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Re: [PanoToolsNG] Re: best method to stitch 2 circular FC-E8 fisheye with ptgui ?

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  • michel thoby
    Benjamin, You have been wisely advised by Erik and Willy. Making three or four shots gives a better quality... but the 2-shots solution has some unique
    Message 1 of 5 , May 2, 2008

      You have been wisely advised by Erik and Willy. Making three or four
      shots gives a better quality... but the 2-shots solution has some
      unique advantages!

      Take four images at 90 degrees one from each other (but with the NPP
      set as it would be set for 180 degrees spacing i.e. beta= 90 deg. See
      http://michel.thoby.free.fr/Laseresult.html) and optimize by using
      control points only for subjects that are sufficiently far (>2 m)
      from the camera. Make sure that CP are also requested for at least
      one of the opposite pairs of hemispherical images. After this
      optimization, remove the other two opposite images from the PTGui
      project and keep only the remaining pair. Save the script as a
      template for further use.
      Use the most precise rotator for the two-shots and a mounting
      interface for the camera that is accurately repeatable.

      You may know that this 2-shots technique with a fisheye is under
      these conditions, the only way to guarantee absolute absence of
      parallax errors along the (sole) seam whatever is the distance of the
      subject! And this is why you may use a template with confidence :
      Trying to make a template with a single pair of image only would be
      vain: you need to have control points all over the images to get
      valid correction correction coefficients (a, b, c) and offset
      parameters (d and e).
      Note: I have not yet found why PTGui sometimes randomly finds
      successfully some control points on the overlapping ring on a single
      pair of images. But this is very rare indeed;-)

      My recent experiment have shown that the real useful angle of view of
      the FC-E8 fisheye converter is about 190 degrees and not 183 degrees
      (as it was initially specified for the old CoolPix series) when
      mounted on the recent CP P5100 that has a larger sensor and most
      probably a revised lens design.
      The adapter from Agnos that fits the FC-E8 is too long to yield the
      largest angle of view: the rear of the fisheye converter should
      ideally be much closer to the front of the zoom lens when the latter
      is in "Wide" and "Converter" mode settings.
      I have therefore devised a way to benefit from this untold feature
      and wrote an article where the mechanical data are given for the
      shaving operation of the adapter: http://michel.thoby.free.fr/DuoPix/
      The image is largest in diameter and is also then sharper near the
      bluish blurry ring and the latter is thinner as the vignetting is
      reduced. The TCA is very slightly increased but it still can be well
      and simply corrected.

      I presume that the Nikon UR-E20 adapter is also not adapted (!)
      because being also too long but I am still waiting for delivery from
      Nikon France to make sure;-(

      Best regards,

      Michel Thoby

      Le 2 mai 08 à 15:12, Erik Krause a écrit :

      > > I dont think that Ptgui can stitch 2 FE.
      > It can stitch, but only with manual alignment. It most probably won't
      > find control points automatically. But there is a chance that one can
      > find some manually. There might be a problem blending with such small
      > overlap with enblend, smartblend or PTGui, but there still is the
      > feathering algorithm of PTStitcher and the possibility to output
      > layered PSD and blend manually in photoshop.
      > > Make 3 or 4 shots. You will get a better quality and no seams.
      > Doubtlessly true...

      [Non-text portions of this message have been removed]
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