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Photo Forum / Film Photography / Medium format / March 2004Fewer elements - lesser Bokeh?
I've been experimenting with antique cameras for some time and I've come to a somewhat controversial conclusion, which is based on experience alone. I believe that the fewer elements you have the less "blitzed out" your bokeh is, that is to say the less your main subject stands out from the background. Has anyone else noticed this? Thanks > I've been experimenting with antique cameras for some time and I've come > to a somewhat controversial conclusion, which is based on experience > alone. I believe that the fewer elements you have the less "blitzed > out" your bokeh is, I think it's that many of the 3 element lenses are just have crappy QC and aren't sharp till they are stopped down so they don't give a "3D look. Many multi element lenses have horrible bokeh so that doesn't promise anything. I have a couple of modern cooke triplets that have wonderful bokeh so I don't think this "number of elements" has much to do with it.  SignatureStacey > I've been experimenting with antique cameras for some time and I've come > to a somewhat controversial conclusion, which is based on experience > alone. I believe that the fewer elements you have the less "blitzed > out" your bokeh is, that is to say the less your main subject stands out > from the background. Has anyone else noticed this? Yes. The fewer elements, the more you have to stop down to get adequate sharpness in the plane of focus. This results in less blitzed out backgrounds in actual use. This applies to 3 element lenses vs. Tessars vs. Planars. But I suspect that the number of blades in the iris makes more of a difference than lens design. David J. Littleboy Tokyo, Japan > But I suspect that the number of blades in the iris makes more of a > difference than lens design. But background blurring's most striking at the widest aperture, when the number of aperture blades doesn't matter. > > But I suspect that the number of blades in the iris makes more of a > > difference than lens design. > > But background blurring's most striking at the widest aperture, when the > number of aperture blades doesn't matter. True, but you can't use a 3 or 4 element lens wide open if you care about sharpness. And even the best of modern lenses improve a bit by stopping down. David J. Littleboy Tokyo, Japan > But I suspect that the number of blades in the iris makes more of a > difference than lens design. > > David J. Littleboy > Tokyo, Japan I have to disagree on this point, not that I know the exact difference number of blades have to do with bo-keh... Having used Rolleis for awhile now, the OOF parts of a Xenotar-type lens print is worse than the Tessar-type (Xenar) lens--from my observations. Regardless of aperture (obviously the further stopped down the more in focus :-). But yeah, a Xenotar lens type has worse OOF rendering. Perhaps, worse than most six element lenses I would wager... >> But I suspect that the number of blades in the iris makes more of a >> difference than lens design. [quoted text clipped - 9 lines] > focus :-). But yeah, a Xenotar lens type has worse OOF rendering. > Perhaps, worse than most six element lenses I would wager... And I have two different 80mm 6 element lenses for my Kiev, one has nice smooth bokeh and the other doesn't and both have the same number of blades in the iris. I have a tessar clone 300mm LF lens that has nasty "clumpy" bokeh and the diaphram has what looks like 50 blades! My 3 element 210mm geronar has nice bokeh and 1/4 the number of blades and 1 less element. The 300mm heliar has nice bokeh again with like 50 blades so I know in this case it's the lens design not the number of elements or number of blades. I don't think the # of blades is a big deal unless it has a really low number of them, like 5 or less. Even then it's more likely to just show up as "diaphram flare" rather than effect the bokeh. My old olympus XA only has 2 blades and it works pretty good! :-) Almost any of the older folder lenses will have a bunch of blades so I doubt that is the cause for the OP's -problem-. More likely it's that the "low number of elements" lenses are on low end models and used crappy glass/poor designs/low QC etc. SignatureStacey > I don't think the # of blades is a big deal unless it has a really low > number of them, like 5 or less. Even then it's more likely to just show up > as "diaphram flare" rather than effect the bokeh. That's what I was talking about: my Fuji GS645S has a 5-bladed diaphragm, and OOF areas with bright spots in them are really gross. Sigh. > Almost any of the older folder lenses will have a bunch of blades so I doubt > that is the cause for the OP's -problem-. More likely it's that the "low > number of elements" lenses are on low end models and used crappy glass/poor > designs/low QC etc. Could be. I'm quite pleased with bokeh on all the Mamiya 645 lenses I've got, so other than the Fuji, it's not a problem here. David J. Littleboy Tokyo, Japan > Could be. I'm quite pleased with bokeh on all the Mamiya 645 lenses I've > got, so other than the Fuji, it's not a problem here. > > David J. Littleboy > Tokyo, Japan The thing I remember reading was that 'the less aberration a lens has the better the bo-keh'... But the interesting thing that I've noticed is that most of the Xenotar-type lens designs have this, quite bad, OOF rendering, interesting because it obviously (to anyone who's used one IMO) has better correction to any Tessar-type design. Even a macro lens with floating elements with a Xenotar-type lens design has a similar type of bad OOF IMO (difficult to describe, but similar to a mirror lens doughnut but less severe at the 5.6 apertures)--the macro lens I'm talking about is a 50mm 3.5 Zuiko. A 3.5 55mm Nikkor is of the same design and according to one other (that I can name) has the same type of OOF rendering. So, my conclusion is that all Xenotar-type lens designs have this particular rendering... Stacey, however, has a different opinion (I think, sophisticated) to