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It turned out mine is a black anodized and another black one a friend has is also spot on. Both lenses have earlier serial numbers 36xxxxx like most chrome ones I know. Could it be earlier ones were better calibrated

 

This may have solved a small mystery for me, too. Mine is 38xxxxx and so far has not shown a problem (touch-wood). I think this dates it from around 1997(?) which would be around when I purchased it. I am yet to try it on an M9 though .....

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It turned out mine is a black anodized and another black one a friend has is also spot on. Both lenses have earlier serial numbers 36xxxxx like most chrome ones I know. Could it be earlier ones were better calibrated

 

Sorry typo, both are 37xxxxx. Should't type in the dark without looking at the screen.

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Hmmm

I understood it that focus shift was an accepted fact of life with the 35 'lux, and when all the furious threads happened a couple of years ago it turned out that pretty much all lenses suffered .

 

Which is why later Aspherical designs all include moving elements, and why there is talk of Leica bringing out a new version.

 

Mind you whether it matters (or you notice it) is a different issue.

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Hmmm

I understood it that focus shift was an accepted fact of life with the 35 'lux, and when all the furious threads happened a couple of years ago it turned out that pretty much all lenses suffered .

 

Which is why later Aspherical designs all include moving elements, and why there is talk of Leica bringing out a new version.

 

Mind you whether it matters (or you notice it) is a different issue.

 

I am a certified pixel peeper. So I am pretty sure I would see any noticeable focus shift. I am not saying there isn't any shift, just that the lens may be adjusted at the edge of front focusing wide open, and any shift is covered by the increasing DOF when stopping down.

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Overgaard... you are a reknown expert... but tell me when ever an ELMARIT 35 was made ?

 

Well, for a 2.8 the name "Summaron" was a bit odd, so you could call it Elmarit, but i think this name was only introduced later.

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I am a certified pixel peeper. So I am pretty sure I would see any noticeable focus shift. I am not saying there isn't any shift, just that the lens may be adjusted at the edge of front focusing wide open, and any shift is covered by the increasing DOF when stopping down.

 

HI Alan

Well, I'm not speaking personally, as I've never had one. Of course, careful calibration and practice is going to mitigate, but apart from that I've always felt that focus shift must be a design issue rather than a sample issue. . . . unfortunately I'm notoriously fallable

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HI Alan

Well, I'm not speaking personally, as I've never had one. Of course, careful calibration and practice is going to mitigate, but apart from that I've always felt that focus shift must be a design issue rather than a sample issue. . . . unfortunately I'm notoriously fallable

 

Jono, I think you are absolutely correct that it is a design issue. But the design may not be so bad that careful adjustment won't mitigate (i.e. hide) most of the focus shift as the dof increases.

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Hi all,

 

I went to the dealer this evening and tried both 35mm f2 and f1.4 demo. I finally picked the f2 bcuz F2 should be good enough for most of my pictures and I love its' size. And the price is good !!!

 

tks for all your valuable inputs

 

best

DL

 

P.S. Heading for HK this Thursday 2 weeks for business with my M9 + 35mm f2, either 50mm or 75 mm as my second lens

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It was around 1959 that Leitz lens designations went from being design names (Summar, Summicron) to speed markers pure and simple. The reason was that with computer-aided optical design, a lens design was no longer a master designer's life's work, to be waved triumphantly ever since in front of the prospective purchasers. But while 'Elmarit' was a speed marker from the start (= 2.8), the first Summaron lens was the 3.5cm Summaron 1:3.5 introduced in 1948. At that time, names were designs. And a Summaron was quite literally a modified Summar design, i.e. a symmetrical six-element double-Gauss layout. Hence the name. The 2.8 was a 'stretched' 3.5 so it kept the name even at the late date when it was introduced.

 

Today of course the name of a lens has nothing to do with its interior construction; the recently late 50mm Elmar-M was an exception, dictated by historical piety. I hope this makes the change in Leitz naming policy clear.

 

The old man from the Age of the 5cm Elmar

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Regarding the 35 f/1.4 ASPH and focus shift - it is both a design and adjustment issue.

