frequently.

Steve

stevebrot · 11-30-2016, 12:22 AM

Originally posted by maltfalc

...what the heck am i supposed to be demonstrating?

Swirly bokeh?

Show us how to generate it at will using a hood or stepdown ring.

Steve

maltfalc · 11-30-2016, 12:42 AM

Originally posted by stevebrot

I guess that is one way of looking at it, though consensus has been in the past that it is a form of poorly controlled circular aberration. Given your definition, swirly bokeh should be pretty much everywhere, but strangely, it is sort of rare.

That is why I suggested you reproduce it for us using a widely available lens, not some exotic former Soviet glass like the Helios 44 or Helios 40-2. I have a wide variety of fast 50s (25+), almost all of which are capable of cats-eye highlights, but only one of which is capable of swirly bokeh and then only rarely. A sure formula for producing the effect without a special lens would be a welcome technique for many users on this site since the question of "swirly lens" comes up frequently.

Steve

most lenses do produce swirl, they're just designed with wide enough elements and lens barrels that they don't begin to clip the edges of the light path significantly and produce a noticeable swirl until well beyond the edge of the sensor/film. cut a circular hole in a piece of cardboard and attach it to the front of your lens. the hole should be just barely big enough not to clip the edges of oof highlights in the center of the image. or salvage an iris from a broken lens and glue it to a filter ring. hell, make an o shape with your thumb and index finger in front of your lens if you can't be bothered to deal with scissors and cardboard. i can't simplify this any more than that. it's not rocket science, it's barely even arts and crafts.

stevebrot · 11-30-2016, 12:49 AM - **1 Like**

Originally posted by maltfalc

i can't simplify this any more than that. it's not rocket science, it's barely even arts and crafts.

Have a good day tomorrow. It is rare that I allow myself to be trolled, but enough is enough.

Steve

(...am expert rocket surgeon...)

**BigMackCam** · 11-30-2016, 12:56 AM - **1 Like**

@stevebrot and @maltfalc (and everyone else

) - there's an interesting (if inconclusive) discussion on the causes of "swirly bokeh" here: optics - What is the cause of this non-uniform bokeh effect? - Photography Stack Exchange - scroll down or search to find the answer that begins "There is a prevalent Internet theory which holds that this is primarily due to optical vignetting". Here, the poster tests out the theory @maltfalc is suggesting, by introducing gradually more masking / vignetting at the front of the lens. It does indeed produce a very limited amount of swirl at the edges (most visible when the image circle is reduced to less than the full frame), but absolutely not the full-on effect we see with Biotars, Biotar-derived Helios, my Vivitar, and various other "swirly bokeh" lenses. His conclusion is that while optical vignetting may be a contributing factor, it's just one component and not the whole story.

11-29-2016, 11:04 PM	#35
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by BrianR Isn't the swirly bokeh (at least partially) caused by a hard optical vignetting that changes the shape of the aperture at off-axis angles? As in figure 2 here: Vignetting. Edit: I forgot to thank you for the excellent linked article. In regards to optical vignette, an important point is that it is caused by shading of the entrance pupil (not the same as the front element). Swirl is not the same as cats-eye highlights, though I can see how the two might be confused. The most extreme examples I have seen have been at moderate apertures (i.e. f/4 - f/5.6) of subjects with well lit, but "busy" backgrounds without obvious specular highlights. The photo below (lifted from the Helios 44 group on Flickr) is a good example. PB200354 by Tomáš Kopecký, on Flickr Steve Last edited by stevebrot; 11-30-2016 at 12:01 AM.

