Nick-Lens Ring for Canon 8-15mm f/4L Fisheye?

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Thread: Nick-Lens Ring for Canon 8-15mm f/4L Fisheye?

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  1. #46
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    Join Date: Apr 2008
    Location: Hong Kong
    Posts: 2,387

    Quote Originally Posted by gomi View Post
    Due to the USM drive markings don't help at all. The 5D (without II) does not support live view. Even if it would I would never rely on that. The final picture is out-of-focus if you turn the focus ring by about half a milimeter. That's why it is sooooo important to visually check the distance setting. Even to auto-focus an object in the far distance sets the wrong distance. I work with this lens for almost 5 weeks and see no way to overcome a hidden distance window.

    Michael
    I will work out a tutorial on how to rebuild the distance scale on other part of lens.

    Nick



    Fanotec
    We listen. We try harder.
  2. #47
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    Join Date: Apr 2008
    Location: Hong Kong
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    Quote Originally Posted by nick fan View Post
    I will work out a tutorial on how to rebuild the distance scale on other part of lens.

    Nick
    Just found that Michel offered the trick to adjust the focus with a hiden focus window in his review.

    http://michel.thoby.free.fr/Canon_8-...yperfocalpoint

    6) Tip: If, for any reasons, the Autofocus temporary solution -read item #3 hereabove- is not reliable, then viewing the scale of distance of focus (visible through the plastic transparent window) is essential to manually set the lens correctly and thus to get sharp-focused images. If for any reason, it is not visible (for instance if it's hidden inside a clamp ring), one has then to use a workaround to set the lens to the hyperfocal...

    One simple way is 1) to push the setting ring manually so that it is mechanically end-stopped at {position >> ∞}and even farther so as to surely overshoot this position (the ring can be moved freely because the de-clutching effect of the USM), then 2) to reverse the rotation from this extreme end positon back to a final known position with respect to visible marks on the barrel. In other words, this final position is attained after rotation of a known fixed distance (i.e. 8.2 mm) from end-stopped state of the ring in order to set exactly the lens at the hyperfocal {H}.

    As a matter of fact, this process is simulating a virtual "twin" distance-scale that replaces the obstructed original one. And this "new scale" is made available on another part of the lens barrel: in this effect, I have painted in white with a "white pencil" one groove on the rubber ring (rapid correction TippEx liquid may work equally). After having rotated the ring toovershoot beyond the infinity end stop action (position on the -invisible- scale at the Infinity compensation mark { >> ∞}), I move it back to the left edge of the letter "Z" of the word "ZOOM" and not more; (note that this has yet not changed th actual setting on the hidden scale itself). Then I reverse (again) the rotation and move the white groove to the right edge of the letter "M" of the same ZOOM word. The distance of focus indicator is now at this stage exactly aligned on the right edge of the "1" meter position on the scale and hyperfocal is set.

    Remarks: the word "ZOOM"(see image above) is engraved on the front fixed part of the barrel. Any other adequate pair of points of reference on the body (e.g. two marks applied on the red thin ring) could be used as long as they are separated by ~8.2 mm. BTW there is a 5:2 ratio between the rotation of the ring and the synchronized distance scale and that de-facto magnification soothes in a way the difficulty to set accurately the hyperfocal. Voila!



    Fanotec
    We listen. We try harder.
  3. #48

    As you see Michael also found out that setting the focus distance is really tricky with this lens. His "solution" is quite obvious and I also thought about that kind of work-around. I am not very confident that I'll like the "solution". Right now I'm looking for a company that is able to machine a window into the lens ring to see the distance window.
    Michael
  4. #49

    Could anybody tell me the NPP setting for the Canon 8-15 on an R10 @ 7.5° up 4 shots @ 12.5mm.
    On the M1 that I tested with the Canon 8-15 on an 5D MII I had the following setting:
    Lower rail 169mm
    Upper rail 110.5mm @ 7.5° up.
    The point is at the front edge of the lens hood mount.
    See this > http://michel.thoby.free.fr/Canon_8-...oParallaxPoint
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