What's the true story surrounding the birth of Red Scale Elmars?

[luigi bertolotti]

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Well... thinking of the long story of your old unnumbered Elmar which at the end went into a RS-f16 Mount... I wonder if the Leitz technicians did "tune" also the diaphragm mech so that the effective top closure is really f16 instead of f18... .. strictly speaking, if mounted "as is" it ought to go a bit beyond the f16 index of the new mount... (but.. is hair' splitting )

Edited September 17, 2017 by luigi bertolotti

[romanus53]

finally, I took the opportunity to take the one with diamond (1929) with me on a sunday walk, this one shot wide open:

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another one stopped down to 5.6:

both shot on M240, converted in C1, little push on the exposure-slide

[willeica]

I have a couple of Leicas which got a factory upgrade like Leitz offered to their customers. And I think the upgrade included some service on the lenses too. The remounted Elmar with red scale and diamond belongs to a I A body converted to an II synch, body no 19687. The other remounted Elmar belongs to a I C converted to Standard body nr 24115. Both lenses stayed uncoated and do not show any serial number outside. They belong to the mentioned bodies which can be dated to 1929 resp 1930. Especially the I C looks totaly different today after first converted to changeable lenses about 1935 and later got a chrom body with small plate instead of long-time expousure dial. You can see them in the background here https://www.l-camera-forum.com/topic/95318-kaviar/page-84

 

Thanks for this information. Going by the SNs you quote, your lenses started out in life mounted on I Model As. My I Model A converted to Standard is SN 23862. This is the one with the very short Elmar. I have discovered, looking into my collection drawer, that I have another very short early 7 O'Clock Elmar with no SN. It is in very good condition (close to mint), but I believe that it too started out in life on a I Model A. The barrel length of my examples is about 29mm, whereas the typical barrel length for interchangeable Elmars in the early 1930s was between 31 and 32mm. Leica did not manufacture to precise sizes in those days and there is quite a degree of variation in barrel lengths and also in actual focal lengths as indicated by the numeric codes behind the infinity lock button. The short length of the barrels on your lenses has nothing to do with the type of mount they are in now, but rather to their origins on I Model As and also to whatever 'upgrades' they received in the early 1930s.

 

William

Edited September 17, 2017 by willeica

[romanus53]

Just want to Note that there are No Numbers indicating the actual focal length on These converted and one can Close the aperture Behinderung the 16 but one can so this in the older scales besonders 18 top.

[jerzy]

Just want to Note that there are No Numbers indicating the actual focal length on These converted and one can Close the aperture Behinderung the 16 but one can so this in the older scales besonders 18 top.

Besides the one digit indicating the real focal length (stamped under the infinity knob) focal length is scratched inside, on the brass barell. You need to dismantle the lens to see it.

Interesting question of Luigi about aperture 16, 18, 22, never thought about that it. The inside barell has a cutout which is delimiting rotation of the aperture ring, I believe that the cutout is different. When back home next week I will check it.

[willeica]

Just want to Note that there are No Numbers indicating the actual focal length on These converted and one can Close the aperture Behinderung the 16 but one can so this in the older scales besonders 18 top.

 

Leica would usually have put this on the back of the mount underneath where the infinity knob clicks in. It is usually a single digit which can then be used to consult a table which gives the real focal length. That was certainly the case for many years. Do you know who remounted your lenses?

 

William

[luigi bertolotti]

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Did the actual focal length stay the same over the time?

Jan

As above said, real FL is related to the small engraving under the knob (I don't have the corresponding tab of values... does anyone has it to share ?) ; the nominal FL I think was Always 50mm/5cm (I mean, the "factory FL".. obviously the "commercial" has Always been the engraved...)

