Let's talk "Bokeh" ...

[regit]

A recent post on PNet got me thinking …

Granted, “Bokeh” or quality of out-of-focus (OOF) area is a subject element in a picture. But by focusing only on a certain aspect of bokeh seems rather limiting to me. While everyone has their own definition of good or bad bokeh, wouldn’t it be useful or at least interesting to try to define a set of vocabulary that describes the elements of bokeh? This way, we can at least ensure that we’re on the same frequency when we talk about bokeh in this forum… so …

Let’s talk Bokeh Let’s start with some basic ones, and hopefully all can chipped in (or change what’s here) to make this more meaningful.

1. Overall bokeh – Encompassed all elements of OOF area that define a look that is appealing to an individual. When talking about overall bokeh, the term “smoothness” often comes up. A fine line can be made between smoothness and pure blur-ness – For example, imagine a 1:2 micro shot of a flower where little can be discerned about the OOF area… are we talking about bokeh or blurness?



2. Specular Highlights – Defines the shapes and density of highlights. Some like it round, some like it funky Density defines the diffusion of the highlights; it can be brighter in the middle but lighter on the outer edges. It can be the other way round (commonly known as “donuts”) and it can be neutral.



3. “Ni-sen” – That’s Japanese for “two lines”. Defines the doublings of (or lack of) edges in OOF areas.



4. In-focus / Out-focus transition gradient – Defines how gradual in-focus plane transits to out-focus plane. It can be linear or it can be abrupt.



5. Foreground and background – General elements of bokeh apply to both OOF foreground and background.



6. OOF Objects’ form – Defines how much form is retained in OOF areas given a certain aperture. Some may still retained enough form to make out what it is, some may not. E.g. people become blobs and trees become dehydrated.



7. OOF Contrast – Defines the amount of contrast present in the OOF areas. It can be strong and it can be light. It can add to a picture or rob the attention away from main subjects.



Ok, that’s all I can think of at the moment, feel free to correct me or chip in

[FrankS]

IMO, I think this is going into too much detail, though I applaud your effort. For example, the transition gradient: that depends on the camera-subject distance and the aperture, nothing else if I understand this correctly. For me, good bokeh (or sofa) means that out of focus picture elements are sympathetic and not distracting from the main subject. Bad bokeh, draws attention to itself and away form the main subject which is in focus.

[bmattock]

I agree with Frank. I also feel it is a noble effort, but too much detail.

[FrankS]

Some people discount bokeh as unimportant, but I don't. It is a factor and I like the idea of trying to describe it, but the best efforts I've seen are the donut highlight spots characteristic of mirror lenses, and the reverberation double image effects of some lenses called nisei-bokeh. (double image)

[regit]

Originally Posted by FrankS

IMO, I think this is going into too much detail, though I applaud your effort. For example, the transition gradient: that depends on the camera-subject distance and the aperture, nothing else if I understand this correctly. For me, good bokeh (or sofa) means that out of focus picture elements are sympathetic and not distracting from the main subject. Bad bokeh, draws attention to itself and away form the main subject which is in focus.

Hi Frank, thank you for the comment. Please don't misunderstand the motive of the post, it is not to define good or bad bokeh, but to build a vocab... Say now, you mentioned that "good bokeh (or sofa) means that out of focus picture elements are sympathetic and not distracting from the main subject", and I ask you to describe those "elements"... what you subsequently described (short of showing me a pic), may or may not be the same "thing" we have in mind...

As for the transition gradient, subject distance and the apeture can change the DOF, but beyond the limits of DOF, the transition is different. E.g. Lux 50 ASPH behave differently in this respect when compared to a non-asph.

[FrankS]

Regit, as I said, I applaud your motive, and wish you success in your goal of expanding the vocabulary of bokeh.

"beyond the limits of DOF, the transition is different. E.g. Lux 50 ASPH behave differently in this respect when compared to a non-asph."

Regit, could you show an example of that? (I don't have the knowledge base to agree or disagree with this.)

"good bokeh (or sofa) means that out of focus picture elements are sympathetic and not distracting from the main subject"

I'm afraid that I cannot be any more precise than this. It is your goal to be able to define vocabulary in order to do so, and I wish you success in doing so.

[regit]

Originally Posted by FrankS

Regit, as I said, I applaud your motive, and wish you success in your goal of expanding the vocabulary of bokeh.

"beyond the limits of DOF, the transition is different. E.g. Lux 50 ASPH behave differently in this respect when compared to a non-asph."

Regit, could you show an example of that? (I don't have the knowledge base to agree or disagree with this.)

"good bokeh (or sofa) means that out of focus picture elements are sympathetic and not distracting from the main subject"

I'm afraid that I cannot be any more precise than this. It is your goal to be able to define vocabulary in order to do so, and I wish you success in doing so.

Thanks again, Frank It is rainning in Perth now, and it is one of those times that one had too much free time Alas, I guess this idea will not take off

As for the difference between ASPH and non-ASPH, I did some test prior deciding on which to keep (I returned the non-ASPH), I'll have to search through my "test neg" and post here... Else, I can run a test with both the ASPH and a Zeiss 50/1.5 at same aperture and same distance. Till then, you can have a look at Jim's test with a 35asph vs non-asph...

http://www.jimarnold.org/galleries/leica_35_test/

[ChrisN]

Hi Regit

To echo Frank, good luck! Not too long ago we touched on this - have a look at my post (#30) in this thread http://www.rangefinderforum.com/foru...ghlight=creamy.

