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  1. #11

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    Yesterday, I posted two images in the critique gallery for which I used the scheimpflug technique. They are Scenic By-way #1 and #2.

    I recommend that you start with a flat suface like a table top or road and practice getting it sharp and then move on to three demensional objects. With front tilt, you lay the plane of focus down toward the horizontal, and you have to use a smaller f-stop to bring three-d objects into focus. Try getting the table top in focus first.

    Allen

  2. #12

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    Thanks guys, this is what I wanted!!!

    great, kind regards

  3. #13

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    Soeren,
    Without being critical, might I ask if you're familiar with how the Sinar tilt/DOF calculator system works? On most (all?) Sinar cameras, there is a tilt calculator built in, which gets you there quickly, as well as a reasonably accurate (though I tend to stop down an additonal stop) DOF calculator.

  4. #14

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    The way I usually deal with scheimpflug in practice is as follows. When you have your first object (or point) in focus, the relative position on the ground glass of a second object that you want in focus, combined with the direction you have to focus to get it in focus ("out" or "in", if focusing with the front standard) tells you what kind of movement to apply.

    For this example, remember that the ground glass is an upside down and backwards representation, but when I say "top" I mean the actual top of your ground glass and when I say "right" I mean the actual right side of your glass - not the position of those objects in the real world beyond the camera.

    So, for example, on the ground glass you've got an object on the left that is in focus, and an object on the right that is not in focus. To get the object on the right focused, you have to focus the front standard out (increase extension) because in this example that object is closer to you. You can use that information to say "okay, move the right side of the front lensboard "out"" (because the right-most object required a focus adjustment "out"). This is just a mental shortcut that happens to fit how the movements work out (that "right most" object on your GG is actually to the left in reality, and since it is closer to you moving the right side of the lens board "out" is the correct movement).

    If I have an object on the bottom that is in focus, and an object on the top that is out of focus but that can be brought into focus by focusing the front standard "back" (decreasing extension), then I tilt the top of the lens board back. Note that the inverse relationship works just as well; in the same scenario I could say that to get the bottom object in focus I have to focus "out", and therefore I have to tilt the bottom of the lens board out. This is the same movement as tilting the front back (because that puts the bottom of the lens board relatively "out").

    In this way you can focus on one important object in your focus plane, switch your attention to the other object and adjust focus for it (while noting which way you focus), and then use this principle to apply a slight tilt or swing. Test it again and see which way you need to move, and with a few iterations you can get it perfect.

    This isn't really the technically correct way to look at the scheimpflug principle optically, but it's a shortcut that always works.
    Last edited by walter23; 11-11-2007 at 02:32 AM. Click to view previous post history.
    The universe is a haunted house. -Coil
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  5. #15
    Bruce Osgood's Avatar
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    What I know of the Scheimpflug Principle is that when you work hard enough to focus everything by eye and it works, you have proven the Scheimpflug Principle.

  6. #16
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    Something that I have learned since my entry into LF and dealing with lens tilt is that the plane of focus tilts more than the tilt given to the lens and so it can be easy to apply too much tilt. I have been quite frustrated at times by providing too much tilt and then having to go back and forth with it more than it seems I should.

  7. #17

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    Chuck,

    Exactly right, in theory, it tilts at double the rate of the lens tilt. Ole has made mention of Merklinger's work, you should read it, quite fascinating stuff. It can help you get your head around some of the more arcane and not so obvious parts.


    erie

  8. #18

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    Quote Originally Posted by epatsellis View Post
    Soeren,
    Without being critical, might I ask if you're familiar with how the Sinar tilt/DOF calculator system works? On most (all?) Sinar cameras, there is a tilt calculator built in, which gets you there quickly, as well as a reasonably accurate (though I tend to stop down an additonal stop) DOF calculator.
    Nothing wrong with being critical. No I don't know how it works or what it is or how to get it But since Im a beginner Im open for suggestions and good advice.
    Kind regards
    Søren
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  9. #19
    Steve Smith's Avatar
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    When researching Shheimpflug, also look up 'The Hinge rule'.

    The two need to be applied together: http://www.trenholm.org/hmmerk/HMbooks4.html

    The Sheimpflug rule on its own only gives one point which the plane of focus passes through making its angle ambiguous. the Hinge rule gives a second point. A straight line through both of these points is the focus plane.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

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