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Thread: How to find the nodal point of a lens?

  1. #1

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    How to find the nodal point of a lens?

    I have a panorama project in mind. I'd like to pan the view camera from the nodal point of the lens. Is there a way to calculate the nodal point precisely, or would estimaing the middle -- i.e., the point between the front and back glass surfaces -- be close enough?

    TIA

  2. #2
    Big Negs Rock!
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    Re: How to find the nodal point of a lens?

    An easy way to find the nodal point of the lens is to put two vertical elements in front of the lens. Move the camera back or forward until the two verticals don't move in relationship to each other.
    Mark Woods

    Large Format B&W
    Cinematography Mentor at the American Film Institute
    President of the Pasadena Society of Artists
    Director of Photography
    Pasadena, CA
    www.markwoods.com

  3. #3

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    Re: How to find the nodal point of a lens?

    Quote Originally Posted by Mark Woods View Post
    An easy way to find the nodal point of the lens is to put two vertical elements in front of the lens. Move the camera back or forward until the two verticals don't move in relationship to each other.
    I'm probably dense (most people say so), but I don't understand. How does that tell me where the optical center of the lens is?

  4. #4
    Lachlan 717
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    Re: How to find the nodal point of a lens?

    Try pivoting around the iris in the shutter, assuming a) the lens has a shutter, and b) the lens isn't a telephoto design.
    Lachlan.

    You miss 100% of the shots you never take. -- Wayne Gretzky

  5. #5

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    Re: How to find the nodal point of a lens?

    Hi Marco,

    Here is a website that shows images / text of what Professor Woods was describing.

    http://dgrin.smugmug.com/gallery/2114189

    Good Luck & Regards,

    Tim

  6. #6

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    Re: How to find the nodal point of a lens?

    if it is a schneider lens, you can also get the information from their data sheets - which they have very conveniently posted on line.

  7. #7

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    Re: How to find the nodal point of a lens?

    How to find the nodal point

    Hello from France and welcome to the Entrance Pupil Club !
    The proper position of rotation of the whole camera for panoramic stitching is the entrance pupil of the lens and nowhere else.

    It is somethimes specified in manufacturers's data sheet (e.g. Zeiss medium format lenses, Schneider large format lenses, ...) but the best is use an experimental procedure as explained by Alain Hamblenne (in English and French)
    http://www.outline.be/quicktime/tuto/
    http://www.outline.be/quicktime/tuto/TheGrid.pdf English tutorial

    http://www.outline.be/quicktime/tuto/LaGrille.pdf
    Same in French.

    More readings about "Why is it the entrance pupil and nowhere else" a favourite discussion on our forum !
    http://www.largeformatphotography.in...pupil+entrance

    A geometrical proof (for those who like geometrical optics and hand-crafted ray tracings )
    http://farm2.static.flickr.com/1156/...8019c2f8_d.jpg
    http://farm2.static.flickr.com/1122/...bc05f5d2_d.jpg

  8. #8

    Re: How to find the nodal point of a lens?

    If this is an outdoor project and the scene is more then 150 yards from the camera then you don't need to rotate around the nodal point. If you are doing interiors then you do.
    Mark is right, that is the simple way to find the nodal point. Two vertical lines and then rotate the camera so one does not rotate in relation to the other. If they do move the point of rotation towards or away till they do not move when you rotate the camera.

  9. #9

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    Re: How to find the nodal point of a lens?

    Thanks all, for many good answers.

  10. #10

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    Re: How to find the nodal point of a lens?

    It is simply adequate to rotate aound the lens aperture, that has to work or the aperture would cause a distortion. I have done this successfully for several decades.

    Lynn

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