11-29-2016, 11:52 PM - 1 Like	#39
Supakatti Senior Member Join Date: Feb 2014 Location: Tuusula, Southern Finland Photos: Albums Posts: 135	Daguerrotype Achromat 64mm 1:2.9 by Lomography shot wide open with K-1: Attached Images

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11-29-2016, 10:31 PM	#31
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	And this? Creating swirly bokeh with the Helios 44-2 lens

11-29-2016, 10:33 PM	#32
maltfalc Veteran Member Join Date: May 2010 Location: Winnipeg Photos: Albums Posts: 396	Originally posted by BrianR Isn't the swirly bokeh (at least partially) caused by a hard optical vignetting that changes the shape of the aperture at off-axis angles? As in figure 2 here: Vignetting. There are other factors of course, so just having a deeply recessed front element isn't enough, but for a given lens if you added an inappropriately sized lens hood, or stacked a bunch of filters, the cats eye bokeh would be exaggerated? Should be easy enough to test with a roll of black cardboard and some Christmas lights. I think there's other factors to the overall wiggy swirlies though, the soap bubble bokeh, a generally sharp thing in focus but soft elsewhere, or other funny things that tend to be "corrected" in more modern lens designs. exactly what i've been saying, except that a deeply recessed front element can be enough on it's own, as long as it's deep enough.

11-29-2016, 10:33 PM	#33
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by maltfalc i repeat, it takes literally a few seconds for you to see for yourself that i'm right. What you are suggesting is outside conventional optical science and has not been experienced by this photographer in over 45 years of shooting. As with all new discoveries, the onus falls on the discovery to publish and support the assertion. You post the photos along with the setup and we eat the crow. I believe that is easy enough. Steve

11-29-2016, 10:40 PM	#34
maltfalc Veteran Member Join Date: May 2010 Location: Winnipeg Photos: Albums Posts: 396	Originally posted by clackers I repeat, you have no reference. What's your explanation with this: New Petzval 58 Creates Bokeh Like No Other Camera Lens \| Digital Trends it's got a constricted light path and apparently a mechanism to adjust the amount of constriction and barrel distortion. so what? ---------- Post added 11-29-16 at 11:43 PM ---------- Originally posted by clackers And this? Creating swirly bokeh with the Helios 44-2 lens it's a lens with swirly bokeh. so? i have no idea what your point could even be. ---------- Post added 11-29-16 at 11:52 PM ---------- Originally posted by stevebrot What you are suggesting is outside conventional optical science and has not been experienced by this photographer in over 45 years of shooting. As with all new discoveries, the onus falls on the discovery to publish and support the assertion. You post the photos along with the setup and we eat the crow. I believe that is easy enough. Steve how is it outside conventional optical science? in what specific way? or is it just in the sense that you don't understand how it works therefore you don't believe it does? it's the most basic optical geometry that anyone who understands how a lens works should be able to understand.

11-29-2016, 11:06 PM	#37
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by maltfalc it's got a constricted light path and apparently a mechanism to adjust the amount of constriction and barrel distortion. so what? ---------- Post added 11-29-16 at 11:43 PM ---------- it's a lens with swirly bokeh. so? i have no idea what your point could even be. ---------- Post added 11-29-16 at 11:52 PM ---------- how is it outside conventional optical science? in what specific way? or is it just in the sense that you don't understand how it works therefore you don't believe it does? it's the most basic optical geometry that anyone who understands how a lens works should be able to understand. You don't want to show and tell? Fair enough. Steve

11-29-2016, 11:45 PM	#38
maltfalc Veteran Member Join Date: May 2010 Location: Winnipeg Photos: Albums Posts: 396	Originally posted by stevebrot Swirl is not the same as cats-eye highlights, though I can see how the two might be confused. The most extreme examples I have seen have been at moderate apertures (i.e. f/4 - f/5.6) of subjects with well lit, but "busy" backgrounds without obvious specular highlights.* The photo below (lifted from the Helios 44 group on Flickr) is a good example. Steve it is exactly the same. every out of focus spot in the background is spread out in the same shape as the oof highlights, it's just not as noticeable as the shape of a single bright spot surrounded by a darker area. the cat's eye shape means every part of the oof background is smeared more along one axis than the other as you get closer to the edges. that all "swirl" is.