I think bokeh is an area that defies analysis. I'm half-way through a long-delayed re-reading of "Zen and the Art of Motorcycle Maintenance" and this really rings a bell with the discussions of "Quality" and the hip/square, classical/romantic divide. I might drop back a few chapters and read it again with bokeh in mind!

[FrankS]

Chris, unfortunately, the best thing about that book is the title.

regit, I don't want to kill your idea. Let's talk about it more.

[doubs43]

Originally Posted by ChrisN

Hi Regit I think bokeh is an area that defies analysis.

I agree. It would be easier to define Salvador Dali's works.

Bokeh is something I either like, don't like or am indifferent to if it doesn't grab me one way or another. Trying to define bokeh or assign a vocabulary to it seems futile to me...... much like pounding sand.

Walker

[aizan]

i think it just seems futile since nobody has really done much about it. regit's summation of the different aspects is terrific. one picture is worth a thousand words!

[jaapv]

I think Bokeh is like taste: You can write a book full of recipes, but it is impossible to describe the taste of an orange in words.....

[Robin Harrison]

I think regit is to be encouraged in his attempts. Yes, bokeh is hard to define and yes bokeh is subjective, but that is exactly why regit is trying to form some sort of vocabulary! One word 'bokeh' is not enough to describe all the effects we see in o-o-f areas in photographs. I think of the word bokeh as being the 'general impression of out of focus areas' in a photograph. So saying a lens has good bokeh isn't very meaningful.

You couldn't get away with this in other aspects of lens performance. An MTF graph is created by a (usually) well defined procedure that produces an analytical, numeric, and scientific view of lens contrast Vs resolution over the film plane. OK, so it's hard to look at one MTF graph next to other and say that a particular lens is 'better' than the other, but you can say that a particular lens shows greater contrast in an identical situation to another.

Why has no-one attempted to look at bokeh in a methodical way? All 'bokeh tests' I have seen have involved shots of complex scenes with often multiple lightsources and areas of varying amounts of detail. Yes - they are enough to gain a certain impression of out-of-focus performance, but it is hard to translate that into performance in other situations.

I think what is needed are a number of standard tests, and some knowledge about how they relate to real-world performance.

An example would be the "point light source test", which would have a number of variables: lightsource distance, focus distance, lens aperture, lightsource location (in the frame). A particular test might be a point light source in the centre of the frame at a distance of 5m shot against a pure black background. The lens would be focussed at infinity, and an exposure made so that the light source is on Zone IX (I don't really know what I'm talking about here I'm just guessing you don't want to blow out the highlight of the light source, but you want as much information as possible in the rest of the frame). The result would be a single out-of-focus gradient that could be expressed as two distance Vs light graphs, one for the vertical axis, one for the horizontal axis.

One would imagine that a lens with 'smooth bokeh' would record symetrical bell-shaped curves in the above test, where as 'a harsh bokeh lens' would create an undulating or harsh curve.

As well as photographing a lightsouce, one can imagine other tests: a zone 2 area adjacent to a zone 5 area, a zone 5 area adjacent to a zone 9 area, a regular pattern of white on black, concentric circles, etc etc.

This may seem like a lot of complexity, but I think it should be possible to perform six or eight tests that give enough quantitative evidence of how a lens performs in terms of out-of-focus areas. With a little knowedge I think it would be possible to then translate this into an estimation of real-world performance.

You get a lot for 2 cents (well, 1.14 pence) these days

[ChrisN]

Originally Posted by jaapv

I think Bokeh is like taste: You can write a book full of recipes, but it is impossible to describe the taste of an orange in words.....

And yet connoisseurs of fine wines and coffees, for example, have highly-developed vocabularies for communicating what wines and coffees taste like!

[Skinny McGee]

Originally Posted by jaapv

I think Bokeh is like taste: You can write a book full of recipes, but it is impossible to describe the taste of an orange in words.....

Its also hard to rhyme with it.

[kmack]

Originally Posted by Skinny McGee

Its also hard to rhyme with it.

An Orange door hinge?

[jaapv]

I've been told in another thread that bokeh is the Japanese word for confused. I refuse to apply Japanese confusion to German lenses

[Gabriel M.A.]

Originally Posted by jaapv

I've been told in another thread that bokeh is the Japanese word for confused. I refuse to apply Japanese confusion to German lenses

Perhaps they meant to say that they're confused about that Japanese word.
There is no direct translation into English.

Here's the "cornerstone" English language footnote (all literature on the Web eventually point here) by Mike Johnston: http://www.luminous-landscape.com/co...04-04-04.shtml

[Gabriel M.A.]

Originally Posted by regit

are we talking about bokeh or blurness?

A-ha. Lots of people think of both as one and the same. It's hard to debate this point when one of the concepts is already abstract and highly subjective, and inherently shows the other that is indisputable.

To think that wars were started over debates much simpler than that...

[Hugh T]

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

[Robin Harrison]

Originally Posted by Hugh T

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.