this and, perhaps, the matter seems unresolved (probably forever). > > Could be. I'm quite pleased with bokeh on all the Mamiya 645 lenses I've > > got, so other than the Fuji, it's not a problem here. [quoted text clipped - 13 lines] > opinion (I think, sophisticated) to this and, perhaps, the matter seems > unresolved (probably forever). I tend to be closer to the "bokeh schmokeh" camp, except for the egregious cases, so playing with some alleged bad-bokeh high end lenses is tempting. There's a Rolleiflex 2.8D Xenotar over at KEH for $499. Maybe I should buy it and see for myself. The problem with that is that I'm likely to turn into a pathological Rollei collector. There's no way I'm letting my mid-50's 3.5 Tessar go (I really like the weight and workmanship), but I'd like at least one high-end Zeiss lens on hand for comparison, but the later f/2.8 Rolleis are heavy clunky cameras, and outrageously expensive. So what I'd really like, I think, is a recent 3.5 Planar. (I understand that the Planar design went through some changes and that the later ones are noticeably better.) But people claim the Xenotar's just as good. All very academic, since I prefer either 55mm or 110mm to 80mm<g>. David J. Littleboy Tokyo, Japan > I tend to be closer to the "bokeh schmokeh" camp, except for the egregious > cases, so playing with some alleged bad-bokeh high end lenses is tempting. [quoted text clipped - 12 lines] > David J. Littleboy > Tokyo, Japan The latest Rolleis are rather pretty, in the same way as the new VW bug. From what I've read, there appears to be more acclaim for the Xenotar than the Planar, at least among those who've used both. Perhaps that was for the 3.5 Rolleis. David, as someone who lives in Japan with all those beautiful photo mags, Leica fetishists, and bokeh connoisseurs, do you read enough Japanese to get a sense of the differences in gearhead culture there? I mean compared to the U.S. or Western 'advanced amateur' crowd. And is Fujiya camera still around? > David, as someone who lives in Japan with all those beautiful photo mags, > Leica fetishists, and bokeh connoisseurs, do you read enough Japanese to get > a sense of the differences in gearhead culture there? I mean compared to the > U.S. or Western 'advanced amateur' crowd. Hmm. I read Japanese well enough to read what I want to read (MA in East Asian Studies, 15 years as a professional translator), but it's still slower going than English so I don't play on mailing lists here. The pretty magazines are pretty: as I've mentioned before, Natural Glow is a lovely B&W magazine that has a firm grasp on the viscereal beauty of B&W imaging with _none_ of the pretentions to art of Lens Work or Aperture. (Although I don't like the photos in either of the two main magazines.) I think, in the end, it's quite similar. Japan is perhaps a bit more name-brand silly (Leica and Zeiss are seriously expensive here) than the west, but it's a matter of degree. I don't have a feel for the amateur MF community here at all: 35mm and digital is all I see on the street in regular folks hands. If it's MF, it's clearly a professional shoot. (But the amateur landscape shots in the landscape magazines are often MF. (Within the last year, the bimonthly landscape magazine has started talking about using digital for landscapes.)) The biggest difference is that 25% of the population being in the Tokyo area, there are used equipment stores by the dozen, but no ebay. (Japan is the only country where ebay flopped.) Vying for top place with urbanization, though, is the simple fact that "bokeh" is just another technical term, and isn't controvertial at all<g>. > And is Fujiya camera still around? Yep. It's one of the main used stores, and where I bought my 110/2.8 Mamiya 645 lens. David J. Littleboy Tokyo, Japan Bokeh is what I looked like after my mate realized I forgot it was St. Patrick's day. Why? Why, my mate is the one and only Molly McGuire. I kid you not. Worse than forgetting an anniversary to ignore St. Pat's day. Bokeh! Ni san bokeh! (or, "me lad, ye look like a lorry run over you you do.") > I tend to be closer to the "bokeh schmokeh" camp, except for the egregious > cases, so playing with some alleged bad-bokeh high end lenses is tempting. Yeah, I agree, bokeh isn't something I'm usually looking for, it's usually what is in focus ;-) > There's a Rolleiflex 2.8D Xenotar over at KEH for $499. Maybe I should buy > it and see for myself. The problem with that is that I'm likely to turn into [quoted text clipped - 6 lines] > But people claim the Xenotar's just as good. All very academic, since I > prefer either 55mm or 110mm to 80mm<g>. I've owned (and used =) quite a number of lens types for the Rollei and the 3.5 Planar is indeed a lovely lens. My one was the five element design. Just amazing, then again the lens I liked using and miss the most was the 2.8 Xenotar. And you know, the 2.8 Planar is no slouch either... A properly aligned and adjusted 'Flex is probably going to _still_ going to be a good camera to use. The lens I really enjoy using is 'Cord Xenar on a Va (ll). Just a good simple and light camera to use with a good lens on it. I figure something that old is better simpler, that way less to go wrong and (potentially) less to repair (fingers crossed). If I was you (in Japan) I'd be going gaga over all of those fantastic Fuji Rangefinders. The big ones perhaps a 6x8 (cool format)... >> I tend to be closer to the "bokeh schmokeh" camp, except for the >> egregious cases, so playing with some alleged bad-bokeh high end lenses >> is tempting. >> > Yeah, I agree, bokeh isn't something I'm usually looking for, it's > usually what is in focus ;-) Bokeh isn't a big deal at all; until you shoot something really nice but for some reason the OOF background is so distracting it's pulls you eye to that instead of the in focus subject! SignatureStacey > Bokeh isn't a big deal at all; until you shoot something really nice but for > some reason the OOF background is so distracting it's pulls you eye to that > instead of the in focus subject! Actually, that's the best