What lens type causes the "circular" blur/bokeh?

[stevegoldenberg]

I'm trying to figure out if there is a specific type of lens that causes that interesting "circular" blur in the background of certain images. It seems to be more prevalent on older lenses rather than new ones. I realize that's a crappy description but I can't think of another way to describe it. Any of you know?

 

[wilonstott]

I believe this is an artifact of non-asph designs, because the bokeh is not or may not be perfectly round the farther it gets from center; however, I could be mistaken.
For example, the Nokton 35mm f/1.4 (non-asph summilux copy) does it:

Also, be aware that it even with lenses that render this effect, specific conditions are required--this is why you mainly see it with light though foliage, as with my photo, or with a background of city lights (to name a few).

 

[Robert Lai]

This is typically referred to as "swirly bokeh". If you google this, several suggestions pop up, typically the Zeiss Biotar 58/2. I've seen some of this with other fast lenses.

Triplets typically do this - try a Zeiss Super Ikonta with a Novar. My Super Ikonta with 80 f/2.8 Tessar seems to swirl a bit too.

You need foliage or dappled light in the background to give the full swirly look.

 

[alienmeatsack]

Is this the effect you are talking about, where the depth of field is tight and the areas outside of it tend to look almost like they were run through a blur filter that rotates a little?


MIR-WWP-04062013-38 by alienmeatsack, on Flickr

This is what my Auto Miranda 50mm does at it's largest aperture setting, and the effect tends to be more pronounced when there is a dramatic change in distance between the focus point and the fore/back grounds, like in the above shot. I just assumed it was one of the characteristics of the lens like some lenses having a certain feel to their bokeh.

 

[theno23]

If you mean the bokeh rings, that's caused by cadiotropic mirror lenses. I don't think there are any with rangefinder couplings though?

They're not common anymore, but used to be in telephoto designs.

They're compact, fast, and focus down to close distances, but the bokeh is weird.
http://en.wikipedia.org/wiki/File:Catadioptric_system_bokeh_christmas_tree_lights.jpg

- Steve

 

[theno23]

Actually there was one: http://imaging.nikon.com/history/nikkor/13/

A Nikon S-mount 1000mm - I gues you had to use it with a reflex housing, like a visoflex.

 

[Highway 61]

I'm trying to figure out if there is a specific type of lens that causes that interesting "circular" blur in the background of certain images.

So you're talking about the "swirly bokeh".

This is caused by some spherical aberration. So you get it with lenses suffering from this peculiar optical aberration.

Back in the days when that darn "bokeh" concept didn't exist yet, optical ingeneers were struggling to make lenses which wouldn't exhibit what was still considered to be a nasty defect.

This is why you can't have it with modern lenses.

Now that "bokeh" has become as important as, say, the composition and the general message delivered by a photograph, the old nasty spherical aberration has changed itself into the hype swirly bokeh many of us are after... 😎

 

[Sylvester]

So you're talking about the "swirly bokeh".

This is caused by some spherical aberration. So you get it with lenses suffering from this peculiar optical aberration.

Back in the days when that darn "bokeh" concept didn't exist yet, optical ingeneers were struggling to make lenses which wouldn't exhibit what was still considered to be a nasty defect.

This is why you can't have it with modern lenses.

Now that "bokeh" has become as important as, say, the composition and the general message delivered by a photograph, the old nasty spherical aberration has changed itself into the hype swirly bokeh many of us are after... 😎

You mean it's as important than the rest if it's a photographer that looks at the image, right?

 

[Monochrom]

Try with lenses that have a more blades...those make circular iris as you move the aperture...the less blades the iris makes a hexagonal like shape.
Also i´ve noticed bokeh has to do where the diafragm is set between the optical elemnts...but about that i have nothing serious to say..😉

 

[goamules]

It's Coma, another of the 6 aberrations in lenses. It's not Spherical Aberration, which causes softness or fuzziness. Faster lenses do it, and earlier types, but correcting one problem led to others, so it depends on what the particular lens design was tying to do. Nikkor 50/1.4s do it.

 

[Highway 61]

Try with lenses that have a more blades...those make circular iris as you move the aperture...the less blades the iris makes a hexagonal like shape.

Go to flickr and look for images using "swirly bokeh" - "swirl bokeh" - "swirling bokeh" search keywords : you'll understand what he's asking. 😉

Beautiful examples here.

It's Coma, another of the 6 aberrations in lenses. It's not Spherical Aberration, which causes softness or fuzziness.

Not too sure (the consequences of coma are some visible "comets tails" seeming to following the highlights dots - hence the name of it) but I'd like to stand corrected if you have examples and schemes.
A few people also say it's astigmatism but it for sure isn't ; for what I've been told it's spherical aberration.

But - again - I would like to stand corrected.

You mean it's as important than the rest if it's a photographer that looks at the image, right?

I mean : if somebody being after that bokeh thing already looks at the image... Not all "photographers" are obsessed with bokeh yet. 😉

 

[goamules]

...


Not too sure (the consequences of coma are some visible "comets tails" seeming to following the highlights dots - hence the name of it) but I'd like to stand corrected if you have examples and schemes.
A few people also say it's astigmatism but it for sure isn't ; for what I've been told it's spherical aberration.

But - again - I would like to stand corrected.

...

I've already corrected you. Go do some research and report back. I already know the difference between Coma, Spherical Aberration, Astigmatism, Rectilinear distortion...and several more. I'm not going to explain the science here. Start here:
http://en.wikipedia.org/wiki/Optical_aberration

 

[goamules]

Petzvals, the earliest fast lens design, often do it. But very few Petzvals are in 35mm mounts. Several cine lenses will swirl, and are Petzvlas, but they won't cover 35mm, only m4/3. Here is an example from one of mine on about 5x7:

 

[ferider]

Agree with Garrett.

In any case, for the OP, almost all lenses have it. Just depends on the degree, the lens being used wide open (when #aperture blades doesn't matter), and the right background to make it visible.

For example, here it is with a Leica M Summicron:

If you want a lens that exhibits coma strongly, let us know which camera you use, and we can help. For example, for a Leica, I would suggest a Summitar, classic Summarit or f1.0 Noctilux 🙂

Roland.

 

[Highway 61]

I've already corrected you. Go do some research and report back. I already know the difference between Coma, Spherical Aberration, Astigmatism, Rectilinear distortion...and several more. I'm not going to explain the science here. Start here:
http://en.wikipedia.org/wiki/Optical_aberration

Thanks.

This is now clearer for me. To my defense many great optics specialists I had asked had told me that it was spherical aberration.

This picture clearly shows why coma gives that swirly bokeh :

Yet I may now think that pleasant swirly bokeh is due to coma and a bit of spherical aberration at the same time. A lens with coma but without spherical aberration wouldn't produce nice elliptic oof evenly illuminated highlights spots, but rather unpleasant triangles with a more luminous spot at an edge.

It's always nice to learn things. Thanks again.

As an aside I once was successful at getting some with a Millenium Nikkor 50/1.4 :

Nikon SP - Millenium Nikkor 50/1.4 - Fuji Reala 100

This was a kind of "exercise" shot, I was wanting to see if the Millenium Nikkor had it.

But your Petzval portrait of the man playing guitar is beautiful.

 

[goamules]

Wow, I like that Nikkor picture!