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  1. #41
    winjeel's Avatar
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    Mar 2009
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    central Japan
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    I thought there were easier ways to copy slides / film. I was young back in the days when copying film was done. Now everyone around me just "right clicks" it, so I have nothing but a distant and foggy memory of how that sort of thing was done.
    Film and digital; best of both worlds. JapanesePhotos.Asia.

  2. #42

    Join Date
    Oct 2006
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    I'm not sure of the answer in terms of brand/model designation. However, from optical theory the best solution for 1:1 copying would be a truly symmetrical lens because at 1:1 magnification certain aberrations, such as coma, lateral color, and distortion are automatically canceled out by symmetry.

    If the designer chooses the elements of the design such that the Petzval sum is zero then one has at least the possibility to simultaneously eliminate astigmatism and curvature of field.

    I have played around with the computer program Winlens to generate theoretical designs for lenses for 1:1 copying that correct for all the Seidel aberrations. If one allows the use of two aspherical surfaces then one can design a theoretical achromat that is diffraction-limited over a limited field angle and for a single wavelength. It is limited by secondary color at other wavelengths. (However, if one were to also use ultra-low dispersion glasses then secondary color could also be brought to a minimum.) The f-number of such a lens would be modest - something like f/4.0 or 5.6.

    A real lens designer (not me) could probably do somewhat better.

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