Bruce and Mishka-
According to the lens barrel DOF markings, everything between 3 feet
and infinity should be in focus at f5.6. The DOF at 15mm is
tremendous! Even so, I'm not complaining so much about the left side
of the image, but the right side, where the corner is at about the
same distance as the brick wall but is still quite blurred.
Nevertheless, when daylight returns I'll shoot a larger wall from the
same distance to check this out.
Thanks very much for your interest and comments.
Regards, Jim