summation, methinks. I had a Novar/Ikonta and though sharp stopped down to f/11, wide open it's out-of-focus rendering was a target shape behind my isolated subject. It was EXTREMELY distracting in several pictures, so I didn't find the camera as useful as I'd have liked. I now have a Tessar on an Ikonta (40$, Best Camera Buy This Year) which has a much more pleasing rendition when shooting in the evening light- trees don't have a horribly circular smudge look, at least nearly as much. Then again, I don't overmuch like the out of focus rendition of the Tessar, either, but stopped down past f/5.6, I don't notice it. >> Bokeh isn't a big deal at all; until you shoot something really nice but >> for some reason the OOF background is so distracting it's pulls you eye >> to that instead of the in focus subject! > Then again, I don't overmuch like the out of focus rendition of the > Tessar, either, but stopped down past f/5.6, I don't notice it. The tessar bokeh isn't awful but isn't the best either. Someone described it as "clumpy" which seems to fit. The heliar is much better bokeh wise but isn't as sharp stopped down either IMHO. SignatureStacey > There's a Rolleiflex 2.8D Xenotar over at KEH for $499. Maybe I should buy > it and see for myself. The problem with that is that I'm likely to turn into > a pathological Rollei collector. I think it's the C you're after, that's the one with the 10 bladed diaphragm :-) (or so I've been told)...<g> I used to have one, didn't notice it (the diaphragm)... Got hacked off with the shutter speeds however (pedantic).... > > There's a Rolleiflex 2.8D Xenotar over at KEH for $499. Maybe I should buy > > it and see for myself. The problem with that is that I'm likely to turn into [quoted text clipped - 4 lines] > I used to have one, didn't notice it (the diaphragm)... Got hacked off > with the shutter speeds however (pedantic).... What was wrong with the shutter speeds? I saw a 3.5F Planar in a Japanese magazine today: US$2,000. Ouch. No Rolleis purchased in Japan for me. David J. Littleboy Tokyo, Japan > What was wrong with the shutter speeds? They 1,2,5,10,25,50,100,200... or something along those lines > So, my conclusion is that all Xenotar-type lens designs > have this particular rendering... I'm going to assume that Xenotar means double-Gauss. Its true that many double-Gauss designs have poor wide-open bokeh due to the way low order spherical aberration is balanced with high order spherical aberration. But to make a general conclusion is clearly wrong. For example, the original Vivitar Series 1 90mm macro lens is a double-Gauss design with exceptionally good bokeh since it has just the right amount of uniformly undercorrected spherical aberration. Brian www.caldwellphotographic.com >>So, my conclusion is that all Xenotar-type lens designs >>have this particular rendering... > > I'm going to assume that Xenotar means double-Gauss. Not quite... A Xenotar-type design is 5/4 and not symmetrical as you have me believe... Here is a link to give you a better idea: http://www.star.ucl.ac.uk/~rwesson/esif/om-sif/lensgroup/50mmf35.htm However, it is a relative of the (generic) Gauss--type, not that that was what I was talking about. > But to make a general conclusion is clearly wrong. You can make all the assumptions you want too. That I make a conclusion about anything is my own business whether you like it or not. This particular conclusion is one based on observation of a particular lens type over some time... blah blah... It is also an area very subjective relative unimportance, but something I finding interesting, and if it is wrong--fine, prove it... But not with your (wrong) assumptions and generalisations about what I am talking about. > For > example, the original Vivitar Series 1 90mm macro lens is a > double-Gauss design with exceptionally good bokeh since it has just > the right amount of uniformly undercorrected spherical aberration. I cannot find the lens diagram of the lens you mention here but I assume it is not what I'm talking about (do I have to mention it again... not talking about the generic ie symmetrical 6/4 double-Gauss design)... The lens-type I am talking about has 5 elements in 4 groups and there are three versions of this lens I am interested in (and have been discussing, so far, here), the original Schneider design, the Zuiko Macro 50mm F3.5 and the Nikkor 55mm Macro F3.5 And yes the Xenotar-type lens is one defined by Nikon as a lens 'type' in it's own right, but also happens to be a relative of those lens types you mention... > >>So, my conclusion is that all Xenotar-type lens designs > >>have this particular rendering... [quoted text clipped - 3 lines] > Not quite... A Xenotar-type design is 5/4 and not symmetrical as you > have me believe... _SNIP_ Nicholas: Double-Gauss designs come in a very wide variety of subtypes, and it wasn't clear to me whether you were referring to the general design form or to the particular 5/4 subtype. So, if you want to restrict the conversation to the 5/4 type, then its OK with me. Xenotars have a degree of symmetry very similar to other double-Gauss designs. The fact remains: a 5/4 Xenotar subtype need not have harsh bokeh. The reason for this is that the design flexibility is nearly as great as with the more complex double-Gauss forms. A competent lens designer can vary the character of the defocused background highlights at will. For example U.S. Patent 2,844,072 by Lowenthal discloses an f/2.8 Xenotar type lens with moderate undercorrected spherical aberration. This design will produce beautifully soft-edged defocused background highlights. Although Schneider adopted the Xenotar type fairly early, the design was pioneered by Charles Wynne of Wray Optical back in the 1940's. At the time it was hailed as a significant achievement since it was apparently simpler than the similar 6/4 Gauss type. Oddly enough, the reason that the 5/4 Xenotar design form isn't used more widely is that it is more difficult to make and hence more expensive than the more common 6/4 form. The thickness tolerance on the 4th element almost always