[rollei_list] Re: Rollei 35S, SE

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Wed, 3 Oct 2007 05:51:54 -0700
----- Original Message ----- From: "Eric Goldstein" <egoldste@xxxxxxxxx> 
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, October 03, 2007 5:22 AM
Subject: [rollei_list] Re: Rollei 35S, SE
I'll have to recheck Kingslake... from memory I think he diagrams the lens as a 7 element double-gauss, similar to the much heralded Summicron when first introduced in the early 50s. As an uncoated pre-war lens, that would be many many glass-air surfaces... Kodak must 
have known lens coatings were just around the corner...


Eric Goldstein
The diagram in the Kodak lens booklet shows a six element conventional Biotar or Opic type. I can't find this lens in LensView but I may be able to find something in a Google patent search. The earliest Kodak Biotar in LensView is a patent applied for in 1937 and issued in 1940, from the diagram its not the same lens although it is an f/2 lens. I don't think Kingslake shows the Bantam Special lens. I don't know if the earlier versions of this lens were coated but the 1946 printing of the 1945 edition states that the Bantam lens and the Medalist lens are "treated on glass air surfaces to reduce flare." This may be a hard coating but Kodak was applying soft coating to the inner surfaces of lenses from about 1940. This is from a _Kodak Reference Handbook_ I bought at a sale last week-end. It has several Kodak bulletins in it, one of which is for _Kodak Luminized Enlarging Lenses_. If I read the date code on the back right it was published 5-48. It shows a picture of a vacumm coating machine and a very brief description of coating. I am pretty sure Kodak began using the trade-name of "Luminized" about 1946, however, its not used in the booklet described above. However, there is a slight revision of the text from the 1945 edition: the lenses called Eastman Ektars (later called Kodak Commercial Ektars) are described as having anti-flare coatings on _inner_ glass-air surfaces in the older edition and simply as being treated for anti-flare in the later edition, leading me to believe that these were hard coatings even though the name "Luminized" was not yet applied. Further, Kodak was one of the primary companies involved in the research into anti-reflection coating during WW-2. Kodak and RCA were very early developers of various means of lens coating going back to the early 1930's. RCA's interest may have been due to its interest in photographic sound recording. In any case, there are some early articles on coating in the _RCA Review_, RCA's scientific house organ. Zeiss had developed a method of vacuum coating about 1935 but I don't think it was hard coating. The trick of baking the coating in vacuo in the coating machine was developed during WW-2 as part of the Signal Corps research. 

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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