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  1. #41
    chuck94022's Avatar
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    Quote Originally Posted by CPorter View Post
    Bond is claiming that a tilted plane of sharp focus (refer to as the focus plane) moves parallel to itself, not the focal plane. The focal plane is a line parallel to the lens plane but one focal length in front of the lens------so, to obey the H-Rule, the focal plane, the focus plane, and the parallel-to-film lens plane must converge at the H-line. Taking part of your suggestion, as I draw a line parallel to the focus plane, it continues to intersect the S-line and the parallel-to-film lens plane, but comes off the focal plane line, giving the appearance that an adjustment of the tilt angle is needed to re-establish the H-Line.

    By this, then, it appears to me that, while the S-Rule is being obeyed with parallel movement of the focus plane , the H-Rule is not. Merklinger says that is possible, but the camera will not be in focus until both the S-Rule and the H-Rule are obeyed simultaneously. When re-reading Bond's statement, he is either:

    - wrong, as you say
    - he is right but fails to convey it properly in the article
    - he is right, but I have totally misinterpreted his statement

    I have to assume that when he says "....a tilted plane of focus moves parallel to itself....when the focus knob is turned...." that he means the front standard. Because, moving the back standard "rotates" the focus plane at the H-Line, and I view a rotation movement as different from a parallel movement.
    For what it is worth, when I wrote "focal plane" above I meant "plane of sharpest focus". My bad for trying to save some typing.

    The bottom line though as can be seen by the figure is that the light doesn't know whether it is the front or read standard that moves. Both movements accomplish the same optical result, of change the distance between lens and film, as shown. I think it is plain to see that the same figure represents the result of either a front forward movement or a back rearward movement.

  2. #42
    CPorter's Avatar
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    Quote Originally Posted by chuck94022 View Post
    For what it is worth, when I wrote "focal plane" above I meant "plane of sharpest focus". My bad for trying to save some typing.

    The bottom line though as can be seen by the figure is that the light doesn't know whether it is the front or read standard that moves. Both movements accomplish the same optical result, of change the distance between lens and film, as shown. I think it is plain to see that the same figure represents the result of either a front forward movement or a back rearward movement.
    I have come to that conclusion, thanks. I also believe that Bond is saying the same thing, but I've just interpreted his words entirely wrong, that's my opinion on it anyway.

    Nevertheless, been practicing some more with finding the proper tilt angle, using Merklinger's simple equation for tilt angles less than 15 degrees [angle = focal length / (5 x j)], and it just works like a charm, it puts the angle so very close, it may need just a little tweaking. I had trouble at first deciding how to determine how much of the distance "j" may lie below the ground to intersect the H-line. Simply, I stepped outside the cloth and just envisioned it, plugged in the number and set the angle of the lens plane, I found that each time it needed only the slightest tweaking. This is going to make using my LF camera so much more enjoyable, it had not been fun for a long time due to focusing problems---I believe the proverbial light came on over the head.

    Thanks for your help.

    Chuck

  3. #43
    tih
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    Quote Originally Posted by CPorter
    This is going to make using my LF camera so much more enjoyable
    And that's the important thing!

    -tih

  4. #44
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    Knowing the theory and math of a view camera is a good thing, but
    in the field practical knowledge helps me out more.

    I learned to focus the view camera in a practical way just by viewing this
    video. It is in the video section I think of apug but here is a link anyway :

    http://www.youtube.com/watch?v=gR4m70xr9mE

  5. #45
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    Quote Originally Posted by henk@apug View Post
    Knowing the theory and math of a view camera is a good thing, but
    in the field practical knowledge helps me out more.

    I learned to focus the view camera in a practical way just by viewing this
    video. It is in the video section I think of apug but here is a link anyway :

    http://www.youtube.com/watch?v=gR4m70xr9mE
    Yes, I've seen this video-----it's a demonstration of Bond's "Focus/Check" procedure that I referrenced earlier in this thread. In his example, the planes requiring sharp focus for both the tilt and swing are established by the box itself, so putting them in focus is relatively easy compared to when the best plane(s) of focus have to be found, at least that's my experience so far. My understanding of the Hinge Rule, though, has greatly facilitated the "Focus/Check" procedure.

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