Since
film is always copied or contact printed emulsion to
emulsion, the image flops its orientation much in the
same way as things reverse in a mirror. This orientation
is defined as A-wind and B-wind. A-wind film reads through
the emulsion - not the base. This is because the film
has been flipped over when the emulsions of both films
are put in direct contact while contact printed, so
the images are flopped. The copy made from this A-wind
will be a B-wind. Printing alternates the winding of
a film, wound emulsion in or emulsion out. The copy
that is distributed to the theater is normally an A-wind
because the base of a print always faces the lens of
a projector (camera and projector winds are usually
opposite). A&B winding usually comes up when printing,
duplicating, editing film manually and negative cutting.