turns out to be unusually tight, and this element is also quite difficult to center. The formula for the Vivitar Series I 90mm macro lens is given in U.S. Patent 3,942,875 (example 6 of 6). There are a couple of minor typos in the prescription, and I can give you the correct version if you're interested. As you guessed, this design is not a Xenotar derivative since the rear shell is a cemented doublet. However, changing that cemented doublet to a singlet is easier than you might imagine. Brian www.caldwellphtographic.com > I've been experimenting with antique cameras for some time and I've come > to a somewhat controversial conclusion, which is based on experience > alone. I believe that the fewer elements you have the less "blitzed > out" your bokeh is, that is to say the less your main subject stands out > from the background. Has anyone else noticed this? > Thanks I have several folders, and I do notice an overall smoothness to the backgrounds. However, I think it might be the lack of contrast, and overall softness of rendition. Stopping down helps, or push processing the film to bump the contrast up. Sometimes filters can help a bit as well. Another guess is that there is more spherical aberration in a triplet lens design. The flaws in ancient designs might actually help some aspects of the images. Some of these designs work nicely for portraits. Ciao! Gordon Moat Alliance Graphique Studio <http://www.allgstudio.com I don't know about bokeh, but the number of elements definitely has an effect on flare. Large zooms, with their many elements, are particularly subject to flare, despite multicoating. Moreover, the flare gets smeared out more generally and degrades the picture more as you increase the number of elements. For single focal length lenses, elements are usually added to better correct the aberations. Up to six elements or so, coating seems to work well to control the flare. Someone posted that the 5 element Heliar design was especially designed to give a smooth bokeh. > I've been experimenting with antique cameras for some time and I've come > to a somewhat controversial conclusion, which is based on experience > alone. I believe that the fewer elements you have the less "blitzed > out" your bokeh is, that is to say the less your main subject stands out > from the background. Has anyone else noticed this? > Thanks > I've been experimenting with antique cameras for some time and I've come > to a somewhat controversial conclusion, which is based on experience > alone. I believe that the fewer elements you have the less "blitzed > out" your bokeh is, that is to say the less your main subject stands out > from the background. Has anyone else noticed this? > Thanks No.My folder camera (Bessa II with 105/3,5 color-heliar 5 elements with multilayer color)have a best wonderful bokeh in the world.Seriously. Hy Germano > > I've been experimenting with antique cameras for some time and I've come > > to a somewhat controversial conclusion, which is based on experience [quoted text clipped - 6 lines] > with multilayer color)have a best wonderful bokeh in the > world.Seriously. Shouldn't you be more concerned with what the stuff IN FOCUS looks like? >> > I've been experimenting with antique cameras for some time and I've >> > come to a somewhat controversial conclusion, which is based on [quoted text clipped - 10 lines] > > Shouldn't you be more concerned with what the stuff IN FOCUS looks like? Not realy. For many subjects the out of focus area is as important as the in focus subject. But then again people who are -addicted- to autofocus zooms and digicams have never seen the bokeh a lens like a sonar or a heliar can produce. SignatureStacey > > > I've been experimenting with antique cameras for some time and I've come > > > to a somewhat controversial conclusion, which is based on experience [quoted text clipped - 8 lines] > > Shouldn't you be more concerned with what the stuff IN FOCUS looks like? Have you ever seen a folder get anything in focus? David J. Littleboy Tokyo, Japan > "Randall Ainsworth" <rag@nospam.techline.com> wrote in message >> >> Shouldn't you be more concerned with what the stuff IN FOCUS looks like? > > Have you ever seen a folder get anything in focus? Have you ever used one? My Tessar Ikonta and other rangefinder models I have don't seem to have any problem. Maybe the ones you've used (If you ever have) were out of adjustment? SignatureStacey Nikon has addressed variable "bokeh", aka: Defocus Control. See this: http://www.nikon.co.jp/main/eng/photo_world/kumon/06e.htm Sharp, a lot of elements, intentional defocus-control. > > I've been experimenting with antique cameras for some time and I've come > > to a somewhat controversial conclusion, which is based on experience [quoted text clipped - 6 lines] > with multilayer color)have a best wonderful bokeh in the > world.Seriously. Erwin Puts, the noted Leica specialist, has published the following observations about Bokeh: "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. So bokeh might be detectable in older Leitz lenses, but this is not a design decision, just the result of the overall correction. Modern lenses indeed have less bokeh as I understand the idea, they are corrected to a much higher degree than older Leica lenses." Contrast that with what Carl Zeiss says in their brochures--something to the effect that Zeiss lenses have the most beautiful bokeh of all lenses . . . One company makes no attempt to optimize bokeh while another company designs their lenses with bokeh in mind. Go figure . . . Puts does make one statement that puts this all in perspective: "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." Finally, Bob Monaghan's Super Site notes that, on blind tests, people have been unable to tell which brand of lens produced which negative. I can't help but wonder how much of these elusive lens characteristics are really detectable, and how much of it is in our own minds. One thing is apparent--the photographer is much more critical of these factors than is the person that is viewing the image. He is almost always