 

It is a stellar lens for what it does - cover a 35mm FoV @ f/1.4 with very few aberrations, especially in the outer parts of the image; the "field," as some call it. And especially compared to the pre-ASPH version, which turns point light sources into "butterflies" @ f/1.4 off-center - which turn into the "Leica Glow" when they depict something other than point lights. And especially in a size still about 1/4 the volume of a Canon, Zeiss or Leica SLR 35 f/1.4.

 

But it does have some residual spherical aberration (SA) - and that means that wide-open, the light from the edges of the aperture (the extra "f/1.4" light rays) focus at a different point than the f/2.8 rays and the f/16 rays.

 

(Could Leica have designed a "perfect" 35 f/1.4 with no SA? While still improving the edge performance as much as they did? That could make a profit at less than €10,000? I don't know - I'm not a glass-bender.)

 

At any rate, the 35 f/1.4 has some SA. Which means it projects light at f/1.4 as in the top or bottom images here: File:Spherical-aberration-slice.jpg - Wikipedia, the free encyclopedia

 

Stopped down a bit to clip off the errant "f/1.4" rays, it projects light more like the middle image - and the point of best overall sharpness (size of the white focused band) and contrast (brightness of the white focused band) changes. That's the focus shift.

 

The adjustment part is - if you were the Leica engineer charged with choosing which fixed setting to use for all apertures (since the focus cam is brass, not rubber), would you choose one that favored the focus point for smaller apertures, or for f/1.4, or for a compromise in between?

 

Apparently, in an age of film, Leica chose f/1.4, on the assumptions that between film's light-diffusing gelatin, and increasing depth of field/focus at smaller apertures, the shift would be barely noticeable at f/2-2.8, and most buyers were getting the lens to use @ f/1.4 if the light was low, not f/2.

 

Now add to that some variation in manufacture and assembly ("zero tolerance" is fiction in any endeavour), and one could get a lens misadjusted to the compromise location (call it "+" adjustment, so that both f/1.4 and f/2.8 focus look pretty good and the focus shift is hidden), or right on the money (with some apparent focus shift @ f/2-2.8) or slightly on the wrong side of f/1.4 (call it "-" adjustment, so that f/1.4 still looks OK, but the focus shift for f/2-2.8 now has real focus error added as well.

 

Take all that, and you can see why some folks see focus shift issues, occasionally strong, and others have no perceived problem. And it is both a question of the basic design - and how adjustment interplays with the basic design.

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Thanks Andy, this has surely been one of the most enlightening commentaries on the perceived problems surrounding this lens. In my case at least, I have never had the opportunity to use the lens on a digital M (still planning/thinking on the M9). I believe someone may have previously suggested that film could be more 'forgiving' of the focus shift, too?

 

In the circumstances I am unlikely to sacrifice the lens until I have had a good long look at how it handles for me on the M9, and whether or not my usage pattern discloses any obvious problems. Perhaps also I haven't previously been as meticulous in my observation given that so many users have clearly found issues. At least I now feel more confident that the 35 Summilux can still be *very* useful when care is taken ...

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BTW, if a lens is not optimally adjusted, it can be readjusted (Don at DAG does an excellent job) to the edge of front focusing at 1.4 (the + adjustment according to Andy's post). This, along with the increasing DOF, provide a little leeway for the focus to shift back when the lens is stopped down. Of course there may still be a problem for lenses that have severe shifts.

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BTW, if a lens is not optimally adjusted, it can be readjusted (Don at DAG does an excellent job) to the edge of front focusing at 1.4 (the + adjustment according to Andy's post). This, along with the increasing DOF, provide a little leeway for the focus to shift back when the lens is stopped down. Of course there may still be a problem for lenses that have severe shifts.

 

Mine is adjusted so that the DOF fields are split 50/50 at 2 meters with aperture f1.4. At f2.8, this then aperture shifts to the classically correct 1/3 behind the focus point and 2/3 in front. When I had it coded about 18 months ago, I requested that Leica left it like that and they did.

 

Wilson

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This forum is an excellent source of information (and opinion, God help us). It is also a prime source of superstition.