11-30-2016, 12:11 AM	#40
maltfalc Veteran Member Join Date: May 2010 Location: Winnipeg Photos: Albums Posts: 396	Originally posted by stevebrot You don't want to show and tell? Fair enough. Steve again, what is it specifically that you think is outside conventional optical science? what the heck am i supposed to be demonstrating?

11-30-2016, 12:16 AM	#41
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by maltfalc it is exactly the same. every out of focus spot in the background is spread out in the same shape as the oof highlights, it's just not as noticeable as the shape of a single bright spot surrounded by a darker area. the cat's eye shape means every part of the oof background is smeared more along one axis than the other as you get closer to the edges. that all "swirl" is. I guess that is one way of looking at it, though consensus has been in the past that it is a form of poorly controlled circular aberration. Given your definition, swirly bokeh should be pretty much everywhere, but strangely, it is sort of rare. That is why I suggested you reproduce it for us using a widely available lens, not some exotic former Soviet glass like the Helios 44 or Helios 40-2. I have a wide variety of fast 50s (25+), almost all of which are capable of cats-eye highlights, but only one of which is capable of swirly bokeh and then only rarely. A sure formula for producing the effect without a special lens would be a welcome technique for many users on this site since the question of "swirly lens" comes up frequently. Steve

11-30-2016, 12:22 AM	#42
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by maltfalc ...what the heck am i supposed to be demonstrating? Swirly bokeh? Show us how to generate it at will using a hood or stepdown ring. Steve

11-30-2016, 12:42 AM	#43
maltfalc Veteran Member Join Date: May 2010 Location: Winnipeg Photos: Albums Posts: 396	Originally posted by stevebrot I guess that is one way of looking at it, though consensus has been in the past that it is a form of poorly controlled circular aberration. Given your definition, swirly bokeh should be pretty much everywhere, but strangely, it is sort of rare. That is why I suggested you reproduce it for us using a widely available lens, not some exotic former Soviet glass like the Helios 44 or Helios 40-2. I have a wide variety of fast 50s (25+), almost all of which are capable of cats-eye highlights, but only one of which is capable of swirly bokeh and then only rarely. A sure formula for producing the effect without a special lens would be a welcome technique for many users on this site since the question of "swirly lens" comes up frequently. Steve most lenses do produce swirl, they're just designed with wide enough elements and lens barrels that they don't begin to clip the edges of the light path significantly and produce a noticeable swirl until well beyond the edge of the sensor/film. cut a circular hole in a piece of cardboard and attach it to the front of your lens. the hole should be just barely big enough not to clip the edges of oof highlights in the center of the image. or salvage an iris from a broken lens and glue it to a filter ring. hell, make an o shape with your thumb and index finger in front of your lens if you can't be bothered to deal with scissors and cardboard. i can't simplify this any more than that. it's not rocket science, it's barely even arts and crafts.

11-30-2016, 12:49 AM - 1 Like	#44
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by maltfalc i can't simplify this any more than that. it's not rocket science, it's barely even arts and crafts. Have a good day tomorrow. It is rare that I allow myself to be trolled, but enough is enough. Steve (...am expert rocket surgeon...)

11-30-2016, 12:56 AM - 1 Like	#45
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	@stevebrot and @maltfalc (and everyone else ) - there's an interesting (if inconclusive) discussion on the causes of "swirly bokeh" here: optics - What is the cause of this non-uniform bokeh effect? - Photography Stack Exchange - scroll down or search to find the answer that begins "There is a prevalent Internet theory which holds that this is primarily due to optical vignetting". Here, the poster tests out the theory @maltfalc is suggesting, by introducing gradually more masking / vignetting at the front of the lens. It does indeed produce a very limited amount of swirl at the edges (most visible when the image circle is reduced to less than the full frame), but absolutely not the full-on effect we see with Biotars, Biotar-derived Helios, my Vivitar, and various other "swirly bokeh" lenses. His conclusion is that while optical vignetting may be a contributing factor, it's just one component and not the whole story.