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Old 01-24-2008   #251
Bryce
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Swirly lenses seem to concentrate light in the OOF into the edge of the circles of confusion nearest the center of the image. They also seem to distort the circle a little, into more of a hyperbola shape.
Could this be astigmatism showing up OOF only? I guess you could test by taking a swirly lens and making a picture with point sources in the foreground OOF. They would form radial lines instead...
Just a guess.
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Old 01-24-2008   #252
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When I Google "swirly bokeh," most of the examples are from large format lenses (supposedly the 3-element lenses are the most likely to get swirly) and the 50/1.0 Noctilux. Some more I just came across with swirly bokeh are the Classic Heliar 50/2, Helios 40-2 85/1.5, 50 Summitar, and the original Nokton.
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Old 01-25-2008   #253
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Thanks, Amin, for your kind comments regarding my pictures.

Quote:
Originally Posted by amin_sabet
When I Google "swirly bokeh," most of the examples are from large format lenses (supposedly the 3-element lenses are the most likely to get swirly) and the 50/1.0 Noctilux. Some more I just came across with swirly bokeh are the Classic Heliar 50/2, Helios 40-2 85/1.5, 50 Summitar, and the original Nokton.
I agree with LF specialist Ole Tjugen in this post: swirly bokeh comes from astigmatism and vignetting. I would go a bit further in saying that it comes mainly from mechanical vignetting due to the rear part of the lens mount blocking some light rays around the edges of the frame, thus turning circles into "cat eyes" shapes. But, as you can see if you read the whole thread, this matter is subject to discussion.

I have some pictures exhibiting this swirly bokeh. Most were taken with large format or medium format lenses, some with the Bessa R3M equipped with the Canon 50/0.95 or the Heliar 50/2. They were all taken with fast lenses used wide open and focused close.

If you want to duplicate the effect, put your subject in the center of the frame in front of a "busy" background located not too far away from the main subject (like some twigs with leaves on them and light filtering through), because the swirly bokeh will not show if the background is completely out of focus. The best lenses are usually those with large glass elements inserted in long tubes, because they will exhibit the greatest amount of mechanical vignetting. You can also adapt a black cardboard tube at the rear of your lens (like a narrow lens hood, but attached behind the lens) to enhance vignetting.

This is my favorite "swirly bokeh" picture (linked from the awesome Kerik Kouklis' website, shot with an 18" LF Verito lens):



Cheers!

Abbazz
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Old 01-25-2008   #254
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That's a great shot! Here are some shirly shots by others which I enjoyed finding while looking for examples:

3 swirly shots by Tommy Oshima:
http://www.flickr.com/photos/tommyoshima/281078121/
http://www.flickr.com/photos/tommyoshima/445174821/
http://www.flickr.com/photos/tommyoshima/246989204/

Gabriel M.A.:
http://www.flickr.com/photos/gabrielma/1862504810/

Moaan:
http://www.flickr.com/photos/moaan/2039843441/

Nomad on the road films (Not as swirly, but I like it):
http://www.flickr.com/photos/pm_photo/524838305/

Tetsuya Miyoshi with some of that sweet Summitar swirl:
http://www.flickr.com/photos/d-chimpanzee/463127282/

My Zuiko OM 50/1.2 has a pretty large rear element, but no tube around it. I'm afraid to put cardboard there since the pesky mirror might not clear it. Ah well, I'll pick up a swirly lens at some point. Thanks for the explanation and tips!
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Old 01-25-2008   #255
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taken with 35 asph sum.
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Old 01-25-2008   #256
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Quote:
Originally Posted by amin_sabet
Abbazz, I enjoyed your 50/0.95 images. Anyone know of any other lenses for 35mm photography, other than the Noctilux 50/1 and Canon 50/0.95 that produce the kind of "swirly bokeh" seen in the above image? I really like the effect.
The swirl is caused by coma. The Noctilux, Summitar and Summarit (classic)
are very good at that.

Sunlit leaves in the background are always good to generate it.

Roland.
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Old 01-25-2008   #257
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Some thoughts in Wiki about Bokeh

http://en.wikipedia.org/wiki/Bokeh
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Old 01-25-2008   #258
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You call that Bokeh?


