Kodak began experimenting with lens coatings on a production basis in the later 1930s. In his 1951 book, Lenses in Photography, Rudolf Kingslake, then Director of Optical Design for Kodak, reports that calcium fluoride, as an optical coating, was first offered for commercial use in 1938, but its softness relegated it to inner surfaces. As other fluorides were developed for lens coatings and the vacumn deposition techniques to apply them were refined, the coated surfaces became as hard as the glass they covered.  
 
This illustration from the Kodak Data Book, Kodak Lenses, Shutters and Portra Lenses, shows a schematic of the way lens coatings work to cancel reflections. In the left frame, the lower half of the lens is coated, so that reflections D and E are out of phase and cancel each other. The photograph at the right is of a lens with one side coated and the other uncoated when a bright light source is shown on the lens.
 
 

Kingslake's accounts are probably as authoritative as any we are likely to see published and those are circumspect in the chronology of developments through the early 1940s of Kodak's coating procedures. Product brochures and reference publications establish that softcoating was added to the premium models of lenses about 1941-- the 14-inch Eastman Ektar for large format cameras, the Ektars for the Ektra, the 100mm Ektar for the original Medalist and the companion 105mm f /3.5 Heliar for small press cameras. Kodak's printed materials for these products mention either lens coating for inner surfaces or a process that reduces reflections. There is no general discussion of lens coating in the lens section of the Kodak Reference Handbook, 1940 or 1942-45 editions. The Data Book: Kodak Lenses Shutters and Rangefinders:For Revising Kodak Reference Handbook, © 1942, 1945, Second 1946 Printing contains the first discussion of the Lumenizing process and the branding mark in these publications. The July 1946 number of Kodak Handbook-Notebook News list a 4-page article, KODAK LUMENIZED LENSES, ANTI-REFLECTION COATING.

Kodak may have been discrete in describing its early lens coating technologies because it was experimenting with hard coating from roughly 1940 through 1945. Kodak produced cameras, lenses, sighting devices and rangefinders for the U. S. Army and Navy during WWII and perhaps tried different coatings for different applications. It is possible that not all of the Kodak production lines were updated with the capability of using coated lens elements at the same time. While war-time advertisting was clearly anticipating the postwar consumer market -- for example, in this Medalist ad -- fixing the end date of the war would have been guesswork and revealing information about things like the coatings on Aero Ektars was likely prohibited.

Based on Richard Knoppow's pre-2000 inquiry with Kodak , Kodak records of when they started applying coatings to their lenses were no longer accessible. The collection of Kodak papers at the University of Rochester might hold some information about lens coating practices during this period. Michael Briggs has examined a reasonably large sample of military Aero Ektars, some as early as 1941, and found that all but one were coated, though not marked with the characteristic .

While the table below is anything but a comprehensive registry of Kodak lenses, I have asked for and many visitors have responded with information about Kodak lenses of this period. That has been helpful in trying to fill in the gaps about early 1940s coatings. As of August 2010, there doesn't seem to be a reason to update this table with data for hardcoated lenses marked from 1946 onwards, nor for uncoated lenses manufactured before 1945. The following lenses are of still of interest in establishing Kodak lens coating practices:

  • Lenses marked with before 1946
  • Coated unmarked lenses before 1946
  • Ektra Ektars of any age that appear to be hardcoated
  • Kodak lenses with the pre-CAMEROSITY numbering scheme that appear to be coated.
  • Kodak professional lenses made after 1965, to define Kodak's last contribution to this market

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While later lenses will have an obvious color tint in the glass, determining whether coating is present is sometimes difficult with early lenses, often because these lenses have fewer optical surfaces on which the coating is applied. Those involved in Kodak's early coating process would have known how to differentiate the appearance of uncoated, calcium fluroide-coated and magnesium fluroide-coated glass; the rest of us have to rely on inference. EY Ektra Ektars almost certainly would have had calcium fluroide-coated glass. They are pretty indistinguishable from ER Ektra Ektars, which may have been hardcoated, and more obviously coated than more modest mid-40s lenses that are Lumenized. Uncoated lenses will have no colored refections off different optical surfaces when a light sources is reflected at an oblique angle, whereas the light source reflected off different surfaces of a coated lens will appear in slightly different colors. Different light sources can affect appearance.

