Using MTF for control the details class , Leica MTF Analysis

Discussion in 'Alternative Processes' started by Mustafa Umut Sarac, Aug 24, 2011.

  1. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    If you look to Leica and Leitz MTF charts two things are common.

    First , at 5.6 , 40 and 20 lp mm sagittal contrast graph dives deep at the 2/3 far from the center and tangential graph get force and gets higher at this zone.

    Second at f :2.8 , sagittal contrast curve lower than the f :5.6 but tangential curve is faraway stronger than the sagittal.

    With looking many Leica shots including mine , Leica gives immense skin tone details at the dark and the vains , shadows , light , skin texture , bones under the skin , gives a super detail and everything looks blobs from the surface at wide open.

    I suspect this is a result of 40 lpmm , tangential curves immense contrast compared to sagittal.

    I am thinking that this is one of the Leicas 70 year old tradition and they never step back from this.

    I read a book on modulation transfer and if the high detail sagittal lines and tangential lines comes together , they make a criss cross pattern and blur the image.

    Thats why all Leicas have if sagittal up , tangential lower and tangential up , sagittal lower especially at dark.

    I found higher contrast places cast on the print when two eyes look directly to picture. Not at the center but little bit right , little bit left.

    I think taking two pictures with the attention of MTF chart and make one positive one negative films and printing together , increases detail content with control.

    I believe tangenial curve of Leica is a thing gotten from engraving. It gives engraving details and difficult to render details visible because its subject is tangential details.

    Leica Chief designer says nobody can do what Leica do.

    May be its easy to find MTF curve from lens data but finding final design from final mtf graph is difficult.

    Look 35 mm Summicron MTF Graph.

    Umut
    Istanbul
     
  2. ic-racer

    ic-racer Member

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    ?? I have never read it that way.

    If the saggital and tangential are the same it means the Airy disks and circles of confusion are actually projected on the film plane as round circles. When the sagittal and tangental MTF are not the same it is because the Airy disks and circles of confusion are oblong, with the greater MTF perpendicular to the short axis of the ellipse.
     
  3. Mustafa Umut Sarac

    Mustafa Umut Sarac Member

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    ic-racer ,

    I read the same thing for the equal tangential and sagittal lines but book adds that round circles blur the image.

    Umut
     
  4. ic-racer

    ic-racer Member

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    Ok I see that if we say that the circles maintain the same area, then I guess I would agree that as they get more oblong the tangental MTF would be greater at the edges.

    Another thing to consider is the viewer's eyesight. Are you sure you don't have any radial astigmatism in your own eye which may make you prefer certain images?