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Old 01-25-2008   #259
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Quote:
Originally Posted by ferider
The swirl is caused by coma.
Roland,

Let me quote Ole Tjugen (from the post precedently linked):
coma forms "light trails" away from the image center, not around it

When you take the image of a starry night sky with a lens suffering from a lot of coma, each off center star is transformed into a comet like shape (hence the name "coma"), with the tail of the comet radiating toward the edge of the frame (radial orientation). This is not what we see in "swirly bokeh," where the peripheral highlights are turned into cat eye shapes with a concentric orientation.

Another quote from Ole's post:
when you tilt a lens you will see that there is some point at which the aperture starts to look like a lozenge (or american football) and not an ellipse. Out-of-focus highlights will reflect this change in shape, becoming narrower with increasing distance from the center.
That's why it is possible to generate this swirly bokeh on large format by adding some vignetting by mechanical means (a black cardboard tube behind the lens).

Cheers!

Abbazz
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Old 01-25-2008   #260
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Abbazz,

more often, coma is referred to as any aberration producing any kind of asymmetrical distortion of points in the image. Since lenses are round, typically these distortions appear in radial symmetry to the image center, which creates the impression of circles. Tails, comet stars and shapes that look like flying birds are only one variant. Elipses are another one.

Puts uses this definition, for instance (he provides a nice overview of the 7 Seidel aberrations). He also says:

Quote:
spherical aberration and coma can only be combated by contrast reduction, evenness of definition over the image area, focus shift, vignetting and a host of other optical parameters.
Which explains why you often see contrast/resolution reduction but less coma, for example in the corners of the typical Sonnar-taken picture.

Best,

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Last edited by ferider : 01-25-2008 at 17:29.
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Old 01-25-2008   #261
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Quote:
Originally Posted by ferider
more often, coma is referred to as any aberration producing any kind of asymmetrical distortion of points in the image. Since lenses are round, typically these distortions appear in radial symmetry to the image center, which creates the impression of circles. Tails, comet stars and shapes that look like flying birds are only one variant. Elipses are another one.
Roland, let me call old Kingslake (Lenses in Photography, Garden City Books, New York, 1951) to the rescue:

Coma has the effect of producing a rather unpleasant one-sided radial blurring of images lying in the outer parts of the field. (emphasis is mine)

Here's the paragraph about vignetting, from the same book:



Cheers!

Abbazz
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Old 01-25-2008   #262
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Quote:
Originally Posted by Abbazz
Roland, let me call old Kingslake (Lenses in Photography, Garden City Books, New York, 1951) to the rescue:

Coma has the effect of producing a rather unpleasant one-sided radial blurring of images lying in the outer parts of the field. (emphasis is mine)
I think we agree, Abbazz. Allow me to illustrate using your picture. Looks
like one-sided radial blurring to me.

Roland.
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Old 01-25-2008   #263
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Quote:
Originally Posted by ferider
I think we agree, Abbazz. Allow me to illustrate using your picture. Looks
like one-sided radial blurring to me.
Roland, the problem I have with your concept is that coma also affects highlights in sharp focus. I have never seen those comet shaped highlights that should be present in the areas of sharp focus on shots taken with the Noctilux or the Classic Heliar 50/2. I have never heard that the Heliar is affected by coma either.

Cheers!

Abbazz
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Old 01-25-2008   #264
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Quote:
Originally Posted by Abbazz
Roland, the problem I have with your concept is that coma also affects highlights in sharp focus.
I'm flattered but it's not my concept, Abbazz. I guess it's a softening of terms over time. It used to be called sagittal oblique spherical aberration, but now many people - me included - just call it coma.

See for instance http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00MSoT Scroll to the very end which shows a butterfly example - (I saw my first example, called coma there, too, in the Leica Lens Compendium I think).

The strict definition of the term as you use it is found for telescopes, I believe, not really for photographic lenses. But I'm an electrical engineer not a physicist

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Osterloh Leica M book reference
Old 01-25-2008   #265
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Osterloh Leica M book reference

Roland,

Would you consider the p. 103 explanation of coma accurate - "Coma causes individual points of light to be reproduced as butterfly-like images. The further away the point is from the center of the image, the more pronounced is the effect?

