no parallax point - ultimate M1-L

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  1. no parallax point - ultimate M1-L

    #1

    I am trying to find the no parallax point for a nikkor 16mm fisheye on a Nikon D800 using a ultimate M1-L with RD16 rotator and a U3 camera plate (I actually founded it).

    When the lower rail is adjusted so that the rotator screw is aligned to the horizontal axis of the finder/viewfinder, the actual center of the image is shifted to the left (as it looks in the photo - the red point is the center of the image) and this can not be adjusted.Click image for larger version

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    I know that this is compensated when setting the upper rail for shooting single row panoramas but having this offset doesn't influence when shooting zenith, nadir or multi-raw panoramas?

    Sabin
  2. #2

    Sabin, The centre screw will not necessarily be positioned at the exact centre of the image frame when the panorama head is properly set up. There is usually a small offset of the optical axis of the lens with respect to the camera's image sensor. Given that the entrance pupil of the fisheye lens is not located at a single point for light rays entering the lens from different angles, the panohead setup is in any case necessarily a compromise as parallax cannot be perfectly eliminated over the entire image frame. Set up the head as best you can and try shooting a couple of panoramas. These tutorials should help:
    .
    http://www.johnhpanos.com/epcalib.htm
    http://www.easypano.com/forum/displa...1&TopicID=4162
    .
    In the case if the second of these tutorials, you may find it helpful to temporarily mount a CD/DVD below the rotator foruse in checking the lateral position of the camera.
    .
    John
  3. #3
    Users Country Flag
    Join Date: Aug 2008
    Location: Netherlands
    Posts: 1,734

    Hi,

    try 135.5 for LRS = lower rail setting and for 16mm URS = Upper rail setting 119mm.

    This was found by Baltimore Bob some time ago.

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    I use a hard paper circle below rotator. You can use it as sample and glue it onto a postcard for example. 10 cm diameter and a 8mm or 3/8" hole in center placed on top of tripod before mounting the rotator.

    Workflow for Smooth Test: use the presets of Bob. Set aperture to f/22. Pitch down till you see the corner of the card at the bottom in the viewfinder. Set focus to the corner.

    Now take your shots around. Import to PTGui Pro. Align, go > advanced, > optimizer, use heavy and lens shift and optimize. top tab > del worst control points.

    Check panorama settings and set them to 360 x 180. create panorama as .mov file.

    Open mov, move down to Nadir and check the circle. Tooth cuts to the right, move to the right 1mm, tooth cuts to the left, move to the left 1mm. Final check would be a set of three: 50 cuts to the right, 51 is ok, 52 cuts to the left. Examples of D7000 are added.

    This is the best method to compensate sensor misplacements and differences in lens production to find your lower rail setting.

    Have a look to Nikon Rumors as well concerning "bad focus" of D800. May be you should have it checked at Nikon Service Point.

    http://nikonrumors.com/2012/07/17/co...ng-issue.aspx/

    @Vincen: what's your LRS? Cheers.

    Heinz
    Last edited by hindenhaag; 08-20-2012 at 07:25 AM.
  4. #4

    Thank you for replying.
    I will calibrate the panohead according to your tips.

    Sabin
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