e camera. The film pack adapter will hold a pack
of 12 sheets of film, and accordingly, will permit the taking of 12
pictures. The cut film holder is a unit which holds two sheets of film
utilizing each side of the holder.

It is pointed out that the FBI uses the film pack exclusively in view
of the fact that practically all latent examinations will necessitate
the taking of more than two pictures. Further, the film pack is made
so that it may be loaded into the adapter in the open light. Also, the
films are numbered 1 through 12, which is a valuable feature in that
in maintaining notes concerning the latent examinations it is a simple
matter to note by the number of the negative where the latent
impression was developed and photographed. Should it happen that
during a latent examination all twelve of the films are not used, the
film pack, with the slide in place, is taken into the darkroom and
only those films which have been exposed are removed and developed.
The unexposed films remain in the film pack adapter with the slide in
and may be used later.

As was previously mentioned, the camera has a fixed focus; that is,
the camera will take a legible picture only when the latent print is
at the focal point, or exactly flush with the opening of the camera.
The latent print must not be inside the open end of the camera, nor
must it be beyond; otherwise, the picture will be blurred.

[Illustration: 426. When object being photographed does not cover
camera opening, outside light is excluded with piece of cloth.]

Since the camera has its own light source, any leakage of outside
light will cause overexposure of the film. Consequently, if the
surface of the object bearing the latent print which is to be
photographed is uneven or does not cover the entire front of the
camera opening, it will be necessary to use some opaque material such
as a focusing cloth or heavy dark material to cover the front of the
camera so as to exclude all outside light (fig. 426). If a latent
print on a pane of glass or an automobile window is being
photographed, it will be necessary to back up the latent so that there
will be no light leakage. Material showing a pattern or grain should
not be used for this purpose as any such pattern will photograph in
the background and possibly obliterate the ridges of the latent print.

To insure an equal distribution of the light over the latents being
photographed, the impressions should be centered in the