Originally Posted by Michael R 1974
CPorter: Regarding the hinge rule, how do you personally estimate the distance J?
I apologize for such a late response, I never saw this question, but I'll try to provide one here..........

I step out from behind the camera and stand to the side and look at the far element and invision the plane of sharp focus to the near element, then continuing toward the camera past the near element, eventually the plane of sharp focus passes through the ground where it will intersect a vertical plane through the lens that is parallel to the film (or more simply just the height of the lens above the sharp plane of focus for the distance "j").

It's a guess as to how many feet below the lens, through the ground, where the plane you want sharp is intersecting the "parallel to film lens plane", which also should be projected through the ground where the two meet at the "hinge". I've never nailed it the first time, but it has gotten me pretty close, then it has to be tweaked from there. One thing to remember is that when tilting the lens, the plane of sharp focus tilts more than the degree of tilt you actually gave the lens itself. So if your're only tilting the lens, say, 3 degrees, then you know that the plane of sharp focus is tilted more than 3 degrees. By how much is not important, just know that is the case.

Howard Bond's "Focus-Check" procedure will get you there just the same, in fact, I have used the calculation to estimate tilt angle, then I have used Bond's procedure to do the tweaking. Sometimes I have just used Bond's focus-check to arrive at the plane I want in focus. It takes some practice, but when you understand it, it becomes second nature.....I would do a lot of practicing around the house/yard before I even put film in the camera.

The last thing I think one should remember is that Merklinger states that DoF is maximized with an untilted lens, because an untilted lens does not present a "cone" shaped DoF region in front of and behind the plane that is sharply focused, narrow end of the cone is closest to the lens. When the lens is tilted, the subject should not have tall elements that are near the camera, they should be much closer to the "far" elements due to the cone shaped DoF. But of course, never using lens tilt in order to maximize DoF, means that you probably are not getting the most out of your LF camera system.