Very interesting answer from Leica on 35mm 1.4

[castelletta]

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Mine is the same black 35mm cron, bought new from an official Leica reseller this april and already coded by Leica.

 

It too has focus shift that places the point of focus OOF between F2.8 and 8.

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[Jamie Roberts]

I have just PM's Sergio to ask him which his lens is, since his was the one that passed the test most convincingly...

 

We should probably start a list of who has what, either way so in the next post (Title "Leica 35mm Lens Survey Response" I give my answer.

 

Don't know how many people will actually see this query, folks, since it's outside the M8 subdivision now.

 

Tim--ping Guy Mancuso as well. I believe his is new, black, coded and working.

[sean_reid]

OK, I've done the tests (heavily focus bracketed to be sure that the first F/1.4 exposure, in the chosen series, shows the highest possible resolution). My tests for this (as seen in the CV 40/1.4 article) involve three bottles (with fine print labels) located at three different distances from the camera:"X", "X plus 1 inch" and "X minus one inch". No rulers, just objects with sufficient detail to show differences in focus.

 

Focus distance for this series was about 3 feet.

 

 

Here's what I'm seeing with the 35/1.4 Lux Asph:

 

F/1.4 - good resolution at chosen focus distance

F/2.0 - good resolution at chosen focus distance

F/2.8 - slight back focus but bottle at chosen focus distance still shows good resolution

F/4.0 - slight back focus but bottle at chosen focus distance still shows good resolution

F/5.6 - slight back focus but depth of field almost masks the difference

F/8.0 - slight back focus but depth of field almost masks the difference

F/11 - depth of field masks any focus shift

 

Basically, starting at F/2.8 the bottle that is 1" back from the set focus distance shows the highest resolution of the group but the middle bottle (at the set focus distance) still retains good resolution. At no aperture did the bottle at the set focus distance go completely out of focus. Rather, at F/2.8, that bottle ceded "best focus" to the one slightly further back.

 

My conclusion from this sample? Focus shift does exist with this lens and can be seen with subjects that are located close to the camera. That said, the lens still provides fairly good resolution, at the set focus distance, through F/8. Thereafter, diffraction limits things. The further the subject is from this lens, the less one will notice any effects of this slight backfocus.

 

I myself would not hesitate to use this copy of the 35/1.4 Aspherical at any aperture. The shift in this copy just isn't very significant. I recommend the bottle test to those who are interested (rather than the ruler test).

 

Some wonder if reviewers get "ringers" - special high performance examples of a given product. The reality is that press pool lenses often get abused and beaten up (although not by me). Some of them I see are in much rougher shape than a new lens would be. Such was the case with this copy of the 35/1.4 Asph - it has seen some heavy use. It's no ringer. In fact, I suspect that it was out circulating among journalists for quite awhile before Leica coded it.

 

It's still, cost aside, my favorite 35 of all time.

 

Cheers,

 

Sean

[tashley]

OK, I've done the tests (heavily focus bracketed to be sure that the first F/1.4 exposure in the chosen series, shows the highest possible resolution). My tests for this (as seen in the CV 40/1.4 article) involve three bottles (with fine print labels) located at three different distances from the camera:"X", "X plus 1 inch" and "X minus one inch". No rulers, just objects with sufficient detail to show differences in focus.

 

Focus distance for this series was about 3 feet.

 

 

Here's what I'm seeing with the 35/1.4 Lux Asph:

 

F/1.4 - good resolution at chosen focus distance

F/2.0 - good resolution at chosen focus distance

F/2.8 - slight back focus but bottle at chosen focus distance still shows good resolution

F/4.0 - slight back focus but bottle at chosen focus distance still shows good resolution

F/5.6 - slight back focus but depth of field almost masks the difference

F/8.0 - slight back focus but depth of field almost masks the difference

F/11 - depth of field masks any focus shift

 

Basically, starting at F/2.8 the bottle that is 1" back from the set focus distance shows the highest resolution of the group but the middle bottle (at the set focus distance) still retains good resolution. At no aperture did the bottle at the set focus distance go completely out of focus. Rather, at F/2.8, that bottle ceded "best focus" to the one slightly further back.