 

When this year I bought a "5 digits / 50mm" Elmar, I noticed it had "5", whilst my RS (> 1.xxx.xxx) has "7" : for curiosity, I made a decently precise test to measure horizontal FOV (tripod, camera vertical, ruler, both at infinity with the same OUFRO extender and same BM adapter)

Here are the results with the two limits of the horizontal FOV at around half of the frame :

 

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The operation of changing the lens caused a slight shift... (my fault... ...vertical position remained rigorously the same) but anyway,I'd say, it's a difference well under 0,5 mm on 19,5 mm ca. of horiz. FOV

Edited September 17, 2017 by luigi bertolotti

[romanus53]

The Elmar from 1929 bears a 3,the other one a 1. Both were remounted by Leitz when the cameras got an Upgrade.

[jc_braconi]

I have read an article in an old VIDOM about all the markings on the Elmar 3.5/50
dont have close to me the magazine actually.
A lot of things to check during the next winter.

[willeica]

The Elmar from 1929 bears a 3,the other one a 1. Both were remounted by Leitz when the cameras got an Upgrade.

 

3 is 48.6mm and 1 is 49.6mm according to a table which I have:

 

The full table is below:

 

0 - 50.5mm

1- 49.6mm

3 - 48.6mm

4 - 50.7mm

5 - 51mm

6 - 51.3mm

7 - 51.6mm

8 - 51.9mm

 

I imagine the word 'nearest to' could be added here. Leica was, in my view, on a journey from a craft business to a mass manufacturer of camera lenses. The company hardly decided that on this day/week/month we will manufacture Elmars at, say, a focal length of 51mm. If JC or anyone has information from VIDOM or elsewhere about these markings it would be good to know how and why this happened and how Leica came up with the number system.

 

William

[wlaidlaw]

My unserialised black scale Elmar has f18 as its smallest aperture. I assume it comes from 1931, as that is the date of the 1C standard it comes with. It is a standard (O) marked lens. 

 

Wilson

[luigi bertolotti]

3 is 48.6mm and 1 is 49.6mm according to a table which I have:

 

The full table is below:

 

0 - 50.5mm

1- 49.6mm

3 - 48.6mm

4 - 50.7mm

5 - 51mm

6 - 51.3mm

7 - 51.6mm

8 - 51.9mm

 

... 

William

Thanks William... interesting... strangerly, from my test above depicted, I had said that the Elmar with "7" had a focal a bit SHORTER than the Elmar marked "5"... but the two items are from 1930 and 1955.. who knows if the values had rmained the same over that period, with war in the middle...

Edited September 18, 2017 by luigi bertolotti

[UliWer]

3 is 48.6mm and 1 is 49.6mm according to a table which I have:

 

The full table is below:

 

0 - 50.5mm

1- 49.6mm

3 - 48.6mm

4 - 50.7mm

5 - 51mm

6 - 51.3mm

7 - 51.6mm

8 - 51.9mm

 

I imagine the word 'nearest to' could be added here. Leica was, in my view, on a journey from a craft business to a mass manufacturer of camera lenses. The company hardly decided that on this day/week/month we will manufacture Elmars at, say, a focal length of 51mm. If JC or anyone has information from VIDOM or elsewhere about these markings it would be good to know how and why this happened and how Leica came up with the number system.

 

William

 

Do you have a source for this table?

 

In the list which was found by telewatt and first published in the thread linked above in #18 the description for the different numbers apply to the pitch of the focussing thread.

 

You find the text on p.10 under "Focusing Mount, designation of pitch":

 

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[willeica]

I'm travelling and will try to find my source when I get back on Wednesday. I took these from a created document but I got them from a source which I don't have with me.

 

William

[luigi bertolotti]

Sorry, Uliwer, which is the thread where Telewatt did linked that old factory doc ?  Seems to me isn't this one... is from the german Forum ?  I ask because  is very intriguing for me... an old syle structured Bill-Of-Material on paper (today, BOMs are hot topics in any ERP and/or PLM  Software... in my day by day job, an item we deal with ad nauseam...  )

 

EDIT : ok, found it from your quoting of post 18... 

 

(btw... not a BOM at 1st level but a spare parts list... much simpler infos to manage, indeed.. . even if usually some factory codes can be shared  )

Edited September 18, 2017 by luigi bertolotti

[luigi bertolotti]

Do you have a source for this table?