more concerned with things like composition, exposure and subject matter, rather than being critical on the out-of-focus areas. > Finally, Bob Monaghan's Super Site notes that, on blind tests, people have > been unable to tell which brand of lens produced which negative. There was recently a "blind test" of shots done with a 150mm f2.8 FSU and a 180mm f2.8 sonar on the kievreport and most people were able to pick the sonar shots out from the bokeh and the FSU lens has pretty nice bokeh itself. Maybe the "uneducated" public can't tell? I picked the sonar shots out 6 out of 6. SignatureStacey as JJS noted, Nikon and others have produced defocus control lenses specifically to control the out of focus effects of these lenses (135mm DC etc.), which act largely thru under or over corrected spherical aberrations (depending on whether you want the OOF effects in front of the subject (rarer, e.g., leaves in front of subject) or behind the subject. So bokeh effects can be subject to control and modulation by designers ;=) This doesn't eliminate the potential of other aberrations smearing light distributions (esp. behind the subject) in interesting and pleasing ways. Nor does it guarantee that some lenses will produce more pleasing bokeh results because they are out of alignment etc. more than others of the same kind or design ;-) Sometimes, bad lenses are good ;-) I agree with Stacey and others that the three element lenses, with less degrees of correction available, and lower cost, often had more pleasing bokeh, possibly due to more spherical aberrations being in the lens than a more corrected more elements optic. Similarly, many of the worst bokeh lenses are the highly optimized lenses (e.g., zooms). This has encouraged me and others to look again at older out of favor lenses which may be "bad" in a good way - i.e., have good bokeh ;-) grins bobm Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* Bokeh can indeed be distracting in a photo and unless you never take anything but 0 to infinity in focus photos, it sometimes must be taken into account. It is a function of lens design but not necessarily related to quality. Some very fine lenses have "bad" bokeh. It has been used as a topic of comparison between Japanese(read Nikon) and Leitz lenses in the past for instance. If you have ever noticed a split or double image effect in an oof area(such as in trees branches or window bars etc) then you have seen what usually is termed as bad bokeh. The best example of bad bokeh I can think of is the old Novoflex 400 f/5.6 lens. It is a fantastic lens for it's intended purpose and as sharp as anything you will see bar none. But... busy oof backgrounds become even busier due to split bokeh. There was an article in Photo Techniques some time ago, I believe, that had a very complete explanation of what determined the bokeh of any particular lens. The most highly corrected lenses were often not very good in that respect. D >>steven.sawyer@banet.net wrote in message > [quoted text clipped - 61 lines] > more concerned with things like composition, exposure and subject matter, > rather than being critical on the out-of-focus areas. > Erwin Puts, the noted Leica specialist, has published the following > observations about Bokeh: etc., etc., . . . . Jeremy, you can believe whatever you want, but if you choose to believe all of the stuff that Puts writes then you will only be mislead. Erwin Puts is no lens designer, as the passage you quote makes quite clear. While its true that many lens designers have no clue what bokeh is, this is certainly not universally true. How else could you explain lenses like the 105mm and 135mm DC Nikkors? Also, near the optical axis, the *only* aberrations possible in a rotationally symmetrical optical system are spherical aberration and axial chromatic aberration. Chromatic aberration just doesn't help at all in achieving good bokeh. Lenses with excellent bokeh have slightly undercorrected spherical aberration throughout most or all of their image field. Brian www.caldwellphotographic.com > > Erwin Puts, the noted Leica specialist, has published the following > > observations about Bokeh: [quoted text clipped - 7 lines] > clue what bokeh is, this is certainly not universally true. How else > could you explain lenses like the 105mm and 135mm DC Nikkors? Just to add a little to this, it does seem that the 105 mm f2.5 was designed specifically with a consideration of defocus rendition. There is a nice article about these considerations, and the engineering at: <http://www.nikon.co.jp/main/eng/society/nikkor/n05_e.htm> > Also, > near the optical axis, the *only* aberrations possible in a [quoted text clipped - 3 lines] > slightly undercorrected spherical aberration throughout most or all of > their image field. There is a mention in the above article that a switch from a Sonnar type design to a Xenotar type design improved aberration correction. While this makes sense to me, is that what effected the reduction in Coma? Would that reduction in Coma directly relate to improvements in defocus rendition? Thanks! Ciao! Gordon Moat Alliance Graphique Studio <http://www.allgstudio.com > >While its true that many lens designers have no > > clue what bokeh is, this is certainly not universally true. How else [quoted text clipped - 7 lines] > > slightly undercorrected spherical aberration throughout most or all of > > their image field. Puts does state in his article that he differs with most others in believing that Bokeh is not a conscious design decision. I've never used Leica lenses, so I can offer no qualified opinion on that point. I tend to disagree with Puts, on this point. Some lenses are known for their creamy Bokeh, and I find it hard to believe that this result was an accident. In the case of my own SMC Takumar (Pentax screw-mount) lenses, editor Mike Johnston published an article explaining its exceptionally good Bokeh. Apparently Pentax followed the design of Carl Zeiss. Here is what Johnston saya about the SMC Takumar 50mm f/1.4 normal lens: "All these lenses are classic Planar designs, as are more or