 

When skimming through this thread I find again that old chestnut about black lenses shifting focus and chrome lenses not, or at least less. The purveyors of this 'information', which is of course always unsubstantiated and anecdotical, seem to think that it is the brass and the aluminum, or even the surface finish, that bends the light. Focus shift is caused by spherical aberration which is a feature of all spherical lens surfaces, be they mounted in brass, ormolu or mahogany ... This SA can be corrected to a high degree in slow lenses, because the effect is caused by the difference between axial and peripheral rays, and thus ultimately by the radius of the lens. From 1:2.8 or so, SA starts to become troublesome, and is of course a prime headache in a Summilux-speed lens. And all this is in the glass. Got it? We have had since about 1610 to get it, but some people seem incapable of understanding what it is in the lens that bends the light. Little chromium-plated imps?

 

The effect proposed would have been possible if chromed lenses were systematically adjusted for final focus differently than black lenses, back in Solms. Anybody who wants to make that claim -- and to corroborrate it with evidence and reasoning? Why the devil would they do that?

 

The old man from the Age of Reason (v-e-e-r-y long ago)

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This forum is an excellent source of information (and opinion, God help us). It is also a prime source of superstition.

 

When skimming through this thread I find again that old chestnut about black lenses shifting focus and chrome lenses not, or at least less. The purveyors of this 'information', which is of course always unsubstantiated and anecdotical, seem to think that it is the brass and the aluminum, or even the surface finish, that bends the light. Focus shift is caused by spherical aberration which is a feature of all spherical lens surfaces, be they mounted in brass, ormolu or mahogany ... This SA can be corrected to a high degree in slow lenses, because the effect is caused by the difference between axial and peripheral rays, and thus ultimately by the radius of the lens. From 1:2.8 or so, SA starts to become troublesome, and is of course a prime headache in a Summilux-speed lens. And all this is in the glass. Got it? We have had since about 1610 to get it, but some people seem incapable of understanding what it is in the lens that bends the light. Little chromium-plated imps?

 

The effect proposed would have been possible if chromed lenses were systematically adjusted for final focus differently than black lenses, back in Solms. Anybody who wants to make that claim -- and to corroborrate it with evidence and reasoning? Why the devil would they do that?

 

The old man from the Age of Reason (v-e-e-r-y long ago)

 

Lars,

 

There is a very real reason why chrome/brass barrel lenses might be subject to less problems than the aluminium alloy ones. It is due to the machining and crystalline properties of the two metal alloys. Due to its crystalline structure, aluminium alloy tends to get hot when being machined and has an undesirable property called "spalling", which means that the swarf comes off the machined article in small chunks rather than a smooth curl. Brass which is more naturally ductile and has a higher heat conductivity plus a lower co-efficient of thermal expansion, is much easier to machine to the 1 to 2 micron tolerances necessary for a lens barrel. As Andy said, zero tolerance is an unattainable target so that lens barrels will come out in a range from close to ideal to those which just pass the inspection test. Now due to what I have said above, it would be perfectly possible for more of the brass bodies to be closer to the ideal specification than the aluminium ones. That is not to say that you cannot get a perfect black lens or a bad chrome on, it is just the probabilities. The aluminium and brass barrels are I believe, made on different machines (the machining lubrication requirements are different). Again it is possible that the brass machining tools may be a fraction more accurate. The big however is that on some lenses, it is only the outer barrel that is brass and all the internal components, which hold the elements in place are the same for both black and chrome lenses. In that case I totally agree with you, it can only be perception that makes an apparent difference, not reality.

 

Wilson

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Another plausible reason is the chrome ones were probably made in one batch that was adjusted properly, while the black ones were made throughout the production cycle in different batches, some adjusted properly some not.

