C P Goerz AG Dagor f= 30 cm 1:6,8 and f=36 cm 1:7,7 Design Paper 2016-02-07

C P Goerz AG Dagor f= 30 cm 1:6,8 and f=36 cm 1:7,7 Design Paper

  1. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Last edited by a moderator: Feb 6, 2016
  2. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    goerz dagor 360.JPG

    dagor 360 2.JPG

    dagor 300.JPG
     
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  3. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    dagor02.jpg

    dagor 03.jpg
     
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  4. E. von Hoegh

    E. von Hoegh Member

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    I have the 30cm f:6.8, a late one #657010. Thank you for finding this!
     
  5. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Hello E. von Hoegh,

    Can you please share your best quality shots for evaluating the lens,

    Thank you.
     
  6. E. von Hoegh

    E. von Hoegh Member

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    I'm sorry, I have no way to scan negatives at anything approaching the quality neccesary to evaluate the lens' performance.
    But I can say I've been using it for about 20 years, with b&w and some color transparency - Kodachrome 64 in 120 size for product photography, in the studio - and it's a superb example of a Dagor.
     
  7. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    I am attaching the above paper for APUG malfunction. My two attached images of lenses have been crashed in 3 hours , I dont know why ?

    Here is the same paper again attached below.

    Umut
     

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  8. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Thank you, no problem , Someone had been asked at an another forum that can he evaluate an Stradivari from mp3. No ! But however I can discriminate Leica shots at the gallery. Difference is more than the difference of compression IMHO.

    From that view , anyone is welcome to put her his images. These last articles is my crusade againts the science and practice of lens design.
    New books are tragedy. They are extremelly expensive and each others copies.

    Von Hoegh , You remember my last post on Leica secret , you put interesting post , can you shed more light on some lens elements and their select high aberrations as a tool of low contrast unsharp mask ?

    Thank you.
     
  9. E. von Hoegh

    E. von Hoegh Member

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    Here you go Mustafa, the US patent #528155 for the Dagor. Note the two constructions covered, the one on the right is known as the "reverse Dagor" - also used in the Zeiss Doppel Amatar and the Schneider-Kreuznach Angulon.

    http://ip.com/pat/US528155 You have to click on the "download" box and enter a captcha code.
     
  10. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Thank you. US patent 528155 is dated from 1894. I will read it and comment.

    I attached that pdf patent file herebelow.
     

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  11. E. von Hoegh

    E. von Hoegh Member

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    I also have an earlier CPG Berlin Dagor, a 240mm #260383. I'm pretty sure this one was made after the lens was recalculated to use newly available types of glass, but maybe not. It behaves very much the same as the 30cm.
    Inoticed the date on your drawings, 1926. This was very close to the date Zeiss acquired Goerz and formed Zeiss-Ikon in 1926.
     
  12. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Wonderful ! If you noticed , there are writings per lens , one with ink pen and newer one with the carbon pencil. I saw BAF at one of the later written pencil notes. BAF reminds me Barium Fluoride . Do you know when BAF invented , I invested to google but could not find.
    If later lenses is fluoride based , they say they are very sensitive to atmosphere. I have 111mm f:1.5 Fluro Ektar and 10 pounds weight and what an amazing lens. I advise you to hold your lenses with hand and look to someone at night. If you see the detail , noise , plasticity , shadow , skin detail increase , curves are more visible , you would notice that your lens sees more than the eye.
     
  13. Dan Fromm

    Dan Fromm Member

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    E, you really should take a look at Eric Beltrando's site www.dioptrique.info. He has prescriptions for > 1,000 lenses, including some made by Goerz and Dagor clones from other makers, taken from patents and, in the case of Boyer lenses, Boyer's archives.

    Eric wrote a ray-tracing program 030 that may still be available for download. He used it to evaluate lenses in a variety of ways, the results are posted with the prescriptions. Mustafa, you may find the spot diagrams illuminating.
     
  14. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    Dan,

    I had been contacted with that gentleman years ago , but I had lost the address. Thank you reminding that one of the best site on web.
    I want to ask , what does it mean that final negative coma analysis final result from one example lens. Does it mean there is still a error , or does it mean there is a excellence ?
    I cant wait , I will open a thread. And how do we need to comment on spot diagrams ?

    Umut
     
  15. darkosaric

    darkosaric Subscriber

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    This is impressive site! I would not be surprised if LOMO guys are already looking in this site and searching what to resurrect next after success of Petzval project :smile:.