The image shows a dot at image radius 0mm moving to a sideways teardrop to a sideways chocolate kiss eventually to a butterfly or arrow shape at 18mm.

I also don't see the swirly bokeh in the small sample of Noctilux photos I've taken, but I have seen non-circular football shaped lights in the OOF areas in mine, and other Noct photos, which I kind of like, along with the watercolor painting effect, that I can't quite clarify, as it's not defined in any of the books I have.


Quote:
Originally Posted by ferider
I'm flattered but it's not my concept, Abbazz. I guess it's a softening of terms over time. It used to be called sagittal oblique spherical aberration, but now many people - me included - just call it coma.

See for instance http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00MSoT Scroll to the very end which shows a butterfly example - (I saw my first example, called coma there, too, in the Leica Lens Compendium I think).

The strict definition of the term as you use it is found for telescopes, I believe, not really for photographic lenses. But I'm an electrical engineer not a physicist

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Old 01-25-2008   #266
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Yes, Ted, except butterflies are the extremes. Can be elipses/footballs, too,
in a better corrected lens. Just radially symmetric, and the further
away from the center the worse.

==================

OK. Enough techno lingo. How about bokeh in a lens on hyperfocal ?

Summicron 50/2 collapsible:



J/K More pics please ....

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Old 01-26-2008   #267
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the lens that was the King ( or Queen?) of swirlies was that Paxette lens that Brian cobbled up in LTM and owned by our very own Raid.
this thing had swirlies to spare.
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Old 01-26-2008   #268
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Quote:
Originally Posted by ampguy
Roland,

Would you consider the p. 103 explanation of coma accurate - "Coma causes individual points of light to be reproduced as butterfly-like images. The further away the point is from the center of the image, the more pronounced is the effect?

The image shows a dot at image radius 0mm moving to a sideways teardrop to a sideways chocolate kiss eventually to a butterfly or arrow shape at 18mm.

I also don't see the swirly bokeh in the small sample of Noctilux photos I've taken, but I have seen non-circular football shaped lights in the OOF areas in mine, and other Noct photos, which I kind of like, along with the watercolor painting effect, that I can't quite clarify, as it's not defined in any of the books I have.
Here is an example of the KomaKing in action. No lens produces the beautiful coma that this one does (full frame shot)...


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Old 01-26-2008   #269
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Well I don't know much about lenses, but coma and specifically sagittal oblique spherical aberration are intrinsice lens properties, right? If Abbazz is correct that attaching a cardboard tube to mechanically vignette the rear element causes the swirly bokeh, then it can't be due to coma, can it?
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Old 01-26-2008   #270
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Quote:
Originally Posted by gdi
Here is an example of the KomaKing in action. No lens produces the beautiful coma that this one does (full frame shot).
That is awesome! Christmas lights?!
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Old 01-26-2008   #271
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Quote:
Originally Posted by amin_sabet
Well I don't know much about lenses, but coma and specifically sagittal oblique spherical aberration are intrinsice lens properties, right? If Abbazz is correct that attaching a cardboard tube to mechanically vignette the rear element causes the swirly bokeh, then it can't be due to coma, can it?
Try it and report Any more pics to share ?
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Old 01-26-2008   #272
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Quote:
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That is awesome! Christmas lights?!
Yes, Rock Center Christmas tree with 400UC film...
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Old 01-26-2008   #273
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Please excuse the sentimental nature of the subject. As a model, she is easily bribed.

This was a test shot taken with a 1920s 6" Cooke on a 6x9 Thornton Pickard SLR. I have seen a few exapmples of swirly bokeh from old lenses. Personally speaking, I find that too distracting. I prefer what I can get with old Cookes.
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Old 01-26-2008   #274
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Roland: Love the night shot of the cathedrals at Lyon. Funny how a photo can make me hungry and thirsty .

Here's a couple of shots with the 35mm UC Hexanon on the R-D1 at f2.0.

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Old 01-26-2008   #275
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Quote:
Originally Posted by foto_fool
Roland: Love the night shot of the cathedrals at Lyon. Funny how a photo can make me hungry and thirsty .
I proposed it for the planned RFF Europe get together. But the crew preferred Berlin. They don't know what they're missing, John ! Nice photos.
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