Evening star., 1950-05-28
By Alexander J. Wedderburn
Curator Of Photography
The Smithsonian Institution
(Second of q Series.J

(Second of SeriesJ
Last week we began a discussion
Of slide films, touching on the
advantages of the small trans
parencies to those who have use
for large collections of pictures
We showed how slide films could
be used individually or in sequence
either as records or for story tell
ing. Today we go a step further
and tell something about produc-
ton methods for the amateur who
works in the home laboratory.
Some beginners have SHE'D away
from making slides because they
were hesitant to try a new print
ing medium. Actually there is
little difference between making
prints on film or plates and max
ing them on the familiar photo
graphic printing paper. Slides can
be made either by contact or pro-
lection methods. The same con-
tact printer or enlarger you have
in your darkroom for paper print
ing can be adapted for slide print
ing. Certain cameras can be
equipped with a supplementary
back and extension unit and
mounted on an enlarger stand
assembly and are then used as an
enlarger
Area Is Limited.
An important point to learn
from the first is that the picture
or image which you want to show
on the screen should be centered
properly on the plate or film which
is to be used as the finished slide.
Unlike printing papers, the entire
slide is not used for the final pic
ture. If you are to make ,2x2
slides keep in mind that the
largest useful area of your slide is
about 1x1l u inches, the remaining
margin being covered by the slide
mask. With the larger 3Hx4
slide (Which very few amateurs
have use for), the maximum area
that can be used is 2Ax3 inches.
To avoid guesswork and un-
necessary measuring or mask pre-
pairing simply use the final bind
ing mask over the plate or film as
a guide. With this in place you
can go ahead and compose your
picture and focus with a sheet of
sensitive paper-then substi-
tute the film or plate when you
are ready to make the exposure.
A mask should not be used when
making contact print slides be-
cause the mask would interfere
with a good contact between the
negative and the positive medium
used.
1t is most important, when max
Ing slides by contact, to insure an
absolute contact between the neg
ative and positive materials be-
cause the slight fuzziness caused
by imperfect contact between the
two will be many times empha-
sized when the image is projected
And don't forget that your slide
will be- projected in image to q
much greater size than any of the
prints that you have been ac-
customed to making. To check
your contact machine you can
make a test negative by placing a
sheet Of film and a piece of win
dow screen in contact and expos
ing. Then develop and fix and
you will have a grid negative
When this is placed in contact
with the positive material and ex-
posed as you will your slides, it
shows up on the final print any
lack of sharpness of line from the
edges to the center. Incidentally
the normal contact printer light
should be replaced for slide work
with a 712 watt bulb of the FROST
ed variety.
If you wish to use charts or
graphs or decide to copy typed or
printed material for captions, you
can use many cameras for copying
purposes. Horizontal copying can
be done with the camera on a tri-