Kodak Ektars from 1946 through 1965 were single-coated; and it is possible that some Ektars after 1965 were multi-coated, though Kodak's offerings in the prosumer market by this point were a trickle. Kodak AG lens production followed Kodak's U. S. conventions; coated lenses were marked with ; it is possible, but not very likely that late model Retinas may have been multi-coated. Generally, the additional coating layers in multi-coated lenses are designed to filter out reflections at wave lengths not filtered by a single coating. About 1970, lens makers began the strategic application of six or seven coatings that filter most frequencies of visible light. The greater the number of air/glass surfaces, the greater the need for effective coating. Multicoating of modern lenses with many elements, particularly zoom lenses, is essential to maintain good contrast. For the kinds of formulas used for most Ektars, multicoating would make only a marginal contribution to flare reduction and then primarily in color.

Kodak research showed that lens baffle design was as important as lens coating in reducing lens reflections that decreased contrast, so cameras designed in the late 1930s and throughout the 1940-50s had improved baffles and paint materials.

Additional information about the history of lens coating
and a large collection of posts about lens coatings.


   
  Kodak assigned serial numbers to Anastigmat Special/Anastar and Ektar lens. Prior to about 1940 it used a single numeric sequence, 54321, while serial numbers after that were alpha-numeric, two letters and three or four numbers -- ES3682. The letters in the U. S. were mapped to the word (sic) "CAMEROSITY", while in England, the mapping was to "CUMBERLAND".    
 
EY = 1940
EC = 1941
EA = 1942
EM = 1943
EE = 1944
ER = 1945
EO = 1946
ES = 1947
EI = 1948
ET = 1949
RY = 1950
RC = 1951
RA = 1952
RM = 1953
RE = 1954
RR = 1955
RO = 1956
RS = 1957
RI = 1958
RT = 1959
OY = 1960
OC = 1961
OA = 1962
OM = 1963
OE = 1964
OR = 1965
OO = 1966
OS = 1967
OI = 1968
OT = 1969
   

DATA ON SELECTED KODAK LENSES
1935-1965

Lenses are ordered by Kodak brand, then by length. All shutters for Anastigmat Special/Anastar and Ektar lenses are mounted in Kodak Supermatic or Flash Supermatic shutters unless otherwise marked according to the legend in the footnotes.


LENS SERIAL NUM NOTE LENS SERIAL NUM NOTE
ANASTIGMAT SPECIALS/ANASTARS *          Ektar 90mm f/3.5
(Ektra) EFP
EY277 ('40) Soft coated;
           
Anastig Spec 47mm f/4.5 (Bantam) KOD EY6752 ('40) Not coated Ektar 100mm f/3.5
(Medalist I)
EM128 ('43) Soft coated
Anastig Spec 47mm f/4.5 (Bantam) KOD ER7303 ('45) Perhaps coated
 
Ektar 100mm f/3.5
(Medalist II)
ES5885 ('47) Coated
Anastig Spec 48mm f/4.5 (Flash Bantam) KOD ES7697 ('47) Coated
 
Ektar 100mm f/3.5
(Medalist II)
ET205 ('49) Coated
Anastig Spec 48mm f/4.5 (Flash Bantam) KOD EI120164('48) Coated

     
Anastar 50mm f/3.5
(Kodak 35 RF)
KOD
EI6259 ('48) Coated

     
Anastar 80mm f/3.5
(Kodak Reflex II)
KOD
--- Coated

     
Anastig Spec 101mm f/4.5 (Monitor) EY2638 ('40) Not coated Ektar 100mm f/3.5
(Medalist II)
ET582 ('49) Coated
Anastig Spec 101mm f/4.5 (Monitor) EO3652 ('46) Probably coated
 
WF Ektar 100mm f/6.3 EI346 ('48) Coated
 
  Anastig Spec 101mm f/4.5
(Senior)
EO9578 ('46)

Coated

Ektar 101mm f/4.5 E03946 ('46) Uncoated
  Anastig Spec 101mm f/4.5 (Monitor) EO11398('46) Coated
 
Ektar 101mm f/4.5 ES3682 ('47) Coated
Anastig Spec 101mm f/4.5 (Monitor) EO14297 ('46) Coated
 