 

Lars,

 

There is a very real reason why chrome/brass barrel lenses might be subject to less problems than the aluminium alloy ones. It is due to the machining and crystalline properties of the two metal alloys. Due to its crystalline structure, aluminium alloy tends to get hot when being machined and has an undesirable property called "spalling", which means that the swarf comes off the machined article in small chunks rather than a smooth curl. Brass which is more naturally ductile and has a higher heat conductivity plus a lower co-efficient of thermal expansion, is much easier to machine to the 1 to 2 micron tolerances necessary for a lens barrel. As Andy said, zero tolerance is an unattainable target so that lens barrels will come out in a range from close to ideal to those which just pass the inspection test. Now due to what I have said above, it would be perfectly possible for more of the brass bodies to be closer to the ideal specification than the aluminium ones. That is not to say that you cannot get a perfect black lens or a bad chrome on, it is just the probabilities. The aluminium and brass barrels are I believe, made on different machines (the machining lubrication requirements are different). Again it is possible that the brass machining tools may be a fraction more accurate. The big however is that on some lenses, it is only the outer barrel that is brass and all the internal components, which hold the elements in place are the same for both black and chrome lenses. In that case I totally agree with you, it can only be perception that makes an apparent difference, not reality.

 

Wilson

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Lars,

 

There is a very real reason why chrome/brass barrel lenses might be subject to less problems than the aluminium alloy ones. It is due to the machining and crystalline properties of the two metal alloys. Due to its crystalline structure, aluminium alloy tends to get hot when being machined and has an undesirable property called "spalling", which means that the swarf comes off the machined article in small chunks rather than a smooth curl. Brass which is more naturally ductile and has a higher heat conductivity plus a lower co-efficient of thermal expansion, is much easier to machine to the 1 to 2 micron tolerances necessary for a lens barrel. As Andy said, zero tolerance is an unattainable target so that lens barrels will come out in a range from close to ideal to those which just pass the inspection test. Now due to what I have said above, it would be perfectly possible for more of the brass bodies to be closer to the ideal specification than the aluminium ones. That is not to say that you cannot get a perfect black lens or a bad chrome on, it is just the probabilities. The aluminium and brass barrels are I believe, made on different machines (the machining lubrication requirements are different). Again it is possible that the brass machining tools may be a fraction more accurate. The big however is that on some lenses, it is only the outer barrel that is brass and all the internal components, which hold the elements in place are the same for both black and chrome lenses. In that case I totally agree with you, it can only be perception that makes an apparent difference, not reality.

 

Wilson

 

Another plausible reason is the chrome ones were probably made in one batch that was adjusted properly, while the black ones were made throughout the production cycle in different batches, some adjusted properly some not.

 

Be this as it may - but this is a question of tolerances, of quality standards - and many claim the chrome lenses have better quality.

 

IF there is REALLY an issue with the black LuxA 35s compared to the chromes, this issue is NOT of SA or focus shift, but another, that hasn't been discussed in full. I remember sb claiming a lens inside the blacks might not be fitted correctly or could come out of the correct position and the "aspherical" was better in this regard. But this would be another issue.

We should not mess different issues up, when there is a problem with a lens. This drives everyone crazy.

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This forum is an excellent source of information (and opinion, God help us). It is also a prime source of superstition.

 

When skimming through this thread I find again that old chestnut about black lenses shifting focus and chrome lenses not, or at least less. The purveyors of this 'information', which is of course always unsubstantiated and anecdotical, seem to think that it is the brass and the aluminum, or even the surface finish, that bends the light. Focus shift is caused by spherical aberration which is a feature of all spherical lens surfaces, be they mounted in brass, ormolu or mahogany ... This SA can be corrected to a high degree in slow lenses, because the effect is caused by the difference between axial and peripheral rays, and thus ultimately by the radius of the lens. From 1:2.8 or so, SA starts to become troublesome, and is of course a prime headache in a Summilux-speed lens. And all this is in the glass. Got it? We have had since about 1610 to get it, but some people seem incapable of understanding what it is in the lens that bends the light. Little chromium-plated imps?

 

The effect proposed would have been possible if chromed lenses were systematically adjusted for final focus differently than black lenses, back in Solms. Anybody who wants to make that claim -- and to corroborrate it with evidence and reasoning? Why the devil would they do that?

 

The old man from the Age of Reason (v-e-e-r-y long ago)

 

Lars,

it is always a pleasure to read your posts !

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