is going to get a bit technical, so
bear with me! This is the ratio between the print and the negative. It is
calculated using the linear rule. To make things easy, lets say we are going to
enlarge a thirty-five mm negative (24 x 36 mm) by a factor of ten this will
give us a print size of 240 x 360 millimeters ( about 9" x 14") in
is related to the distance the negative is from the enlarging lens and the lens
from the baseboard. So as the latter distance increases the former decreases.
In other words the higher the enlarging head is from the baseboard the closer
the lens gets to the negative when it is being focused and vice versa. It
stands to reason that the larger the print the longer the exposure time will
need to be. There will also need to be a change in paper grade to a harder one
as there is a softening in the contrast.