How long does it take Leica to produce a lens, in the old days

[Shu_downunder]

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1 hour ago, Erato said:

"How long does it take Leica to produce a lens, in the old days"...are you sure that the question is 100% accurate?
Or "How long does it take Leica to produce a lens after R&D, in the old days" is more preciseness and it's much close to your motivation?

You are totally correct, I agree.

[adan]

Here's a little info from the Financial Times article linked at the bottom

Leica receives molded blanks of glass from Schott in Mainz. The sentence is ambiguous, but it sounds like Schott may mold the glass to a rough approximation of the final optical shape, to avoid unnecessary grinding and glass waste (rough molding is faster than grinding). I.E. the molded blanks are not necessarily flat-sided, but pre-shaped to convex or concave or flat on one side or the other, with "room" left for fine grinding to the final exact shape.

- Grinding one surface can take from 45 minutes to 2 hours (this is mentioned in the context of the 50mm APO-Noctilux-ASPH).

(Note that aspheric elements have been molded since the 1990s, no longer ground. Much, much faster and less expensive than grinding (which produce a lot of failed elements), once Hoya and Leica worked out the technology).

- Polishing the shaped elements takes 6 minutes of pre-polishing and 6 minutes of final polishing, presumably with some set-up time in between.

- coating the lens in a vapor deposition oven (also in multiples) - time is not given. 8-9 coatings are applied (Multi-coating). Can be done en masse (several dozen pieces of glass in the coating oven at once).

- cementing elements together requires about 20 seconds exposure to UV light to set the epoxy, but getting the elements aligned before setting the cement is done by hand (using an air nozzle to "blow" delicate pressure onto the glass here and there to make tiny corrections down to 1/100mm). No time given for that.

It doesn't say, but I would assume alignment is judged by having lighting and filters that produce interference patterns (Newton Rings, Moire) between the two glass surfaces. When the rings are perfectly round and evenly spaced, the positioning and alignment is correct, and the cement can be set by the UV.

- the edges of each element or cemented group are painted black to prevent flare. Takes about 15 seconds (per a video) to do the painting (lens is spun around its center, paint brush is held steady by hand). The setup to mount the glass on the rotating pedestal could be ????? minutes. Afterwards, the paint is baked for 48 hours at 50°C (presumably many units together).

At that point, the glass is finished, and ready to be assembled into the metal lens barrel or tube.

https://www.ft.com/content/1e27b37c-21f7-11e8-8138-569c3d7ab0a7

Leica has at least two facilities for CNC-machining metal, both separated from the final assembly building to prevent contamination from metal shavings and dust. In Leica Park Wetzlar, Leica has a separate subsidiary - Uwe Weller Feinwerktechnik - on site to do metal machining. A few lens parts, some cameras parts, and also creation of "bespoke" manufacturing machines (testing devices, etc.) that Leica themselves use in their own building. Many other metal parts are machined at the Leica Portugal factory, and shipped to Wetzlar for final assembly.

Generally, the metal is machined in batches (small-scale mass production) - e.g. 200 (or 2000) focus rings for 90mm APO-Summicron lenses, all made one right after the other to save having to change the CNC programming every time.

That is why it is a bit hard to specify an exact build-time for lenses (or cameras). Some of the steps can be done en masse for several dozen pieces of glass at once. Some have to be done one at a time (but perhaps in parallel on multiple side-by-side machines). Some metal parts can be produced in small-scale mass production, and some have to be made one at a time. Some parts can be pre-assembled in Portugal, and shipped ready to install in Wetzlar (or for the time being, in Portugal). The metal parts can be produced in parallel with the glass parts - one factory working on metal at the same time another is working on glass. Or a year's supply of a part can be run off in a couple of days, and stored until needed for final assembly.

In other words, Leica does not start out with 6 rough pieces of glass, and 50 lumps of metal, and produce one lens at a time from beginning to end. Leica produces glass and metal parts in various degrees of mass-production - and then assembles lenses from those parts as a final step. (And then tests them, of course).

This 5-minute video happens to show lenses, prisms, and other parts for Sports Optics (spotting scopes and binoculars) - but the procedures and techniques for handling glass and metal are pretty much the same for Leica camera lenses.

I think the shortest answer would be - "as long as it takes."

 

[adan]

One can come at this from another direction.

In 2014, making M, TL/CL, cine, and S-mount lenses, Leica produced about 120000 lenses (at least per our wiki, which shows that many lens serial numbers were assigned.)

Leica has ~1800 employees world-wide. Eliminating administrative, sales, R&D, and camera workers, let us assume that 800 of those are involved in lens production (making lens parts, and assembling the parts into lenses, but NOT including optical and mechanical design work).

Let us assume a work week per worker of 40 hours (in Germany, that may be a high estimate, don't know about Portugal) and a 48-week work year.

So each worker works 1920 hours per year, and all the 800 workers together work 1536000 hours per year, to produce 120000 lenses.

That works out to 12.8 hours per lens.

I would suspect that in "the old days," the time, allowing for simpler lenses but also somewhat less mechanized production and more hand-adjustment in the final stage, might not have been much different.

Depends on what one considers "the old days" - the 1930s, the 1950s, Leitz Canada in the 1980s? Most of the core technology of mechanized lens grinding and polishing  and "assembly-line" mass parts production existed long before Leitz began commercial production of the Leica and its lenses in 1925.

Leonardo Da Vinci (ca. 1500) sketched (but never built) "mechanisms" for holding multiple lenses at once for polishing, or for grinding concave surfaces in optical lenses and mirrors. Samuel Colt demonstrated "interchangeable parts" in 1851 by disassembling 10 revolvers, tossing the parts into one box, and then reassembling 10 guns by picking parts out of the box at random. Henry Ford has established his automobile assembly line by 1913 (same year as the Ur-Leica prototype).

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Now let us assume the cost of a Leica worker (wages & benefits) is €60000 per year, or €31 per hour. Maybe less in Portugal, and maybe not.

That would make the average labor cost of a Leica lens €400. That of course does not include materials, supplies, machinery amortization, packaging, accessory parts (caps), etc. etc. - or the overhead of the administrative staff.

One can argue with or update my assumptions, and insert different values in those equations.

And obviously any particular lens type may require more, or less time, depending on how complicated it is (4-element 90 Macro-Elmar-M vs. 23-element 90-280 APO-Vario-Elmarit-SL-ASPH).

Edited April 18, 2021 by adan