This would be topped with a sheet of glass, weighted a bit to force the negative
surface to contact the paper emulsion. Typically we use the enlarger as a light source.
The head is cranked up to put the lens about 27 inches above the glass. Using the
enlarger, the lens aperture can be used to adjust intensity and the enlarger timer
used for controlled exposure time. In addition, filters can be placed in the normal
enlarger slot to adjust the contrast when printing on variable contrast paper.