Looking for a technical term

Discussion in 'Film Discussion and Q & A' started by LaFoto, Oct 28, 2007.

  1. LaFoto

    LaFoto Just Corinna in real life Staff Member Supporting Member

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    When the front glass of a lens does NOT turn while you adjust your range or focus, this very feature is called "Geradführung" in German. Meaning the lens stays "straight". What is the English term for this very feature. One word. Just that one word describing this feature and you are my friend! :heart: :hail::heart:
     
  2. Alpha

    Alpha Troll Extraordinaire

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    Fixed? When does the front element ever turn? I've never heard of that...
     
  3. frXnz kafka

    frXnz kafka TPF Noob!

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    Both of my zoom lenses do this (a Sigma and a Promaster lens, both fairly low end lenses), and I know that the Canon Rebel kit lenses do this. My prime lens, however, is "fixed"

    EDIT: I should mention, the front element only moves when adjusting focus, not when adjusting focal length. I'm not sure if this is what lafoto had in mind.
     
  4. Alpha

    Alpha Troll Extraordinaire

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    Hmmm...you're right about zooms. Forgot about them, I never use them anymore. Dunno why the front element of a prime would rotate though...
     
  5. doobs

    doobs TPF Noob!

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  6. LaFoto

    LaFoto Just Corinna in real life Staff Member Supporting Member

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    Straight-line sounds good! Thanks for that! Straight-line motion sounds even better. OK, that link goes into my favourites, too. Thanks a lot :hugs: and :heart: and :hail: for your help (and this text is about Leitz lenses from the Thirties, so straight-line motion is normal today but wasn't ALWAYS normal; at one point in time it was a big new feature!)
     
  7. Digital Matt

    Digital Matt alter ego: Analog Matt

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    I've always heard this referred to as internal focusing.
     
  8. Joxby

    Joxby TPF Noob!

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    I dont think there is a word to describe what you mean, it will take more than one word in English.
    Likely as not, "straight line" will mean about as much as "Geradführung" to average English speaking PhotoJoe.
    Why not describe it as "does not rotate during focus"
    At least they won't be asking what straight line means:mrgreen:
     
  9. skieur

    skieur TPF Noob!

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    Geradfuhrung means "slide" and that is exactly what the front element does on some zooms. It slides forward and backward to go from one focal length to another and turns for focus.

    The process of sliding it backward or forward while shooting is refered to as "pulling focus" in English as in you are changing the distance area that is in focus by changing the focal length.

    skieur
     
  10. LaFoto

    LaFoto Just Corinna in real life Staff Member Supporting Member

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    Thank you all ... but keep in mind that I am not talking about zoom lenses. They were unheard of in the Thirties, and Leitz Company was happy enough to develop their fast 35, 50 and 85mm prime lenses (1:2) in the "Geradführung"-version. And the text does not give me room to use a definition instead of the word... there must be a term for this feature in a lens in English ... and for th time being I am going with "straight-line motion", since the front glass does not turn, i.e. filters can stay like they were set and need not be readjusted. In the end, the client might KNOW the one word in question, it is one word out of 9 pages of tight type-script ... that shouldn't break my neck.
     
  11. Helen B

    Helen B TPF Noob!

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    It doesn't only apply to internal focusing lenses.

    I agree with Joxby. I don't think that there is a single word for it in English. Nikon describe it with a phrase like "filter attachment does not turn during focusing". Maybe "non-rotating front" is the best that can be done in English. There used to be quite a few primes for which the filter ring turned while focusing, including all the front-cell focusing ones.

    Best,
    Helen
     
  12. doobs

    doobs TPF Noob!

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    Ah, now I know what you're talking about, LaFoto. I remember I had a lens that turned like that once, and it was a pain with the circular polarizing filter. Don't remember the name.
     

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