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  • zoom mechanism in camera

    Discussion in 'The main mechanical design forum' started by zubair, Jun 20, 2012.

    1. zubair

      zubair Member

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      Hi All!
      I am studying about zoom cameras nowadays. But i want the opinion of anyone expert in this field or working in this field regarding the suitable mechanism used for providing zoom motion to more than one group of lenses in opposite directions.
       
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    3. Erich

      Erich Well-Known Member

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      I'm not an expert and I don't play one on television, but I would rotate a sleeve with left hand threads at one end and right hand threads at the opposite. One group of lenses would have left threads, other have right. Restrain the lenses from rotating, but allow axial motion. Rotating the ring will move the lenses in opposite directions.
       
    4. zubair

      zubair Member

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      Thanks Erich for your interest..........
      I want to drive two group of lenses simultaneously by stepper motor..........and want this motion quick and smooth...I am thinking about using ball screw...though using it first time and on hit and trial.........What you suggest?
       
    5. Erich

      Erich Well-Known Member

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      Ball screws provide accurate, no backlash, low friction motion. All features that would be helpful in locating optics.
      They are also expensive, and take up a lot of space, two things that would not be appreciated in a lens design.

      I guess I don't understand your application well enough to provide useful advice.
       
    6. zotzman

      zotzman New Member

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      Why do the lenses need to be prevented from rotating?
       
    7. Erich

      Erich Well-Known Member

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      It is a requirement of the mechanism concept I was explaining. My design is analogous to rotating a nut to make a screw translate.
      If you allow the screw to rotate, it will rotate with the nut and you get no translation. Prevent rotation, but allow translation and you get a mechanism that works.
       

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