     
      Ektar 101mm f/4.5 ES14029 ('47) Coated

Anastig Spec 127mm f/4.5 (Senior) EC1511 ('41) Not coated Ektar 101mm f/4.5 EI205 ('48) Coated
Anastig Spec 127mm f/4.5 (Monitor) EC1685 ('41) Probably coated
 
Ektar 101mm f/4.5 EI314 ('48) Coated
      Ektar 107mm f/3.7 No. 562 May be soft coated
      Ektar 127mm f/4.7 EE3160 ('44) Not coated
      Ektar 127mm f/4.7 EE4647 ('44) Not coated
      Ektar 127mm f/4.7 EE1384 ('44) Coated
      Ektar 127mm f/4.7 ER6584 ('45) Not coated
      Ektar 127mm f/4.7 ER7138 ('45) Not coated
           
             
  Anastar 101mm f/4.5 (Tourist II) KSR RA2237 ('52) Coated
Ektar 127mm f/4.7 ES2525 ('47) Coated
. . . Ektar 127mm f/4.7 ES7918 ('47) Coated
      Ektar 127mm f/4.7 EI7637 ('48) Coated
           
      Ektar 127mm f/4.7 SC RC5900 ('51) Coated
      Ektar 127mm f/4.7 SC RM1333('53) Coated
ANASTIGMAT EKTARS, EKTARS, COMMERCIAL EKTARS, WIDE FIELD EKTARS Ektar 127mm f/4.7 SC RI284 ('58) Coated
Anastig Ektar 45mm f/2.0 (Bantam Spec) CR 15700 Not coated Ektar 127mm f/4.7 RI2875 ('58) Coated
. . . Ektar 135mm f/3.8
(Ektra) EFP
ER255 ('45) Soft coated; maybe hard coated;
. . . Ektar 152mm f/4.5 EO961 ('46) Coated
Ektar 44mm f/3.5
(Signet)
KOD
RC54598 ('51) Coated
Ektar 152mm f/4.5 ES963 ('47) Coated
Ektar 44mm f/3.5 (Signet) KOD RE17883 ('54) Coated
. . .
Ektar 44mm f/3.5 (Signet) KOD RR1959 ('55) Coated
Ektar 7 1/2 f/4.5 ACME EI 687 ('48) Coated
      Ektar 7 1/2 f/4.5 ACME

0 - EI 1630
('48)

Coated

Ektar 50mm f/1.9 (Ektra) EFP

EY1254 ('40) Soft coated      
      Ektar 7 1/2 f/4.5 ACME OR120 (''65) Coated
      WF Ektar 190 f/6.3 ACME EI778 ('48) Coated
 
      Ektar 203mm /7.7 EE1384 ('44) Coated
 
Ektar 50mm f/3.5
(Retina) CR
EO25826 ('46) 

Coated

Ektar 203mm /7.7 EE1384 ('47) Coated
Ektar 78mm f/3.5
(Prototype)
ES0001 ('47) Coated
Ektar 203mm /7.7 EI1524 ('48) Coated
Ektar 78mm f/3.5
(Chevron) KSR
RM2747 ('53) Coated
Ektar 203mm /7.7 RA763 ('53) Coated
      Ektar 203mm /7.7 SC RT385 ('59) Coated
WF Ektar 80mm f/6.3 EI810('48) Coated
 
     
WF Ektar 80mm f/6.3 EI908 ('48) Coated
 
Commercial Ektar 10" f/6.3 ACME OS163 ('67) Coated
 
WF Ektar 80mm f/6.3 EI1048('48) Coated
 
     

* Anastigmat Specials were essentially the same as Anastars, but earlier ones were uncoated. Glass compounds in the Anastars may have been updated.   
Although this lens is not marked with , it has the same characteristic color as the other '46 FAS.
   † Prior to 1940, Kodak used a numeric serial number for lenses, but I have seen so few of these that I know nothing about the
    structure of the numbering system
or the
pattern to their assignment.
  ‡ On the Kodak Reflex II, the lens identification is not stamped or engraved on the retaining ring for the front element, but on
    on the outer metal rim of the lens mount which is a cast aluminum piece with cogs that serve as the focusing interface between
    the viewing and the taking lens
. The lens ID information does not include a serial number, unique I think, for KASs and Anastars.
I know of two examples of this lens that have a '0' or 'O' prefix, but I have no information about its significance.

