"When did pre-war Zeiss start applying coatings?" and other questions about Tessars

I'm looking to get a 24cm Zeiss Jena Tessar for my 4x5 camera, in order to secure a more portrait-appropriate focal length relative to my current 135mm mainstay. I'm pretty broke, so I have to be careful in the choices I make. I can see a lot of these lenses in varying condition the eBay, and I'm not sure what to pick, as I assume not all production series were the same. I intend on front-mounting the lens on a Copal 3s shutter, which should fit. What I need the most help with is in finding out when they started applying coatings to their lenses, as it is very important that the one I purchase lacks any coating. Most of the answers I've found in a desultory search both here and on the wider web claim it happened within a broad period in the 30's. Is there a specific series number after which I can be sure they have coatings? Additionally, will copies this old always lack front threading on the barrel? Can I assume that all 24cm 1:9 Zeiss Jena Tessars are meant to be used with a large format camera, and will accommodate movements?

This may not answer your question, but I found these two docs helpful in understanding the history of the Jena Tessar lenses.

https://www.arnecroell.com/zeissoberkochen.pdf

https://www.arnecroell.com/czj.pdf

Hope they help.

Not for confusion, but some of uncoated lenses were also retro-coated at factories as service.
So the serial number won’t help for this case….
You can also ask Jason Lane to coat uncoated lenses if you wish….

Zeiss Tessar dates back to the early 1900's. The Zeiss Jena f9 APO Tessar versions were originally designed for process cameras to make color separation films. Larger full aperture Zeiss and other Tessars were intended "normal" photography.

Why limit the lens choice to only Zeiss as the Tessar formula were made by LOTs of other lens manufactures. Non coated lenses would be from the pre WW-II era, coatings happened en-mass soon after WW-II.

Know uncoated lenses were aftermarket coated by lens sellers like Burke & James_Lens Bank and others including Goerz which offered a coating service for their older non-coated lenses back in those days.

Motivation for using non coated lenses would be lower contrast combined with residual lens aberrations do result in a specific lens personality combined with lighting that can be highly desirable for the intended image goal. This becomes a question of the specific "look" to meet your image goals. Only way to know precisely what works best for your image needs is to test and try. The idea-belief Zeiss Tessar will fit best without testing, evaluation is very iffy at best, as it might be very possible a non Zeiss Tessar would fit your image making needs far better than the Zeiss Tessar.

Fitting a barrel lens to a copal# 3 by lens cell adapters or front mounting will unlikely be a direct thread on, a specific threaded adapter will be needed. This is often a special item which adds significant cost to the lens set up.


Bernice

According to Croell - "The Zeiss invention of lens coating shortly before WWII (initially marked by a red “T” on the mount of Jena-made lenses"...

from the first article Bill linked above...

Idea of lens coatings goes back to:

"The first, and simplest, type of AR coating was discovered in 1886 by British Physicist and Nobel Prize Winner (physics, 1904) John William Strutt, 3rd Baron Rayleigh (Lord Rayleigh). Upon testing some old, tarnished glass pieces (chemical reactions between the environment and the optical glass of his time tended to cause surface tarnishing on glass as it aged), Lord Raleigh found that – to his surprise – these tarnished pieces transmitted more light than clean, new pieces."

In 1904, a chemical method of producing AR coatings was developed by British inventor/optical designer Harold Dennis Taylor (Cooke Company), followed by the invention and development of:

~Interference-based coatings (AR coatings that remained a secret of the German military until WWII’s early stages) by Ukrainian physicist Olexander Smakula while working for Carl Zeiss Optics in 1935.

~Organic AR coatings (Langmuir-Blodgett films) by American physicists/chemists Irving Langmuir and Katharine Burr Blodgett during the late 1930s.

https://diamondcoatings.co.uk/brief-...tive-coatings/


Zeiss is not the only innovator in the world of optics.. What made Zeiss famous was more complex than just "innovation", it was more about the way Zeiss the company functioned.


