Vaughn's point here is right on. It's really important to mentally determine the where you want the plane of sharp focus to be; only then can you really decide what movements you need.
So, if the plane you want to focus on is not parallel to the back, but displaced top-to-bottom (e.g., like a near/far landscape of flat ground), you need tilts. If the plane you want to focus on is displaced right-to-left (e.g., a wall is close on one side and stretches into the distance), you need swings. If the displacement is oblique, you'll need both swing and tilt.
Once I've determined where I want the plane of sharp focus to be, I choose focus points: top and bottom of the ground glass for scenario 1, right and left of the ground glass for scenario 2 and both top/bottom and right/left for scenario 3.
Before applying tilts or swings remember the old adage: "The back backs away from; the lens looks at" the plane you want to have in focus. Now, unless you have asymmetrical tilts/swings, my procedure would be:
For top/bottom points, I always focus first at the bottom of the ground glass (usually the more distant point) since I use field cameras with base tilts a lot. With axis tilts it doesn't matter. Anyway, I focus on the first focus point then tilt lens stage or camera back in the proper direction (i.e., "backing" or "looking") till both my chosen points are equally out of focus. Then refocus on the first point and then focus on the second point. If you have to rack out the bellows to get point 2 in focus, you need to move back or lens stage in whatever direction is needed to make the bellows a bit shorter. Vice-versa if you have to shorten bellows extension to get point 2 in focus. A couple iterations of this and you'll have both your points in focus.
The above works for left/right focus points too, just substitute "left/right" for "top/bottom."
For an oblique plane of sharp focus, you'll have to make adjustments for both top/bottom and left/right. It doesn't matter which you start with, however your focus points need to be directly opposite each other on the ground glass (i.e., vertically and horizontally aligned for top/bottom and right/left respectively). Apply one movement (say tilt), then apply the second (swing) using the method above. Then go back and check.
It's really easier and faster to do than to explain.
The next step for me is finding the focus spread between the nearest and farthest objects I want in focus in the scene (like Mark points out, there are always pesky objects that don't lie in your chosen plane
). If you've applied tilts/swings you need to really remember that the "near" is not necessarily what is nearest to you and the camera, but what is in front and/or above the plane of sharp focus and the "far" is what is behind and/or below the plane of sharp focus. I find the focus spread and note the bellows extension for each extreme. I then position focus exactly halfway between the two extremes and use the total distance to find the optimum f-stop to keep everything acceptably sharp (as described in the article on the LF home page, "choosing the optimum f-stop").
Hope this helps,
Doremus
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