Steve, IMHO Jim Jones explained well how to check actual aligment including all variables:
http://www.largeformatphotography.in...=1#post1450198
In fact even we can calculate the shimming nedded in the easel with a single test.
1) Divide the head vertical travel by the number of tours of the head elevation knob.
2) Set optimal focus for the center.
3) From that focus position, see the angle it has to rotate the head elevation know to get perfect focus in each easel corner.
4) Use the factor found in step 1 to know the shimming in each easel corner.
Any laser aid would make the alignment procedure more convenient, but the method explained by Jim delivers perfect results and includes all variables, even it corrects any lensboard tilt with an scheimflug correction. Of course we can also check the lensboard vs film holder alignment, but if there is a minor missmatch in that... then Jim's method also corrects it !!
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