Bernice

Quote:

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Originally Posted by Embdude

According to Croell - "The Zeiss invention of lens coating shortly before WWII (initially marked by a red “T” on the mount of Jena-made lenses"...

from the first article Bill linked above...

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Copied from: About the reduction of reflections of camera lenses. How T*-coating made glass invisible. by Dr. Vladan Blahnik and Dr. Benjamin Voelker
March 2016 Zeiss

The positive neologism of “transparency optics” or “T-optics” for short or “Tcoating” for reflection-reducing coatings by ZEISS may have to be attributed to the roots of the inventor Alexander Smakula (1900-1983), who was born and raised in the Ukraine. In the 1930s, Smakula was head of the Optical Surface Laboratory II of the R&D department at ZEISS in Jena, and he developed, with suggestions from A. König and H. Bauer, a process for the application of abrasion resistant, durable coatings on lenses to reduce reflections. ZEISS was the first company to produce such coatings and place them on the market. After the patent issuance to Smakula on November 1st of 1935, several years had to pass, mainly needed to introduce and improve the production process, until coated lenses were eventually brought to market. One major difficulty for the coating process is that any impurities, grease and moist residues on the glass, which could disturb the coating adhesion, have to be thoroughly removed prior to evaporation. Glass surfaces are always covered with a fine adsorbed water film from the atmospheric humidity. This very thin water film has considerable influence on the coating quality and must therefore be removed by glowing in the vacuum plant directly before coating is started. Such controlled production of thin coatings was possible thanks to the progress made in high-vacuum technology in the 1930s, which in turn was stimulated by the rapid development of thin films. In 1938, 17 coating plants were already in operation -however, because of a government directive, for military-related optical devices only. In 1940, the first coated camera lenses of the types Biotar and Sonnar were presented at the Leipzig Spring Fair. In 1941, nearly 300 lenses of the Sonnar 1,5/50mm type for the CONTAX camera were coated per month. Generally, at the beginning of the 1940s, more than 100 vacuum deposition plants were developed and optimized in conjunction with W. C. Heraeus (Onstmettingen). By 1950, all ZEISS lenses were coated and marked with a letter T in red print. At the same time, starting around 1943, tests were made for double and triple layer coatings. Such multi-layer coatings were first used in the 1950s for wide-angle lenses that often consisted of 18 or more optical surfaces. These multi-layer coatings were labelled “MC” in Jena and “T*” in Oberkochen. As of 1972, each ZEISS camera lens has been provided with a multi-layer coating (Dr. Hans Sauer, ZEISS Press Information of February 20, 1973). Further historical accounts dealing
with the T-coating can be found in publications by R. Richter (1940), K. Leistner (1941), A. Smakula (1942), J. Flügge (1960) and B. Gänswein (1997).

My suggestion is to find a Wollensak Velostigmat over 8 inch FL. I believe these are tessar formula and make lovely portraits (I use a 300mm om 5x7.) As a bonus they often come in Betax shutter. They were common in the 1920s and 30s.


Kent in SD

Very informative Bernice. Thanks to all for the warnings about manufacturers coating old lenses as a service.

I need for the lens to be uncoated so as to increase the amount of UV light passing through. I chose Tessars specifically because they appear to be the best compromise between general acuity of the image while possessing very few elements and less total glass from front-to-back than many other common designs. I've also read that even the oldest copies tend to produce relatively sharp images, which is in my interest, as I intend to shoot portraits in the UV.

Quote:

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Originally Posted by Two23

My suggestion is to find a Wollensak Velostigmat over 8 inch FL. I believe these are tessar formula and make lovely portraits (I use a 300mm om 5x7.) As a bonus they often come in Betax shutter. They were common in the 1920s and 30s.


Kent in SD

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Just to elaborate, Wollensak Velostigmat Series II (f/4.5) and Series IV (f/6.3) were Tessar designs.