 

In the list which was found by telewatt and first published in the thread linked above in #18 the description for the different numbers apply to the pitch of the focussing thread.

 

Thinking well... there is anyway a strict relationship... a different Focal Length does require a different pitch if you want to keep the same rotation (in degrees) to focus from, say, 1 meter to infinity.

So it makes sense that there is a correspondance table - official factory document - that relates those number to the real FL of the Elmars.

 

Curios that the above doc quotes 0,1,3,6,7,8 and refers to lenses up to 650.700 ...  as above said my Elmar 5 digits (well under 650.700...   ) has 5 and my RS Elmar (well above 650.700) has 7...  but the era of 5 digits was really the dawn of industrial organization of Leica items manufacture... many changes in time by sure... 

Edited September 18, 2017 by luigi bertolotti

[willeica]

Does anyone, particularly German speakers, have this publication?

 

Ulf Richter, Die Entwicklung der 5cm Objektive zur Leica 25 Jahre Leica Historica, Erstauflage Juli 2000

 

It may contain some details on the focal length issue.

 

The following from Puts (Leica Chronicles) is also interesting but not conclusive on the precise numbering system:

 

The choice of the focal length of 50 mm for the Leica has a logical explanation. The usual definition of a standard lens is one that has a focal length equal to the diagonal of the negative area. For the Leica format that would be a focal length of 45 mm. Industry standards in that period introduced a tolerance of 6% for the stated focal length: a nominal/engraved focal length of 50 mm could be effectively varying between 47 mm and 53 mm. Berek opted for an effective focal length of 51.9 mm, which gave an angle of view of 45 degrees, less than what would be the standard 53 degrees. Berek knew that the Elmar was a bit weak in the corners and this would show when the negatives were enlarged. Therefore he restricted the angle of view to cut off the weak outer zone.

 

 

William

[Juan Valdenebro]

A new question about the birth of the red scale elmars:

Max Berek was the original 1920's Elmar's designer, but he died in 1949, while the Elmar's optical formula was recomputed for the red elmars in 1951... Was there a specific lens designer in charge of that project?

I think Midland and Mandler's most known lenses came just some time after that, beginning in the early 50's...

Was Mandler, before his Midland work, related to that recomputed formula?

Were early computers used for that lens' new formula?

Is there any site with information on that new formula development?

Thanks.

[luigi bertolotti]

A new question about the birth of the red scale elmars...

...

Were early computers used for that lens' new formula?...

I have been in the EDP world for so longtime that i feel rather confident to answer to the above question : and the answer is NO, if we mean "early computers" as "programmable digital electronic calculators" : in the era we are speaking of, such machines, de facto, didn't exist yet or at least weren't commercially available (the first one can be defined the IBM 704 - 1954).

 

In those years, the best way to perform the long and iterative computations for lens design, mostly centered on trigonometric/logaritmic functions , was probably to use electro/mechanical scientific calculators, that were not programmable but fast, reliable, and at a price that allowed a Company like Leitz to buy 10/12 or so for the optical computing department people (they were "desktop devices" and several Germany / made existed at those times: Triumph, Walther, Diehl... and italian Olivetti, too)

 

... and of course any skilled engineer had HIS trustable slide ruler.. ... many people were really FAST to use it : the problem was that you can't count, typically, on more than 3 significant digits , with a slide ruler... so is good for "first level" engineering evaluations.. when you have decided the final direction and need (as happens for precision optics/mechanics) 4 or 5 or 6 significant digits, the electro-mechanical calculators were unavoidable.

Edited September 21, 2017 by luigi bertolotti

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Hallo,

Look here: Interesting Leica gear

[romanus53]

After Berek passed away Helmut Marx was head of "Rechenbüro" but the Zuse came later. https://www.l-camera-forum.com/topic/32019-zuse-z5-bei-leitz-weitzlar-und-erste-computertechnik/ and  https://www.l-camera-forum.com/leica-wiki.en/index.php/Helmut_Marx The redesign of the Elmar may be computed with elector-mechanical machines like http://www.rechnerlexikon.de/artikel/Mercedes