How do asymmetrical movements work?

I am going to take on a longer-term project of building an 8x10 camera and I have become curious about asymmetrical movements. I cannot figure out how they work, and I have yet to find a good explanation of them. As far as I can tell, on the Sinar X and P2 it seems that the swing axis is set off to the side of the standard. In my mind, in the world of tilts this would be similar to base tilt, but I believe that I am mistaken in that regard. Does anyone know of a good explanation of how this works?

- Justin

It's not exactly like a base tilt, because the tilt or swing axis actually runs through the groundglass, rather than being below the groundglass.

So the idea is that you can focus on the subject at the tilt axis, marked by a dotted line on the groundglass in the case of Sinar, then tilt around that axis, and the area at the axis stays in focus. With the Sinar you would normally to this on the rear standard, and then if you wanted the tilt to be in the front standard to avoid distortion, you would read the tilt angle off the rear standard, zero the rear standard, and tilt the front standard by the corresponding angle.

The Linhof Master GTL lets you move the tilt and swing axes. With the Sinar, if the tilt or swing axis doesn't happen to intersect the desired plane of focus, you would use rise, fall or shift to put the tilt or swing axis in a more convenient place, measure the tilt or swing angle as described above, and then recompose using rise/fall/shift. The Linhof's continuously variable asymmetric tilts and swings makes this recomposition step unnecessary.

You did half of the explanation yourself. Now mark the swing and tilt axis on the ground glass, focus an object in the desired plane of sharpness along that line, lock focus and swing or tilt appropriately to get the other objects in focus. Only useful for subjects that needn't be shown rectilinear.

So, if I am getting this right, center tilt would be the same as if the Linhof tilt was set in the center of the standard, and tilting the standard would adjust the angle of the plane of focus, but that horizontal line area across the center would always be in focus? (Assuming one had focused there in the first place)


Edit: I did a quick sketch of a possible mechanism for variable asymmetric swing. The blue square with gray inside would be the rear standard with groundglass, and the green is a rail attached to the standard which would control swing. The red is a hinge or other "turnable thing" with a screw top, and the pink line is the axis of swing. So, Everything along the pink line on the groundglass will remain in focus, no matter how weird the swing, and when the screw top on the rail is loosened the groundglass and rear standard can be moved side to side, moving the swing axis, then tightened and the swing adjusted as desired. Would this be basically correct?

Justin, here is the link to Ebony's .pdf document explaining asymetrical view camera movements.

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