Have I found the nodal point? (PTGui shift-question)

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Thread: Have I found the nodal point? (PTGui shift-question)

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  1. Have I found the nodal point? (PTGui shift-question)

    #1

    I've spent days trying to get the nodal point right on my Canon EOS 20D/Sigma 10-20. I use PTGui as stitching software. No matter what I did I couldn't get rid of what seemed to be parallax errors. Then I suddenly discovered the advanced settings on the optimizer-tab, when I checked "Field of view", "a", "b", "c", "Horizontal shift" and "Vertical shift" under "Optimize globally" all of my panoramas got perfect (PTGui says "Too good to be true" when optimizing). Now I wonder if I actually have got the nodal point right or if there still is something wrong with my Nodal Ninja-settings that's getting corrected in the software? I want as much as possible to be optimized with hardware and not by some more or less "inaccurate" software-algorithm. Do you have problems stitching panoramas with PTGui without optimizing the horizontal/vertical shift?
  2. Re: Have I found the nodal point? (PTGui shift-question)

    #2

    Quote Originally Posted by irrbloss View Post
    I've spent days trying to get the nodal point right on my Canon EOS 20D/Sigma 10-20. I use PTGui as stitching software. No matter what I did I couldn't get rid of what seemed to be parallax errors. Then I suddenly discovered the advanced settings on the optimizer-tab, when I checked "Field of view", "a", "b", "c", "Horizontal shift" and "Vertical shift" under "Optimize globally" all of my panoramas got perfect (PTGui says "Too good to be true" when optimizing). Now I wonder if I actually have got the nodal point right or if there still is something wrong with my Nodal Ninja-settings that's getting corrected in the software? I want as much as possible to be optimized with hardware and not by some more or less "inaccurate" software-algorithm. Do you have problems stitching panoramas with PTGui without optimizing the horizontal/vertical shift?
    On the hardware end of things - the settings for your camera/lens @10mm should be 52.5 on the lower rail and 105mm on the upper rail.
    Can you confirm these settings?
  3. Re: Have I found the nodal point? (PTGui shift-question)

    #3

    Quote Originally Posted by Bill Bailey View Post
    On the hardware end of things - the settings for your camera/lens @10mm should be 52.5 on the lower rail and 105mm on the upper rail.
    Can you confirm these settings?
    I have calibrated the lower rail to 53.5 mm and the upper rail to 100 mm (at 10 mm). The lower rail was calibrated using a nearby vertical wall against an edge of a building far away. I have examined the images in Photoshop at 100% and 53.5 mm is more accurate than 52.5 mm on my camera. The upper rail I calibrated by putting a tape on a window nearby and aligning it with the roof of a building far away. Again, 100 mm is more accurate than 105 mm. I guess it can differ a bit both on the lens and the camera house. How does sensor alignment affect those parameters? I guess the center of my sensor is a bit off from the center of the lens. I also guess I still should adjust my Nodal Ninja to the nodal point and not to the center of the sensor?
  4. Re: Have I found the nodal point? (PTGui shift-question)

    #4
    Users Country Flag
    Join Date: Apr 2008
    Location: Hong Kong
    Posts: 2,365

    when doing a calibration using external subjects, make sure you calibrate the upper rail first. Upper rail setting is specific for the lens. you need correct upper rail setting in order to get correct lower rail setting.


    nick



    Fanotec
    We listen. We try harder.
  5. Re: Have I found the nodal point? (PTGui shift-question)

    #5

    Quote Originally Posted by irrbloss View Post
    How does sensor alignment affect those parameters? I guess the center of my sensor is a bit off from the center of the lens.
    The position of the entrance pupil is the thing that is responsible for parallax effects. Correction for the sensor offset is provided in PTGui by the shift parameters d & e, which should be included in the optimization.

    John
  6. Re: Have I found the nodal point? (PTGui shift-question)

    #6

    Hey, you just solved the same problems I had with the Parrallax error. I thought my panoramic head was not compatible with my camera when I read your post: I did what you suggested in PTGUi and, BINGO, no more parrallax errors in my panoramas. I obtained the "Very good" optimiser mark on almost all my panoramas.

    A million thanks !!

    Vince
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