 

My conclusion from this sample? Focus shift does exist with this lens and can be seen with subjects that are located close to the camera. That said, the lens still provides fairly good resolution, at the set focus distance, through F/8. Thereafter, diffraction limits things. The further the subject is from this lens, the less one will notice any effects of this slight backfocus.

 

I myself would not hesitate to use this copy of the 35/1.4 Aspherical at any aperture. The shift in this copy just isn't very significant. I recommend the bottle test to those who are interested (rather than the ruler test).

 

Some wonder if reviewers get "ringers" - special high performance examples of a given product. The reality is that press pool lenses often get abused and beaten up (although not by me). Some of them I see are in much rougher shape than a new lens would be. Such was the case with this copy of the 35/1.4 Asph - it has seen some heavy use. It's no ringer. In fact, I suspect that it was out circulating among journalists for quite awhile before Leica coded it.

 

It's still, cost aside, my favorite 35 of all time.

 

Cheers,

 

Sean

 

So how do I get to buy that lens?!

 

May I ask what serial number range it is in, just to try to work out whether it was coded at birth or retro-coded as you suspect? If I were being cynical I would say that the current weight of evidence is that the new ones are worse and if a I wanted a reviewer to get a good sample I'd send an older one!

 

Also, though I run 'ruler tests' at about three feet on lenses if they seem to be behaving badly in the real world, it is my experience that whatever theory dictates, the problem is most significant at greater distances. I baulk from saying 'most pronounced' becuase I wouldn't know how to measure that. But if you have time Sean, stick the thing on a tripod and shoot something twenty-odd feet way where that object is centred but where there are other objects both nearer and further within the central 1/3rd of the frame. Then compare the F4 shot to the wide open shot.

 

I suggest this because the thing that got me interested in this in the first place was never a ruler or a close-range test, but stuff at middle distances being very noticeably less sharp than they were on other lenses.

 

But I do know how very busy you are!

 

All the best and thanks for posting this!

 

Tim

[sean_reid]

Hi Tim,

 

You're welcome. I probably won't have time to do the alternate test because (for reasons of loan schedules, etc.) I'm working on three different lens articles simultaneously. If time allows, I'll try. If you really want to buy this lens, e-mail me. Who knows? Serial number is 37052XX.

 

You were correct that there is some back-focus.

 

Cheers,

 

Sean

[sean_reid]

Actually, Tim, I was thinking further and I will try to do that if time allows (after all the tests I must do first with all three sets of lenses).

 

Cheers,

 

Sean

[tashley]

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Hi Tim,

 

You're welcome. I probably won't have time to do the alternate test because (for reasons of loan schedules, etc.) I'm working on three different lens articles simultaneously. If time allows, I'll try. If you really want to buy this lens, e-mail me. Who knows? Serial number is 37052XX.

 

You were correct that there is some back-focus.

 

Cheers,

 

Sean

 

Hi Sean,

 

If I'm right, that puts the lens something like 3 to 4 years old, so very definitely not current batch. I'm mildly curious as to why they wouldn't send you a much more current one but then I am not conversant with reviewing orthodoxies!

 

I might very well want to email you - frankly I would kill to get a good 35 lux, so an email and a check seem a low price to pay in comparison! Would like to hear about your 20' test first though, if you do get a chance.

 

Best

 

Tim

[ChrisC]

... that puts the lens something like 3 to 4 years old, so very definitely not current batch. I'm mildly curious as to why they wouldn't send you a much more current one.....

 

The same question raised again; are the focus issues experienced by Tim and others only with current, M8 era, lenses?

 

.........Chris

[wparsonsgisnet]

... My conclusion from this sample? Focus shift does exist with this lens and can be seen with subjects that are located close to the camera. That said, the lens still provides fairly good resolution, at the set focus distance, through F/8. Thereafter, diffraction limits things. The further the subject is from this lens, the less one will notice any effects of this slight backfocus.

