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Thread: How do you determine the optical magnification of lenses?

  1. #1
    Member marsulein's Avatar
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    Default How do you determine the optical magnification of lenses?

    Dear Photo Enthusiasts,

    I've just picked up photography roughly 2 weeks ago and I am still very confused on how do you actually find out the optical magnification (a.k.a zoom) just by reading about the lens spec.

    For example, let's take a look at this lens which I found from official Nikon website:

    AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED

    The website says that:

    "AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED, a compact, lightweight 11.1x zoom lens that is ideal..."

    How do you actually derived the 11.1x magnification from looking at the focal length information?

    A very confused Noob,
    Mar

  2. #2
    Member/Tangshooter Redsun's Avatar
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    Default Re: How do you determine the optical magnification of lenses?

    Quote Originally Posted by marsulein View Post
    Dear Photo Enthusiasts,

    I've just picked up photography roughly 2 weeks ago and I am still very confused on how do you actually find out the optical magnification (a.k.a zoom) just by reading about the lens spec.

    For example, let's take a look at this lens which I found from official Nikon website:

    AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED

    The website says that:

    "AF-S DX VR Zoom-Nikkor 18-200mm f/3.5-5.6G IF-ED, a compact, lightweight 11.1x zoom lens that is ideal..."

    How do you actually derived the 11.1x magnification from looking at the focal length information?

    A very confused Noob,
    Mar
    they actually got the 11.1x zoom factor by dividing 200/18

  3. #3

    Default Re: How do you determine the optical magnification of lenses?

    =200/18
    =11.1

  4. #4

    Default Re: How do you determine the optical magnification of lenses?

    think this thread shld answer most of your qns.

    http://www.clubsnap.com/forums/showthread.php?t=380887

  5. #5
    Moderator Octarine's Avatar
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    Default Re: How do you determine the optical magnification of lenses?

    Quote Originally Posted by aquaobsession View Post
    =200/18
    =11.1
    That means a 70-200 lens has a lower zoom factor than a 17-50? Sounds rather weird and misleading... I prefer the real figures of focal length rather than such marketing bubbles of zoom factor.

  6. #6
    Senior Member zac08's Avatar
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    Default Re: How do you determine the optical magnification of lenses?

    Quote Originally Posted by Octarine View Post
    That means a 70-200 lens has a lower zoom factor than a 17-50? Sounds rather weird and misleading... I prefer the real figures of focal length rather than such marketing bubbles of zoom factor.
    This zoom factor is more for the PnS or Prosumers anyway....

    I dun think any of the SLR users bother with it....
    Michael Lim
    My Flickr Site

  7. #7

    Default Re: How do you determine the optical magnification of lenses?

    Quote Originally Posted by marsulein View Post

    How do you actually derived the 11.1x magnification from looking at the focal length information?
    simply put, the most direct answer is 200/18

    the maximum focal length on the lens, divided by the minimum

    same goes for any p&s, but you shouldn't care about focal lengths, more about perspective.

  8. #8
    Member marsulein's Avatar
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    Default Re: How do you determine the optical magnification of lenses?

    Thanks for the overwhelming response!! Truly appreciate that.

    I particulary love the link in this thread, simple and not packed with all those confusing figures. Just what I am looking for!!

    Quote Originally Posted by flipfreak View Post
    think this thread shld answer most of your qns.

    http://www.clubsnap.com/forums/showthread.php?t=380887

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