Unless you own a negative having the same size of the
image you want to get, you need an enlarged negative to make old
process prints. I have never tried the conventional way, that is by
making use of sheet films and an enlarger, so I can only tell you that
a computer is a convenient method to produce contact negatives. The
basic steps are: scanning the negative, using an image manipulating
to create a digital negative of the desired size, and printing out the
image onto a trasparency film.
Here are some links on how to make digital negatives:
- An easy way to get digital negatives by Jim Read
- Two technical papers in the section "Digital
- The author
of the book "Making Digital Negatives for Contact Printing"