 

Just for the record, since my memory is being taxed by the length of this thread, the test is to see what shift in focus occurs when aperture is changed -- but the camera is NOT refocused. Is that right?

 

Is ask because expected behavior might be to set the aperture, based on meter readings, and then focus the camera. This is my behavior, for example.

 

In your tests, Sean, if you refocus after changing aperture. is the lens in focus where the patch is aimed?

 

tnx,

[Eoin]

This thread got me thinking today and I decided to check my own 35 Lux asph, chrome version FWIW. It's not coded but hand coded and used with a B+W UV/IR Cut filter.

All shots hand held focused at 1M on the chrome edge of the door lock with just adjustment to the aperture. Raws processed in Aperture with just sharpening on the 1.4 image and lift & stamped to the other images

 

Shots taken at 1.4, 2, 2.8, 4, 5.6 & 8

 

Tim, I know it's not what your after being chrome and all that, but your more than welcome to try it for your own information. I'm in Ireland so it won't have far to travel. I'll be getting a 28 cron soon and I won't be hanging on to this 35.

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[sean_reid]

Hi Sean,

 

If I'm right, that puts the lens something like 3 to 4 years old, so very definitely not current batch. I'm mildly curious as to why they wouldn't send you a much more current one but then I am not conversant with reviewing orthodoxies!

 

I might very well want to email you - frankly I would kill to get a good 35 lux, so an email and a check seem a low price to pay in comparison! Would like to hear about your 20' test first though, if you do get a chance.

 

Best

 

Tim

 

Hi Tim,

 

The design is the same, I believe, and I think a lens stays in the press pool as long as its design is current.

 

Cheers,

 

Sean

[sean_reid]

Just for the record, since my memory is being taxed by the length of this thread, the test is to see what shift in focus occurs when aperture is changed -- but the camera is NOT refocused. Is that right?

 

Is ask because expected behavior might be to set the aperture, based on meter readings, and then focus the camera. This is my behavior, for example.

 

In your tests, Sean, if you refocus after changing aperture. is the lens in focus where the patch is aimed?

 

tnx,

 

Hi Bill,

 

I explain my methodology in the article (which is still in early stages) but the lens is focused once for each series of exposures (F/1.4 - F/11). Focus bracketing, in this case, means making a new series of exposures for each change in focus. More about this in the article.

 

Cheers,

 

Sean

[castelletta]

Sorry to reiterate the question but I think is crucial to know it.

 

Is there some brand new 35mm cron or lux asph that don't exhibit the focus shift (mainly on distant targets)?

[tashley]

 

Tim, I know it's not what your after being chrome and all that, but your more than welcome to try it for your own information. I'm in Ireland so it won't have far to travel. I'll be getting a 28 cron soon and I won't be hanging on to this 35.

 

Eoin,

 

Thank you greatly for that, the lens seems admirably sharp throughout, exactly the sort of performance I have not been able to get on anything other than a 35 Skopar! I am marginally of the opinion that these 'focus once and then change the aperture only' tests, with no focus bracket, are the right way to go, but only truly valid if on a tripod - but you images are too consistently sharp for lack of a tripod to be a factor unless there were some extremely felicitous involuntary body movements...

 

Where abouts are you in Ireland? I am sufficiently intrigued to think of travelling... and what are the first few digits of your lens's serial number?

 

best

 

Tim

[tashley]

Hi Tim,

 

The design is the same, I believe, and I think a lens stays in the press pool as long as its design is current.

 

Cheers,

 

Sean

 

 

The reason I ask is that there is an emerging theory, with some evidence, that very current lenses are more likely to be affected... there are plenty of reports of lenses one year old and older working within acceptable tolerances. AFAIK all those reported in this thread that have unacceptable focus shift are either very recent or have been recently coded with replacement mounts. I don't know enough about 'tweaks versus new versions' to know when the design is the same and when it's different but the coded mount is clearly different in at least one way!

 

Your loaner is black rather than chrome, right?

