Types of Lenses/Objectives

Types of Lenses/Objectives

  1. Christopher Walrath

    Christopher Walrath Member

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    Christopher Walrath submitted a new resource:

    Types of Lenses/Objectives - Types of Lenses/Objectives

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    Last edited by a moderator: Feb 6, 2016
  2. jnanian

    jnanian Advertiser Advertiser

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    nice article chris!

    do you have basic diagrams
    for some of these lens designs ?


    thanks!
    john
     
  3. benjiboy

    benjiboy Subscriber

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    That should be Doublet Christopher, not Douplet, sorry to correct you.
     
  4. Christopher Walrath

    Christopher Walrath Member

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    I actually coined the term "DUPLET" from 'Lenses in Photography' by Rudolf Kingslake, former director of optic design for Kodak Eastman Co. A "DOUBLET" is a cemented pair of objectives as you might find in a telescope. But thanks for the eagle eye.
     
    Last edited by a moderator: Oct 3, 2009
  5. benjiboy

    benjiboy Subscriber

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    Sorry Chris, I've never heard the term "douplet" before.
     
  6. jnanian

    jnanian Advertiser Advertiser

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    benjiboy - he said he just made it up :smile:
     
  7. benjiboy

    benjiboy Subscriber

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    That was my first reaction John, but I couldn't understand why someone would write a serious blog about lens design and make up his own words, I thought he was quoting Kingslake's book as his authority
     
  8. Christopher Walrath

    Christopher Walrath Member

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    I was using the term Duplet from the source. I didn't make it up. I would trust a former Kodak head of optics over a wiki-hack (stupidly looked on wiki and found they used doublet). But Kingslake specifies that Doublet used in this fashion is ERRONEOUS. Please, do not mar this with thread with this argument any further. You imply it is not a proper term because you have never heard of it. Guaranteed you have many terms and such that I have never heard of and that does not debunk them in the least. Now, on to the regular answers.
     
    Last edited by a moderator: Oct 5, 2009
  9. jnanian

    jnanian Advertiser Advertiser

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  10. luvcameras

    luvcameras Advertiser Advertiser

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    Kingslake did in fact use the term "Duplet." Just search google; Duplet Kingslake.

    Dan
     
  11. benjiboy

    benjiboy Subscriber

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    I had really never heard of the term "Douplet" before "Doublet or Cemented doublet "is a much more common optical term for two lenses cemented together with , I thought it was an error.
     
  12. Christopher Walrath

    Christopher Walrath Member

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    DOUBLET is the correct term for a cemented lens pair. In a DUPLET lens system there are two groups of lenses separated by a space, and successive lenses in each group are in contact; not cemented together. I wrote this article upon reading a few different books I have picked up over the past couple of years in an attempt to deepen my knowledge of photography and the means we use to the end of the photograph. I just hope everyone gets a little bit of 'I didn't know that' from this article as I have from reading the material that inspired it.

    Oh, and the coin thing. Yeah, I misused the word. I was thinking 'To coin the phrase' and got tunnel visioned into the word coin. So, yeah, that was my bad. I hope you all will be understanding. Not like I've been accused of being confusing before. ;p
     
  13. Christopher Walrath

    Christopher Walrath Member

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    And to answer John's question publicly, I made a few crude bmp files on some of the lens designs but I do not think there is a way to upload photos form my PC to a thread. So, I do not have anything available to show.
     
  14. Sirius Glass

    Sirius Glass Subscriber

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    My favorite expression. :D

    Steve
     
  15. lens_hacker

    lens_hacker Member

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    I just found "Lenses in Photography", Rudolf Kingslake, 1951 in a good used bookstore today. The optical block diagrams given in the book make it easy to see how a "duplet" is on a different level than a "doublet". Kingslake defines a duplet as "two components with a central stop, often symmetrical". A doublet refers to a cemented lens pair. A duplet can be a pair of single-element lenses, doublets, or triplets. A singlet can be composed of a single element lens or a cemented group. It's more than just how many elements and groups are in an optic, but more describes their layout.

    Kingslake also writes about Aspheric Optics, and the manufacturing challenges that need to be overcome to produce them. Great book from a Brilliant mind.
     
  16. Christopher Walrath

    Christopher Walrath Member

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    Wow, someone else with as much time on their hands as I have. It is a great read. And thanks for reading the article.
     
  17. Efaron

    Efaron Member

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    Dear Christopher
    Please correct at the end of this very interesting article 2 words: they should be "Anastigmatic" and "astigmatism"... as far as I know.
    Best regards and thanks again

    edmond
     
  18. ic-racer

    ic-racer Member

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    Most zooms I am familiar with are big and heavy. Or at least bigger and heavier than prime lenses of similar performance.
     
  19. Monito

    Monito Member

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    The article is a good read and has much good information. However, I think it makes a common error and confuses "telephoto" with "long focus" (long focal length). All telephoto lenses are long focus, but not all long focus lenses are telephoto.

    The telephoto concept is a long focus lens that has the optics arranged to shorten the overall length of the barrel to about two-thirds the size it would be if it were a simple long focal length design (without resorting to catadiatropic (mirror) lens designs).
     
  20. Sirius Glass

    Sirius Glass Subscriber

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    A great explanation is nontechnical terms. Well done.