Oh, in the light of morning, rather than the middle of the night when I posted above, it occurs to me that my technique was perhaps a little different. I took the same exact shots from a tripod with only the focus changed. I layered one shot over the other (let's say the near-field on top of the far field) and made the unison adjustments. Then I created a horizontal crooked selection and completed the selection around the sides and top edges. It may be necessary, at this point, to add to the selection with the non-magnetic polygon selection tool to catch any places where the straight edges aren't straight. Finally, I just cleared the far-field area from the near field shot and merged the layers. If this was obvious I apolgize for belaboring the point, but I would rather err on the side of clarity.