 

best

 

Tim

[sean_reid]

Yes, it's black. BTW, this is from the current draft of the 35s article, discussing the tests of this 35/1.4 Asph:

 

"Given the current controversy over focus shift with this lens, I did ten varied aperture series with focus bracketing (instead of my usual bracketing of five exposures which is generally more than adequate). A focus bracket series, for me, begins with setting the focus distance according to the indication of the rangefinder and making a picture at the lens' widest aperture. Leaving the focus ring in place, I then make additional exposures, in one-stop intervals, through F/11. I then set the focus just slightly further back and do the series. That process continues with various settings that are just ahead of and behind the distance indicated by the rangefinder. I then look at all the F/1.4 pictures and choose the F/1.4 exposure with the highest resolution of that group and use it for the sample table. I also use the subsequent exposures (at different apertures) that were made at the same focus distance as the chosen exposure.

 

This kind of focus bracketing is necessary for any resolution comparison because A) We're human and our eyesight is not perfect and Even the best rangefinder mechanism is a mechanical device with a finite amount of precision. There is also a tiny amount of play within the various mechanical pieces that link the lens to the rangefinder, etc. The M8 uses what is probably the highest quality rangefinder ever integrated into a small-format camera but one can still move a focus ring a tiny amount without disturbing the alignment of the rangefinder windows. The M8 is vastly better than the Epson R-D1 in this respect but it can't be perfect and so focus bracketing is needed for precise evaluation."

[sean_reid]

To bring us back to where we started, you quoted a message from someone at Leica, in Solms, that said:

 

"You described that the focus moves back when stopping down the aperture.

This effect occurs due to so called spherical aberration.

 

It is an image imperfection that occurs due to the increased refraction that occurs when rays strike the lens near its edge, in comparison with those that strike nearer the center.

It´s not possible to remove this aberration completely in the optical design, especially at high speed lenses . Different aberrations need different parameters to correct them.

Unfortunately it happens when you improve one aberration (e.G. distortion), that an other aberration increases. At the end it´s a compromise between all kinds of aberrations, size, weight etc.

 

The 35mm f1.4 lens is a well balanced lens regarding all competing parameters.

But unfortunately it´s not totally free of any aberrations.

It needs to be considered, that stopping down has an effect on the focus plane and probably it needs some exercises in order to get the right feeling for the lens."

 

I think that what he or she told you is quite correct and, indeed, the lens does show some focus shift but it's minor. At least that's true for the well-used example I'm testing. So is there a focus shift - yes? Is it significant? Based on the copy I tested, I would say no.

 

Cheers,

 

Sean

[sergiolov]

The reason I ask is that there is an emerging theory, with some evidence, that very current lenses are more likely to be affected... there are plenty of reports of lenses one year old and older working within acceptable tolerances. AFAIK all those reported in this thread that have unacceptable focus shift are either very recent or have been recently coded with replacement mounts. I don't know enough about 'tweaks versus new versions' to know when the design is the same and when it's different but the coded mount is clearly different in at least one way!

 

Your loaner is black rather than chrome, right?

 

best

 

Tim

 

Hi Tim,

my lens is an uncoded summicron asph 3927xxx and I tested it also at 20 feet- not to mention all the other intermediate and up to infinity distances... LOL.

And it is black.

Ciao.

Sergio

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Hallo,

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[sean_reid]

In case anyone is interested, the CV 75/2.5 and Leica 75/2.0 do not show any focus shift in my tests.

 

Cheers,

 

Sean

[JWW]

Although I was totally happy with my 35mm ASPH Summilux, curiousity go the better of me and I did some close in 3-4ft with tape/newspaper and farther 15-20 ft tests with a fence and fencepost. Even blown way up, the close in shifts were so minor on newsprint I could hardly tell. On the far test, with the increased DOF, couldn't see any shift at all. Lens is chrome, bought new a few yrs ago, SN 3921xxx unencoded. That's all settled in my mind (at least for my lens). I just ordered a 35mm Summicron ASPH black new so when I get that I'm curious to test that one also.

 

Jan