Summilux 80mm F1.4?

[luigi bertolotti]

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Make the infinity test lct !!!  01af observation is far from trivial… there is still hope that my  disillusioned  statement about Leica isn't real…

 

btw…  my Tele Elmar 135 ("60") and ApoTelyt 135 ("57" and 32 years younger) , at infinity do perform AS EXPECTED FROM NUMBERS in terms of FOV

Edited July 10, 2018 by luigi bertolotti

[adan]

Correct - any lens with a floating element (or internal focusing, or any other feature that changes the optical spacing/formula in use) may well have a different effective focal length at minimum focus.

 

However, additionally - the min. focus of the 75mm f/1.4 is not 0.7 meters, but 0.75m. It simply doesn't get quite as close (nor does the Summarit f/2.4, which only focuses to the "0" of the 0.7m marking, whereas the f/2 focuses 3+mm past the marking.

 

As to why the little "exact focal length ±" numbers are engraved separately. That number itself is primarily there for the information of factory technicians, in case the lens needs servicing and/or calibrating. Thus small and as a somewhat obscure code (sometimes repeated as an ink or pencil marking inside the lens barrel somewhere, at least in older lenses).

 

In addition, there is leeway in labelling a lens as a product. Something like 5%, when it comes to focal length. Thus, almost no Leica 50mm lenses are really "50mm;" most are 52mm± - but "50mm" is a nice round number to engrave on the front and print on the box, and within the leeway.

 

Can you imagine the consternation and confusion if the primary engravings and box labels for 50 Summicrons were variously "LEICA 1:2/51.7," "LEICA 1:2/52.2," "LEICA 1:2/51.9" - "My box is marked '51.7mm,' but the engraving on the front says it is a 52.2mm! Is the 51.7mm better than the 52.2??!!" Or - "I though I bought a 50mm Summicron; it says so on the box. But the lens is engraved "LEICA 1:2/51.9mm"?! What gives?" Or "Is a 1:2/52.2 lens faster than a 1:2/50 lens? The aperture must be physically bigger!"

 

Actually, it is worse than that. Leica knows that any given combination of lens elements, each with its own tolerance variations, all added together, may produce a lens of actual focal length of 74.878 mm. Or 51.1212mm. For all practical purposes, though, those can be grouped into close approximations of 74.7, 75, 75.3 or 75.6mm, or 50.0, 51.0, 51.1, 51.3, 51.5, 51.7, 51.9, or 52.2mm. So Leica engraves sets of focus rings - in bulk - for those 4 or 7 eventualities, and simply pulls from a parts box the "closest value" to mount on a given lens, after it is tested and measured.

Edited July 10, 2018 by adan

[luigi bertolotti]

Can you imagine the consternation and confusion if the primary engravings and box labels for 50 Summicrons were variously "LEICA 1:2/51.7," "LEICA 1:2/52.2," "LEICA 1:2/51.9" ….

Adan, I liked your explanation, but think that Andy referred not to the primary (i.e. FRONT/BOX) engraving, but to the "little numbers" ….  am I right, Andy ?

[Guest]

So, from my original question I can suppose the following

 

• My original understanding that the small numbers were to be added to the focal length was wrong.
• The correct way to apply them is to "replace" the 75 with the new number in 10ths, so a 75mm with 50 = 75.0mm, a 75mm with 56 = 75.6mm.
• The first version 1 lenses were incorrectly labelled with 00, Canada thinking this meant no change, thus 75.0mm. In fact would mean 70.0mm by the German method as above, which was wrong.
• This was corrected late in the version 1 batch (some have mentioned they have versions 1 lenses with 50 stamped on them).
• Version 2, Canada and Version 3 Germany were correctly stamped.
• Version 1 lenses with 00 stamped on them could become even more collectable, like a postage stamp with printing imperfections!

The intriguing thing here is the lens designer, Dr. Mandler, worked in the Midland factory so it seems crazy that he would made this mistake with the small number stamping, but even geniuses make mistakes!

 

Thanks to all for your comments, I'm always amazed at the knowledge of you guys!

[wizard]

... Both my 75/1.4 and 75/2 have a "50" engraving but the 75/1.4 is significantly wider.

 

That's because its aperture is wider    .

[lct]

That's because its aperture is wider    .

 

 At the same aperture of course.

[luigi bertolotti]

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….

The intriguing thing here is the lens designer, Dr. Mandler, worked in the Midland factory so it seems crazy that he would made this mistake with the small number stamping, but even geniuses make mistakes…

 

Dr. Mandler was a DESIGNER… as all the great designers, he took few or no care of what happened at manufacturing level…

Edited July 11, 2018 by luigi bertolotti

[adan]

Dr. Mandler was a DESIGNER… as all the great designers, he took few or no care of what happened at manufacturing level…

 

Not entirely true, since a lens design does have to take into consideration whether, and how, it can be manufactured at an economically sensible cost (something woefully disregarded or miscalculated by the designers of the 35mm f/1.4 Aspherical and the 35-70 f/2.8 Elmarit-R). And as a manager as well as designer (a vice-president of Leitz Canada, not just an employee), Mandler was not simply a designer in an ivory tower. He walked the factory floor, received and considered production and QC reports, and consulted with the other "Walters" who ran ELCAN in his time, on the overall operation of the factory.

 

But I agree he was probably not directly involved in such minutiae as the choice of numbers to engrave on a lens.

 

And again I reiterate - these numbers were intended for internal industrial use, not for the consumer, nor for collectors enticed by "examining the entrails". So long as any Leica serviceperson understood that either 00 or 50 on a 75m lens = "75.00mm focal length," all was well.

Edited July 11, 2018 by adan

[wizard]

 At the same aperture of course.

 

I was just kidding, lct  .