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Thread: Magnifications

  1. #1
    45-57-617
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    Magnifications

    Hello and greetings to you all.

    I have a question... (obviously!)

    If I have a lens (lets say a 150mm lens) on a 4x5 camera and I take a head-and-shoulders portrait. The subject is say 1m from the camera.

    OK. I put these figures into the Bob Atkins DOF calculator ... and I get a certain 'magnification'.

    If I want exactly the same image but on 5x7 film on a 210mm lens what will be the 'magnification' ? ... and the same again for a 300mm lens on an 8x10 camera...

    I'm certain someone knows this ...

    Do I get his magnification figure off the DOF calc and multiply the 4x5 figure by 7/5 for the 5x7 and 10/5 for the 8x10 ?

    Cheers.

  2. #2

    Re: Magnifications

    You can't really get "exactly the same picture" since the formats have different ratios.

  3. #3
    unexposed darr's Avatar
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    Apr 2005
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    1,804

    Re: Magnifications

    I think you are actually talking about 'angle of view'. Use this for calculating what you know for the 4x5 with the 150 and then calculate the lens+format for the others and compare the view for the horizontal and vertical angles.

    http://www.mat.uc.pt/~rps/photos/angles.html

  4. #4
    45-57-617
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    Re: Magnifications

    Oh all right then ...

    Instead of 'exactly' insert the word pretty 'much the same' ... :-)

    Thanks Darr. I think it might be. I'm trying to understand the DOF for the same image on various formats.

    Cheers,

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