less every fast 50mm except for the Leica M lens, which is an idiosyncratic design unique to Leica; but where most makers have economized by making the surfaces between the fourth and fifth elements flat, Pentax has always stuck with the original design and used cemented spherical surfaces there. Aside from being more expensive to manufacture, this results in a lens that is slightly less sharp at infinity in the plane of focus, but that has better off-axis aberration correction and thus, better bokeh or blur." I've never thought of my lenses as being appreciably less-sharp than others. And Zeiss apparently still uses this formula in their Planar designs, and I don't recall ever hearing anyone question THEIR reputation for sharpness. From what I've read, the newer FA (Limited) series from Pentax uses an entirely different design. Apparently the lenses have improved sharpness rendition, while not compromising Bokeh. I don't know much else about the design. Perhaps someone more knowledgeable can fill us in. (Of course, the lenses I've discussed are not MF, but the Planar design is offered in both 35mm and MF). Puts does seem to be accurate when he says that Bokeh MIGHT be measured scientifically but no one knows how and thus the subjective interpretations abound. In spite of that, I know good bokeh when I see it, and I suspect most other photographers do, too. > . . . . . . > > Puts does state in his article that he differs with most others in believing > that Bokeh is not a conscious design decision. I've never used Leica > lenses, so I can offer no qualified opinion on that point. Well, I have, and I tend to like the wide open rendition of the older lenses more than the newer ones. Maybe that means the newer ones are overcorrected, though they are sharper, and capable of somewhat higher resolutions. > I tend to disagree with Puts, on this point. Some lenses are known for > their creamy Bokeh, and I find it hard to believe that this result was an > accident. . . . . . Perhaps with some strictly computer designed newer lenses it could be an accident. Without hearing from the engineer responsible, it would be tough to tell. That is one nice aspect of the Nikon articles I mentioned (there are more than just for the 105 mm f2.5). > . . . . . . > > I've never thought of my lenses as being appreciably less-sharp than others. Probably not enough difference in results from hand held shots to see a difference. With tripod shots . . . maybe . . . . . > And Zeiss apparently still uses this formula in their Planar designs, and I > don't recall ever hearing anyone question THEIR reputation for sharpness. One thing that is amazing (to me at least) is seeing so many variations on Zeiss designs. Obviously, start with a known good idea, and modify it, chances may be better of getting a good result. > From what I've read, the newer FA (Limited) series from Pentax uses an > entirely different design. Apparently the lenses have improved sharpness [quoted text clipped - 3 lines] > (Of course, the lenses I've discussed are not MF, but the Planar design is > offered in both 35mm and MF). You might find that some large format lenses were also Planar designs. > Puts does seem to be accurate when he says that Bokeh MIGHT be measured > scientifically but no one knows how and thus the subjective interpretations > abound. The best I have read on that so far, is that the nearness of the sagital and tangential curves on an MTF chart could indicate nice defocus rendition. The other thing I have heard is to look at the taper of the curve, and that a slower taper could be better. Of course, an MTF chart is only a starting point; using a lens under the conditions you intend to use it will give a better indication. Some designs change quite a bit with distance of focus, while others tend to not handle high contrast defocus areas well . . . basically many variables. Probably many of us have tried supposedly great lenses, and found a condition when the results were much worse than we expected. > In spite of that, I know good bokeh when I see it, and I suspect most other > photographers do, too. Mostly, I have picked and chosen the lenses I currently use for work. I have definitely had some unacceptable lenses in the past, though luckily those have been rare exceptions. Going back to the original poster, it is interesting that some of the simpler designs do so well with defocus areas. Ciao! Gordon Moat Alliance Graphique Studio <http://www.allgstudio.com The "creamiest" bokeh I've been able to obtain was with a "dimeniscus" arrangement i.e. a meniscus lens with a diopter in front. I would consider this to be a very "accidental" design. However, with a single meniscus arrangement, even the focusing variant e.g. Goertz Frontar, I've been unable to duplicate this effect. Although the "bokeh" I obtained with a dimeniscus arrangment was super creamy, the background was not as "blitzed" out as what you'll find with five or more element designs. > Some lenses are known for > their creamy Bokeh, and I find it hard to believe that this result was an > accident. see the http://medfmt.8k.com/mf/soft.html pages on soft lenses; there is a +10 (100mm) single element diopter lens used in a focusing mount as a soft lens, often also praised for its bokeh too ;-0) dimeniscus - ;-) now I have another lens combo to try - thanks for the suggestion ;-) regards - bobm Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* > see the http://medfmt.8k.com/mf/soft.html pages on soft lenses; there is a > +10 (100mm) single element diopter lens used in a focusing mount as a soft > lens, often also praised for its bokeh too ;-0) Here's one: http://WIND.WINONA.EDU/~stafford/MYSTERY-LENS/ that still has me stumped. The soft-focus is on the rear. Strange. > Here's one: http://WIND.WINONA.EDU/~stafford/MYSTERY-LENS/ that still has > me stumped. The soft-focus is on the rear. Strange. What a pretty lens! Have you used it? SignatureStacey > > see the http://medfmt.8k.com/mf/soft.html pages on soft lenses; there is a > > +10 (100mm) single element diopter lens used in a focusing mount