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Re: [PanoToolsNG] Samyang 8mm

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  • Ricardo TVB
    My best results using Samyang with 5D MKII is at F/8 and focus set to 0.7m. This is the sharpest image for this combo (at least for my samples) from 30cm to
    Message 1 of 62 , Nov 1, 2010
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      My best results using Samyang with 5D MKII is at F/8 and
      focus set to 0.7m. This is the sharpest image for this combo
      (at least for my samples) from 30cm to infinity.



      Em 01/11/2010 13:03, Roger D. Williams escreveu:
      >
      > On Mon, 01 Nov 2010 22:00:36 +0900, A Kielcz
      > <roblee007@... <mailto:roblee007%40yahoo.com>> wrote:
      >
      > > Thank you Roger.
      > > It was shot in RAW at 5.6 and focus was set to 1.5m.. I
      > could not u/l
      > > original NEF, because it wouldn't accept it.
      > > Is it possible that CA wasn't even on both sides,
      > because it wasn't
      > > level?
      > > Tests are good, but I want be able to correct anything
      > anyway.
      >
      > You're welcome. Hmmm. Looks a bit soft for F/5.6. Try it
      > at F/8 and 11
      > and see if you get noticeable improvements. Also try 2.0m
      > or even 3.0m.
      > As I said, I had to focus further out than dictated by the
      > hyperfocal
      > rule in order to get the best sharpness from my Peleng.
      >
      > If CA is not the same on both sides the cause will be in
      > the internal
      > geometry of the lens, not any orientation of the camera. I
      > suggested
      > "decentering" which simply means that the optical axis of
      > the lens
      > isn't precisely aligned with the lens barrel. But the
      > effect is very
      > slight, so I wouldn't worry about it.
      >
      > You must have used a RAW file processor to get your JPEGs,
      > and it
      > can introduce softness in the resulting images. The RAW
      > processor is
      > where you should remove the CA. CA looks bad and seems
      > serious, and
      > if left uncorrected plays havoc with control point
      > location (think
      > about having fringes on the opposite sides of the same
      > feature when
      > it appears on the extreme left of one shot and the extreme
      > right of
      > the next, overlapping, shot! You don't want that. All RAW
      > processors
      > I've played with have sliders to eliminate CA. Play with
      > them until
      > you can't see coloured fringes at full x1 screen
      > magnification!
      >
      > Roger W.
      >
      > --
      > Business: www.adex-japan.com
      > Pleasure: www.usefilm.com/member/roger
      >
      >


      [Non-text portions of this message have been removed]
    • Michel Thoby
      ... Mark, thank you very much for sharing this link. I had found by myself the same way to mechanically set the focus scale ring at the correct position. I can
      Message 62 of 62 , Feb 10
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        Le 9 févr. 2014 à 23:22, <markdfink@...> <markdfink@...> a écrit :

        Absolutely don't trust the focus scales on any of their lenses! I found out the hard way with a 35mm that I rented, and see that both my 14mm and 8mm have the same issues. I used this link to find out how to fix it so that I can reliably use hyperfocal settings when shooting.


        Mark
        Mark, thank you very much for sharing this link. 
        I had found by myself the same way to mechanically set the focus scale ring at the correct position. I can confirm that it made me a happy user of the Samyang 14 mm for more than three years now. 
        I was inspired by Jeffrey R. Charles who had kindly taught us in 2009 how to solve the problem that similarly affects the Samyang 8 mm f3.5 fisheye lens. It is a simpler fix than for the rectilinear WA though:

        Best regards, 

        Michel Thoby
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