Nikon PC NIKKOR 35mm f-2.8 - Manual (Page 32)

When making enlargements, be sure
that the negative is absolutely parallel
to the easel to prevent distortions.
All of the focusing adjustments on
the enlarger should be maintained
constant from one exposure to the
next. When the prints are removed
from the washer, insert them in a
rotary dryer facing the same direction.
O verlapped area for vertical shifting