as a soft > > lens, often also praised for its bokeh too ;-0) > > Here's one: http://WIND.WINONA.EDU/~stafford/MYSTERY-LENS/ that still has > me stumped. The soft-focus is on the rear. Strange. A lens for a 8x10" wooden box camera. That you must know already. The rear setting for soft focus is actually quite easy to access, when the glass isn't in place. The photographer must have previous experience about where to set it, because it isn't accesible in real time during focusing. Out of curiosity I fed Google the incantation "mullett bros photo kansas" and got one hit with minor relevance: http://www.rootsweb.com/~nedawson/whowho/whowhodc2.htm . A photographer called Marshall E. Hebrew worked there in 1918-19, which seems like the same period as the lens. -- Lassi > Here's one: http://WIND.WINONA.EDU/~stafford/MYSTERY-LENS/ that still has > me stumped. The soft-focus is on the rear. Strange. Beautiful lens! The engraved information says that it's an f/5 lens, yet the aperture ring has an f/4 setting, or have I misread something? James Meckley > Beautiful lens! The engraved information says that it's an f/5 lens, > yet the aperture ring has an f/4 setting, or have I misread something? Good eye, James. It is more mysterious than that. See this - it is the right side of the dial: http://wind.winona.edu/~stafford/2.jpg (Sorry four the lousy underexposed picture, but I just snapped it by the window as the sun had about set.) So the lens is marked "F5" in one place and the widest aperture "1,5". (The barrel and lens are not mismated. They are as much a single part as one can imagine.) I'm going to take a guess that the "1,5" is European decimal notation. Could the lens be "1,5" under a the manufacturer's convention, but branded "F5" to follow the American standards by the American distributor? Stranger and stranger! > > Beautiful lens! The engraved information says that it's an f/5 lens, > > yet the aperture ring has an f/4 setting, or have I misread something? [quoted text clipped - 8 lines] > one can imagine.) I'm going to take a guess that the "1,5" is European > decimal notation. No. We Europeans have always used the f-value as it is. I'm not sure when it was adopted, but possibly already in the 17th century when the first telescopes were built. > Could the lens be "1,5" under a the manufacturer's convention, but branded > "F5" to follow the American standards by the American distributor? > > Stranger and stranger! Yes... -- Lassi > [...] We Europeans have always used the f-value as it is. I'm not sure > when it was adopted, but possibly already in the 17th century when the > first telescopes were built. Okay, if you say so, but there were other aperture metrics in the USA and possibly elsewhere. I do not mean the EV marks on some lenses, but something else entirely. For example, I find it hard to believe the lens in question really has an F 1:1.5 aperture. > > [...] We Europeans have always used the f-value as it is. I'm not sure > > when it was adopted, but possibly already in the 17th century when the [quoted text clipped - 4 lines] > something else entirely. For example, I find it hard to believe the lens > in question really has an F 1:1.5 aperture. Wasn't the lens made in Kansas :-) Do you know for certain that the numbers are f-stops? Maybe the maker had developed a system that indicates how long the exposure time is when compared to some standard lens. If the reference lens is an f/4, this lens (f/5) would then need 1.5 times that time when fully open, etc. Should be testable with an exposure meter. -- Lassi > see the http://medfmt.8k.com/mf/soft.html pages on soft lenses; there is a > +10 (100mm) single element diopter lens used in a focusing mount as a soft > lens, often also praised for its bokeh too ;-0) I have one of those weird lenses, the SIMA Soft Focus 100 mm. Basically, everything in the image is blurry, even on the smallest Waterhouse stop. Called it nice defocus rendition is only practical if you acknowledge that the entire image is defocused. Ciao! Gordon Moat Alliance Graphique Studio <http://www.allgstudio.com I belive "dimeniscus" is a term Kodak used to use for their "portrait" box cameras that used a second meniscus lens for close ups. If you just put a diopter in front of a meniscus lens, you'll get the same results, although getting the right focus can only be done by inspection. I use measuring tape for this purpose. > see the http://medfmt.8k.com/mf/soft.html pages on soft lenses; there is a > +10 (100mm) single element diopter lens used in a focusing mount as a soft [quoted text clipped - 9 lines] > * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * > ********************Standard Disclaimers Apply************************* > There is a mention in the above article that a switch from a Sonnar type design to a Xenotar type design improved > aberration correction. While this makes sense to me, is that what effected the reduction in Coma? Would that reduction > in Coma directly relate to improvements in defocus rendition? Thanks! > > Ciao! Gordon: Coma correction for a single object distance is a trivial task with either the Sonnar or double-Gauss (Xenotar) design forms. However, since the double-Gauss has a greater degree of symmmetry the coma correction remains stable over a wider magnification range. The old Nikon 135mm f/2 AI/AIS is an example of a Sonnar type design which is degraded by coma at close focusing distances, but which is very well corrected for all aberrations at small magnifications. Brian www.caldwellphotographic.com > > There is a mention in the above article that a switch from a Sonnar type design to a Xenotar type design improved > > aberration correction. While this makes sense to me, is that what effected the reduction in Coma? Would that reduction [quoted text clipped - 7 lines] > since the double-Gauss has a greater degree of symmmetry the coma > correction remains stable over a wider magnification range. Thanks for the awesome reply, I think I am finally understanding these lens types more. Since the Planar type seems to be quite common in medium format