EFP
Ektra focal plane shutter
GSC
GRAPHIC Synchro Compur shutter
KOD Kodamatic Shutter
SC   Synchro Compur shutter
KSR Kodak Synchro Rapid shutter
CR  Compur Rapid shutter
ACME Acme Shutter

  TENTATIVE CONCLUSIONS  
  • Visible differences between uncoated, softcoated and hardcoated Kodak lenses were relatively subtle between 1940 and 1965 when compared to the appearance of modern multi-coated lenses, but some differences in coloration of reflections should be noticeable.
  • While hardcoating of Kodak lenses may have begun as early as 1940, this wasn't generally discussed in public documents until 1946, when the term Lumenizing emerged.
  • Regardless of the presence of hardcoating in a growing fraction of advanced amateur and professional lenses from 1941 through 1945, few had the Lumenizing mark before 1945.
  • The only collector reporting any pattern in hardcoating prior to 1946 is Michael Briggs, a collector of Aero Ektars, who has noticed that most were hardcoated. Some elements have a yellowish-brown color, which he suggests may have become that color over time due to radioactive properties in some of the glasses used. Some of this coloration may have been intended to increase haze reduction in these aerial lenses.
  • All Ektra Ektars, the Ektars in Medalists, the Ektars in Bantam Specials made after about 1940, and large format Eastman Ektars made after about 1940, at a minimum, had soft calcium fluoride coating applied to inner surfaces. When harder fluroides were introduced to particular models, these would have replaced calcium fluoride.
  • The single example of an Ektra Ektar made on or after 1946 was not hard coated. Ektra Owners: More data would obviously be useful. The serial numbers on Ektra Ektars are not on the lens ring, but are stamped in the metal on the shank of the lens that is placed in the camera's lens mount. So far it isn't clear whether Kodak embossed the on hardcoated Ektra Ektars.
  • How were the serial numbers assigned? Sequentially by year or sequentially by lens model? Given the relatively high serial numbers of some lenses, and that Kodak probably wanted a unique number on each lens, it appears to me that a single annual sequence was used. To have assigned numbers by model, would have produced many duplicate numbers and made public use of these as identifying numbers very confusing. If lens rings were produced in a single shop, they likely would have been produced in batches. Perhaps, if the shop were going to make 50 rings for 80mm WF Ektars, they took the last number used and started their run from that point. If production was more dispersed or done in parallel operations, perhaps they assigned ranges of numbers based on projected production. Note the close proximity of numbers in many cases for lenses of the same type and year. An experienced Ektra collector has developed some hypotheses about Kodak serial numbering   .
   

Send lens information to:
  
   

     
   
 
 
Ektar Home Page
Kodak Lens Index  
 
About Ektar lens data
Kodak Lens Lineage  
 
Kodak Ektar Summary
Kodak Lens Coating  
 
Kodak Lenses and Shutters © 1939
Kodak Reference Handbook: Lenses, Rangefinders and Shutters section © 1940  
 
Kodak Reference Handbook: Lenses, Rangefinders and Shutters section © 1942, 1945
Data Book on Lenses, Shutters and Portra Lenses, for Revising Kodak Reference Handbook, © 1942, 1945; Second 1946 Printing   
 
Kodak Data Book: Lenses, Shutters and Portra Lenses, Third Edition, (1948)
Kodak Data Book: Lenses, Shutters and Portra Lenses, Fourth Edition, (1952)  
 
Kodak Data Book: Lenses, Shutters and Portra Lenses, Fifth Edition, (1955)
Kodak Professional Handbook, Equipment Section, (1952)  
 
Kodak Data Book: Lenses, Shutters and Portra Lenses, Sixth Edition, (1958)
Kodak Lens Serial Numbers  
 
Enlarging Lenses      
 








This booklet predates the first edition of the
Kodak Reference Handbook and contains detailed information about many more lens models and considerable background information about Kodak lens design and production.

Kodak issued replacement pages to registered owners of the original Kodak Reference Handbook which was published in a loose-leaf binder; the replacement pages contained updated information about new products and processes. Newer versions of the Handbook would have contained these pages.
© dates in this material appear for 1940, 1942, 1943 and 1945 and perhaps other dates. One of the first separately bound Data Books was published in 1946 "For Revising Reference Handbooks," and noted as Second Printing.

 
       

 

10/29/2010 20:44