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  1. #11
    KJK
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    Tom

    my sentiments exactly. I have owned and used a Sinar 8 x 10 F2 camera in the past. It had base tilts, WHICH ARE NOT the same as ASYMETRIC tilts. What I am getting at here is that I would like to incorporate some sort of Asymetric tilt into a field camera (without having to resort to buying a an Ebony) and all I want to know is whether there is a mathematical formula for what the circle of tilt has to be (i.e how far forward the top has to go and how far back the bottom has to go, and how far off the film plane it has to be in order to use basically the same sort of set up as sinar does (i.e focus on the 1/3 line, tilt the front, transfer to the back, and your done)

    Dan

    The advantage is the speed in which you can work becasue you are not having to constantly refocus everytime you tilt or swing the camera.

  2. #12

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    Quote Originally Posted by KJK View Post
    Tom

    Dan

    The advantage is the speed in which you can work becasue you are not having to constantly refocus everytime you tilt or swing the camera.
    I thought that what axis tilts were for?

  3. #13
    AgX
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    Quote Originally Posted by KJK View Post
    ...all I want to know is whether there is a mathematical formula for what the circle of tilt has to be...
    Rodenstock once offered a calculating disc on this, solving some of your problems.

  4. #14

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    You might try emailing Leonard Evens. He's a Professor Emeritus in mathematics at Northwestern University. He's a large format photographer, and I've seen him take part in these types of discussions.

  5. #15
    KJK
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    Quote Originally Posted by dslater View Post
    I thought that what axis tilts were for?
    No. With axis tilt you are also constantly refocusing because as you tilt for either the far or the near the other side of it goes out of focus. So now you have to refocus and then redetermine whether your tilt or swing is correct. If its not then you have to retilt or reswing, and then refocus again. Many many moons ago when I was at Brooks Institute we spent a whole semester learning how to refocus after swinging or tilting!!!!

  6. #16
    Ole
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    With the sharp focus at the tilt axis you won't have to refocus regardless of where the tilt axis is - presuming your tilt axis also passes through the front (?) node of the lens. The only camera I know of where the tilt axis is repositionable with regards to the lens is the Carbon Infinity, and I can assure you that if everything is set up correctly there is no refocussing after swing or tilt. Then shift and rise can be applied after the swing/tilt/focus!
    -- Ole Tjugen, Luddite Elitist
    Norway

  7. #17
    KJK
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    Look, you have two axis. horizontal and verticle. and you have three methods of swinging and tilting. you have base, you have center, and you have asymmetric. with base and center swing you have to refocus after tilting, then adjust, then refocus etc. You definitely do with center swing (i.e. on the lens axis or nodal point) becuase when you tilt you change the position of the image circle thereby resulting in unsharpness.

  8. #18
    Ole
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    Quote Originally Posted by KJK View Post
    ... with base and center swing you have to refocus after tilting, then adjust, then refocus etc. You definitely do with center swing (i.e. on the lens axis or nodal point) becuase when you tilt you change the position of the image circle thereby resulting in unsharpness.
    No. You change the position of the image circle with all three versions, there is no "magic" difference between center and asymmetric tilt.

    If changing the position of the image circle mattered, you would have to refocus after shift and rise too, which you definitely don't (assuming a lens with a fairly flat field).
    -- Ole Tjugen, Luddite Elitist
    Norway

  9. #19

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    I think we need to be clear about something here - are we talking about front tilts/swings or rear tilts/swings? From the talk about the lens nodal point, I assume we're talking about front tilts/swings correct?

  10. #20
    Ole
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    Most of the time, I've been discussing front movements. The rest of the time it makes no difference which end you swing.
    -- Ole Tjugen, Luddite Elitist
    Norway

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