choices, how does that fit in? > The old > Nikon 135mm f/2 AI/AIS is an example of a Sonnar type design which is [quoted text clipped - 3 lines] > Brian > www.caldwellphotographic.com Since you bring up the close focusing issue, it makes me wonder why Nikon did not apply their close range correction (CRC) idea to the 135 mm. If I remember correctly, one group between the aperture and film plane moved. While the construction of the 135 mm you mentioned might not allow that to work, I notice that the 85 mm f1.4 did employ CRC. Perhaps cost was an issue. Ciao! Gordon Moat Alliance Graphique Studio <http://www.allgstudio.com > Since you bring up the close focusing issue, it makes me wonder why Nikon > did not apply their close range correction (CRC) idea to the 135 mm. If I > remember correctly, one group between the aperture and film plane moved. > While the construction of the 135 mm you mentioned might not allow that to > work, I notice that the 85 mm f1.4 did employ CRC. Perhaps cost was an > issue. Several high end lenses do have designs (floating elements) where multiple elements are moved when focusing to help closeup performance. My zuiko 28mm f2, 50mm f2 and their 90mm f2 macro come to mind. The were all cost over $700 20 years ago. I'm sure there are others as well made by other manufacturers. Cost is exactly why they don't do this more as it makes the mechanical design of the lens much more complex. SignatureStacey > > Since you bring up the close focusing issue, it makes me wonder why Nikon > > did not apply their close range correction (CRC) idea to the 135 mm. If I [quoted text clipped - 11 lines] > Cost is exactly why they don't do this more as it makes the mechanical > design of the lens much more complex. Olympus seems to have solved the cost issue. Their IS series cameras have an integrated zoom lens that has several lens groups moving around in all directions, and still the whole camera costs far less than $700. -- Lassi Lassi Hippeläinen <lahippel@ieee.orgies.invalid> wrote in message news:<40671408.9B609FF@ieee.orgies.invalid>... > Olympus seems to have solved the cost issue. Their IS series cameras > have an integrated zoom lens that has several lens groups moving around > in all directions, and still the whole camera costs far less than $700. > > -- Lassi Moving groups of elements around is really not very costly in high volume production. I was once involved in a 3:1 zoom lens project in which the complete opto-mechanical package cost less than $15.00. The truth is that mechanical parts are quite cheap. The main difficulty in my experience is getting a first-class mechanical design. Brian www.caldwellphotographic.com > > > There is a mention in the above article that a switch from a Sonnar type design to a Xenotar type design improved > > > aberration correction. While this makes sense to me, is that what effected the reduction in Coma? Would that reduction [quoted text clipped - 10 lines] > Thanks for the awesome reply, I think I am finally understanding these lens types more. Since the Planar type seems to be > quite common in medium format choices, how does that fit in? The double-Gauss design type is a natural choice when you want high image quality and reasonable production economy in a lens with medium to large aperture and moderate field angle. It is markedly superior to Tessars in virtually all respects. Sonnars tend to be preferred for longer focal lengths because they are more compact, and they lend themselves more conveniently to apochromatic correction. > > The old > > Nikon 135mm f/2 AI/AIS is an example of a Sonnar type design which is [quoted text clipped - 9 lines] > the 135 mm you mentioned might not allow that to work, I notice that the 85 > mm f1.4 did employ CRC. Perhaps cost was an > issue. I suspect that the Nikon designers felt that the 135/2 AI design was good enough at the time. It is a very nice lens, and edge performance degradation due to coma even at full aperture and closest focus is still not what I would call dreadful. The later 135/2.0 DC Nikkor is a double-Gauss derivative which does use CRC to control coma in a manner very similar to the 85/1.4. Note that alot of the wide angle Nikkors have CRC, but here the motivation is to keep astigmatism under control while focusing rather than coma. > Ciao! > > Gordon Moat > Alliance Graphique Studio > <http://www.allgstudio.com> Brian www.caldwellphotographic.com > > > > There is a mention in the above article that a switch from a Sonnar type design to a Xenotar type design improved > > > > aberration correction. While this makes sense to me, is that what effected the reduction in Coma? Would that reduction [quoted text clipped - 17 lines] > for longer focal lengths because they are more compact, and they lend > themselves more conveniently to apochromatic correction. Definitely makes sense then why I see so many of each type in their respective ranges. > > > The old > > > Nikon 135mm f/2 AI/AIS is an example of a Sonnar type design which is [quoted text clipped - 17 lines] > The later 135/2.0 DC Nikkor is a double-Gauss derivative which does > use CRC to control coma in a manner very similar to the 85/1.4. Considering that even used, the DC version is quite a bit more than the more normal AI/AIS version, it makes one wonder whether the added cost and complexity really hold many benefits. I have used the 105 mm DC lens once, and it was such a pain (slowing down the pace of shots too much) that I stuck with the more normal 105 mm F2.5 AIS. > Note > that alot of the wide angle Nikkors have CRC, but here the motivation > is to keep astigmatism under control while focusing rather than coma. Very interesting differences. Considering the uses to which the different focal lengths would often be used, I can see why there would be a particular bias in correction. Of course, the more amazing (to me) aspect is that much of that correction work was done several decades ago. Thanks for the information. Ciao! Gordon Moat Alliance Graphique Studio <http://www.allgstudio.com |
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