Let's talk "Bokeh" ...

[Robin Harrison]

Regit, here is a link to an article written by Henry Merklinger for Photo Techniques magazine in 1997 which may help you in your research: Merklinger Bokeh
This link can be found at this site:Merklinger Articles

Excellent article. And figures 6 and 7 were EXACTLY what I was trying to propose in my previous rambling thread! Should've know someone had gotten there first.

There are no original thoughts left in this world. Photographs, on the other hand...

 

[Craig M]

I think it's best explained by Erwin Puts:

"Bokeh is a very elusive concept. It is related to the shape of out-of focus object details and the light-energy distribution within the unsharpness patches. It might be measured scientifically but no one knows how and thus subjective interpretations abound.
Bokeh is not a function of spherical aberration and number of diaphragm blades. Clearly the out-of-focus areas in front of and after the sharpness plane are different depending on the overall aberration correction, which involves much more than just the correction of spherical aberration.
Bokeh is not (and here I differ from almost anyone) a conscious design decision. Lens designers focus all their creativity to the plane of best focus and try to get an image quality that is consistent with their goals. As a general statement I would say that the clear rendition of extremely fine detail with high contrast and excellent
shape preservation over the whole image area and over all distances and apertures would be the idea. This is not easy to accomplish and so compromises have to be made. A certain 'residue' of aberrations will be present in every lens. What this residue is composed of, depends on the compromise made. Now it is easy to understand that the way the plane of sharpness is defined has a bearing on the unsharpness areas in front of and beyond this plane. So the unsharpness rendition is a direct function from the degree of correction of the sharpness plane."

 

[yossarian]

While appreciating both sides of this discussion, I personally believe that bokeh is in the eye of the beholder.
I am a self-confessed (and unrepentent) aficianado of "bad" bokeh. Some of my favorite images are from my Helios-40 85/1.5 which does seemingly impossible
things with OOF images, and I love every bizarre and twisted aspect of it.
It would seem (just an observation) that the better-corrected the lens, the better-
behaved the bokeh. But for me the OOF images from my Planar 50/1.7 were ugly and blocky.
I'm not trying to convert anyone here, just confessing my sins.

 

[back alley]

bokeh ---- much ado about nothing

 

[kunihiko]

New set of vocabulary sounds good. A japanese word "bokeh" could be confusing. Have a new word in english language (or chinese) and keep "bokeh" as another mistery of a small island in the far east.

 

[regit]

Thank you all your your valuable feedback, link, article, suggestions and humor 🙂 Bokeh has always facinates me and I think is something that could be explored if it is better defined; rather than trivialising it or relegate it to some arcane status... Indeed, defining bokeh is like defining the taste of an orange ... but at least me know what's sweet and what's sour ...

Right ... anyone want to have a crack at "Wabi Sabi"???? 😀

 

[erichard44]

I am glad I found this thread: I really like this approach to the topic. How many times have I read, "Oh, the lens is sharp enough, but the bokeh is terrible..."and then the poster proceeds to give an opinion which is nothing more than an illustrated anecdote. And the text concluding the anecdote is usually nothing more than a paean to a gloriously expensive lens owned by the poster. There appears to me to be no neutral or accepted way to evaluate bokeh. Maybe this is a way to start?

 

[foto_fool]

In real life I am a professional winemaker - have been for over 20 years. Managed a wine analysis laboratory. Consulted for 30+ different wineries. You can put a wine or a group of wines in front of me and I can dissect and describe nuances down to a scintilla.

I have found that this exercise of a native ability is devoid of hedonic pleasure. My ability to tell you what the characteristics of a wine are is utterly different from me telling you whether I LIKE the wine in question. I can and do like many wines that my analytical side may find flawed in some perhaps minute, perhaps not so small, way.

I can appreciate that regit and others are working toward a descriptive vocabulary for bokeh. The subject is important to me as I am a slave to fast lenses shot wide open. I can see that possessing such a vocabulary and being able to converse with experts might help me take better pictures.

But evaluating whether I like the bokeh I achieve in my shots will always engage a completely separate part of my brain. Like Potter Stewart - "I know good bokeh when I see it."

- John

 

[Morca007]

foto_fool - The modified Potter quote is the best thing I've seen thus far.

Take two photographers, and show them something shot wide open with fast glass, and you'll get two different opinions of the Bokeh.

 

[mike goldberg]

Bokeh... very much like the Hebrew word "boker" for morning...
and "tov" for good. Bokeh tov, and thanks
for the Links. I like the Luminous landscape article.
Cheers, mike ;-)

 

[JoeV]

re: Luke Howard

re: Luke Howard

I admire this attempt to name what is a rather nebulous and hard to describe optical phenomenon.

And the disagreement over the terminology, or whether there can, in fact, be accurate terminology that everyone can agree on, reminds me of a book I just finished reading this week, called "The Man Who Named the Clouds", which is the story of Luke Howard's success in defining not only names for clouds, but names that make sense in terms of the physical processes that form them.

Having names for various kinds of bokeh makes sense if one can understand them discretely as specifically identifiable phenomenon.

There's more work to be done on this subject; thank you, regit.

 

[foto_fool]

I have been thinking about this thread in my sleep. I believe that "bokeh" has been construed to be an intrinsic property of any particular lens. I begin to question this.

Reviewing my own representative photos - I'm no pro, so we are only talking in the low three digits here - I note that on the same roll of film with the same lens, some images seem to have pleasing bokeh while in others the OOF is jarring and distracting.

It occurs to me that "good" or "bad" bokeh depends less on how a particular lens generally renders OOF than it does on WHAT is in the OOF field of the frame.

We assume that different lenses will render the same OOF composition differently - I think I am going to have to perform the experiment to prove it to myself.

Unless someone has a good reference link? - John

 

[Kin Lau]

John,

Check out the lens review section of www.rokkorfiles.com . Many of the lens reviews have bokeh comparisons at the same fstop & focal lengths.

 

[clintock]

This page is good-
http://www.vanwalree.com/optics/bokeh.html
The author calls the out of round type of out of focus highlights 'cateye' which I have been calling 'football'. I think cateye is better, since all over the world, cats have similar eyes, but only in the US and Australia is a football not round.

I've been calling the donut-like specular highlights and double lines 'blood cells' but now I can say 'ni-sen'.

In the 35mm format, most lenses over 75mm will probably have good bokeh, and anything less than 28mm will have such depth of field in most shots, that bokeh just won't be all that prominant. It seems the 35mm and 50mm focal length lenses are the ones with the most bokeh debate.
The cat-eyes of the CV 40 1.4 nokton really bug me, but somehow I can live with the ni-sen of the Contax G 35 2 Planar...

 

[foto_fool]

Thanks Kin Lau and clintock - both articles were informative. I just knew that circles of confusion and uncorrected spherical abberation would crop up somewhere in the explanation of OOF highlight rendering. I'm going to go away and study some more, and take some more pictures before I come back to this thread. Maybe later I will have something cogent to contribute.

- John