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x10, x12, x18 and all that

Discussion in 'Camcorders, Action Cams & Video Editing Forum' started by roman700, Sep 21, 2004.

  1. roman700

    roman700
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    How would you describe these figures in layman's terms? Something like an optical zoom of x10 means that you can zoom in so you magnify what you were looking at by 10?
     
  2. MarkE19

    MarkE19
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    You've answered your own question there!
    10x zoom lens does mean that you can zoom in and magnify the shot by 10x

    Mark.
     
  3. roman700

    roman700
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    Thanks for the verification!
     
  4. Roy Mallard

    Roy Mallard
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    In comparison to the human eye this will be about 8x magnification.

    The standard (i.e. where a lens presents a subject in the same way that is percieved by the human eye in terms of perspective) is usually taken at 50mm.

    Most camcorders with built in lenses (i.e. not professional with interchangable lenses) have a wide angle of around 40mm, so it is slightly wider than we would percieve an object, therefore a 10x zoom has roughly the effect of 8x the human perspective.

    Unless you are using a tripod, beyond 10x zoom is pretty unworkable.

    There is also more to it in terms of how lenses flatten (telephoto) or stretch (wide) a subject and how the depth of focus decreases as a lens focal length increases (independantly of aperture).

    Bigger isn't always better, domestic camcorders with more than 10x usually suffer from chromatic abberation ('fringing', coloured halos around the subject) and even with a zoom range of 10 there will be pincushion distortion and barrell distorion at opposite ends of the zoom.

    The other advice is to avoid digital zooms at all costs.
     
  5. Roy Mallard

    Roy Mallard
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    I should point out that when I say 40mm, 50mm etc I am talking about 35mm equivalents, camcorders ccd chips are much smaller than a slide of film, so smaller focal lengths equate to the same thing.
     
  6. roman700

    roman700
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    Thanks Roy, this is great.
     

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