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Thread: question about calculation of close up magnification

  1. #1
    Senior Member denniskee's Avatar
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    Default question about calculation of close up magnification

    Close up of the word "FIFTY" on a 50cents coin.


    Reverse mount 58mm lens onto Sony DSC 707 at full optical 48.5mm zoom or 190mm in 135 film format.

    Calculation of the magnification factor for a 135 format film camera,

    focal length of lens mounted to camera / focal length of the lens thats reverse mounted.

    So in this case, should it be 190 / 58 or 48.5 / 58?

    I am thinking it cant be 190 / 58 = 3.2x mag factor.

    It looks more like 48.5 / 58 = 0.8x mag factor (which in this case reduction factor).

    Pls help.

    Thanks.
    Last edited by denniskee; 8th February 2010 at 05:40 AM.
    photography makes one sees things from all angles.

  2. #2
    Senior Member denniskee's Avatar
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    Default Re: question about calculation of close up magnification

    anyone? pls help.
    photography makes one sees things from all angles.

  3. #3
    Senior Member denniskee's Avatar
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    Default Re: question about calculation of close up magnification

    just found out, the 707 sensor size is 8.8mm x 6.6 mm.

    the length of the wording is about 11mm

    so the converter factor is 8.8 / 11 = 0.8x.
    photography makes one sees things from all angles.

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