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Thread: The term for "lens does not extend during zooming"?

  1. #1
    Deregistered wongjunhao's Avatar
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    Default The term for "lens does not extend during zooming"?

    Hi, some of the zoom lens have this feature that the lens barrel does not extend during zooming. May I know what is the term use for that?

    Pardon if the question sounds stupid because I'm new to photography.
    Please be nice.

    Thanks.

  2. #2

    Default Re: The term for "lens does not extend during zooming"?

    I think should be internal focusing.

  3. #3
    Senior Member ZerocoolAstra's Avatar
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    Default Re: The term for "lens does not extend during zooming"?

    I was thinking of Internal Focusing (IF), but you're asking about zooming... hmmmmmm......
    Exploring! :)

  4. #4

    Default Re: The term for "lens does not extend during zooming"?

    Internal zoom?
    Alpha

  5. #5
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    Default Re: The term for "lens does not extend during zooming"?

    It's definitely not internal focusing because that pertains to not extending when focusing.

    I don't think there is a phrase, which is why lens marketing blurb has more or less the same text as you used.

  6. #6
    Senior Member Diavonex's Avatar
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    Default Re: The term for "lens does not extend during zooming"?

    It's call internal zoom.

    I read somewhere that a mirror is use to turn the light at right angle to achieve a reasonable zoom level in a compact/slim enviroment.

    Use mainly in ultra-compact camera.
    Last edited by Diavonex; 13th January 2010 at 11:11 PM.

  7. #7
    Deregistered wongjunhao's Avatar
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    Default Re: The term for "lens does not extend during zooming"?

    Thanks for the replies. "Internal zoom" sounds right.

    If only every lens has internal zoom, that would be great.

  8. #8
    Member sf_kang's Avatar
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    Default Re: The term for "lens does not extend during zooming"?

    This has to do with the design of the zoom lens. On some zoom lens, the lens barrel actually extends further and further during the 'zooming', i.e. the overall lens become longer. For the better zoom lens, the designers have managed to achieve the zooming effect while keeping the length of the lens constant (meaning lens barrel does not extend) during the zooming. This is prefered and makes handling more pleasant. For closeup work, it keeps the lens to subject distance unchanged throughout the zoom range. Most of the better and pro zoom lens would have this feature, e.g. the Nikkor AF-S VR 70-200mm/f2.8G, the physical outer dimensions of the lens remain unchanged throughout the zoom range. Hope this helps.
    Fred

  9. #9
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    Default Re: The term for "lens does not extend during zooming"?

    I heart internal zooming fast lenses.

  10. #10

    Default Re: The term for "lens does not extend during zooming"?

    yes the term is internal zoom.

    nikkor 70-200mm f/2.8 VR is one example of an internal zoom lens.

  11. #11

    Default Re: The term for "lens does not extend during zooming"?

    Quote Originally Posted by ahbian View Post
    I think should be internal focusing.
    ah.. i stand corrected.

  12. #12

    Default Re: The term for "lens does not extend during zooming"?

    Internal zoom + internal focus + non-rotating front element =

  13. #13
    Member akszaksz's Avatar
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    Default Re: The term for "lens does not extend during zooming"?

    i'm using tamron 17-50, when focusing, the length of the lens barrel does not change. Unlike my previous kit lens or 50mm prime lens, when focusing, then len barrel extend in & out.

    So i suppose the features you mentioned is the same concept, but zooming(also including focusing) instead of focusing?
    meaning the len barrel won't be extended when u do zooming or focusing, everything is internaly within the len barrel.
    http://www.akkuaphotography.com

  14. #14

    Default Re: The term for "lens does not extend during zooming"?

    Is internal focusing same as parfocal ???

  15. #15

    Default Re: The term for "lens does not extend during zooming"?

    Quote Originally Posted by CamInit View Post
    Is internal focusing same as parfocal ???
    No. Please click and read:

    http://www.lmgtfy.com/?q=parfocal
    Alpha

  16. #16

    Default Re: The term for "lens does not extend during zooming"?

    So in summary,

    Internal focusing = no change in physical length of lens barrel at different focus

    Internal zoom = no change in physical length of lens barrel at different focal lengths

    Parfocal = no change in focus at different focal lengths

    so, i gather that a lens with internal zoom + internal focus + non-rotating front element can theoretically be made by encasing any zoom lens in a large enough barrel?

  17. #17

    Default Re: The term for "lens does not extend during zooming"?

    Quote Originally Posted by CamInit View Post

    so, i gather that a lens with internal zoom + internal focus + non-rotating front element can theoretically be made by encasing any zoom lens in a large enough barrel?
    Nope. You need to factor in the wide angle requirements too.
    Alpha

  18. #18

    Default Re: The term for "lens does not extend during zooming"?

    Quote Originally Posted by Rashkae View Post
    Nope. You need to factor in the wide angle requirements too.
    Hmm... ah, I see. Make that a really fat barrel then... haha...

  19. #19
    Deregistered allenleonhart's Avatar
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    Default Re: The term for "lens does not extend during zooming"?

    cant help it. if u want good stuff its big one:x

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