The
quality of your enlarging lens
will lead to better and sharper results at greater magnification. The aperture
( low number = large opening, high number = small opening) you set not only
affects the amount of light it lets through but the depth of field as well. A
good average aperture is F/5.6 in most cases. If the exposure times are to
short a larger F number is needed, this will give you a chance to hold back
shadow areas that may become to dark to show any detail. But don't get carried
away and close down the lens by too many
F numbers as this may over heat the negative causing it to buckle, making the
picture loose sharpness.