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Re: NP 200 and 300mm Canon

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  • Erik Krause
    ... I thought so, too. But then I thought closer and considered hyperfocal distance and desired resolution. I calculated the expected parallax error and it s
    Message 1 of 32 , Feb 2, 2009
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      Matthew Rogers wrote:

      > You'd be hard pressed to find ANY shooting scenario where you need to
      > have a 200 or 300mm lens rotate around the nodal point.

      I thought so, too. But then I thought closer and considered hyperfocal
      distance and desired resolution. I calculated the expected parallax
      error and it's not so small: A 200mm in portrait has 6.5° FoV. Given 25%
      overlap you rotate 4.9°. If you shoot at f/16 with hyperfocal distance
      you get a near limit of about 50m.

      Now if you assume a displacement of 200mm (rotating around the front
      lens instead of NPP) and use the formula from
      http://wiki.panotools.org/Parallax you get a ß of 0.01°. Since the total
      parallax error is twice as large (0.02°) this is roughly 1/320 of the
      total portrait FoV.

      This gives about 8 pixels parallax on a Nikon D3 or 11 pixels on a EOS
      5D II. Quite reasonable if you go for a gigapixel panorama. And the
      overlap in vertical direction (or landscape) is by 1.5 larger.

      Ok, the estimated seam line will be in the middle of the overlap, hence
      the values most likely will be 25% smaller: (6 resp. 8 pixels in
      portrait or 9 resp. 13 pixels in landscape)

      --
      Erik Krause
      http://www.erik-krause.de
    • bigwade
      Hey, Hey.. reshoot of course.. with a very wrong NNP it can be an issue at 2 meters. ... -- View this message in context:
      Message 32 of 32 , Feb 2, 2009
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        Hey, Hey..
        reshoot of course..
        with a very wrong NNP it can be an issue at 2 meters.


        Matthew Rogers-2 wrote:
        >
        > So you want to combine the shots taken at 100mm with the new ones
        > taken at 200mm ? Or do you simply want to reshoot the entire image at
        > 200mm. Either way I still dont see where the parallax issues can occur ?
        >
        >
        >
        > Matt
        >
        > On 2 Feb 2009, at 23:38, bigwade wrote:
        >
        >>
        >> Maybe I'm not clear enough.
        >> First I want to shoot a landscape shot with client in the studio.
        >> Lighting and settings are oké.
        >> Let's say at 100mm.
        >> But the client wants higher resolution.
        >> So I rotate the camera to portrait, zoom in to 200 and make more
        >> shots.
        >> (even with different focussettings to combine in Helicon or whatever)
        >> Parallax will be an issue unless you have big overlap and a lot of
        >> shots.
        >> (BTW the beer will be dead by then.:-)
        >>
        >
        >
        >
        >

        --
        View this message in context: http://www.nabble.com/NP-200-and-300mm-Canon-tp21647383p21801493.html
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