DIY

A Homemade Photo Enlarger

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Materials and equipment for a photo enlarger include aluminum foil, plate glass, a cable release, a 35mm camera, a tripod, a cardboard box, a light bulb, and a light fixture with cord.
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The "innards" of the enlarger box before it is sealed. The square hole at the bottom of the carton allows the light to pass out of the box and through the glass, negative, and lens ... and then project the image.
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Diagram of the homemade photo enlarger.
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The author directly under the lens, at the point where the negative's image will appear. The camera — with the enlarger set on top — is attached to a tripod and placed face down. Note the cable release attached to the camera's top.

Not long ago, a friend (and fellow photo hobbyist) told me,
with no little pride, that he’d designed and built a
low-cost homemade photo enlarger. I congratulated him on his
ingenuity but — I confess — assumed that the
device was likely an interesting plaything rather than a
practical piece of photographic equipment. Therefore, when
it came time for me to have an enlarger, I
promptly made the rounds of my area’s photo supply stores
to see what such establishments had to offer.

It soon became clear that I’d have to do one heck of an
enlarging job on my budget before I’d be able to
purchase one of the expensive pieces of equipment. I was,
as the saying goes, between a rock and a hard place. So
(extremely grateful that I’d kept my doubts about his
creation to myself) I called my picture-taking buddy and
asked him to tell me how he’d built his enlarger.

Well, to make a long story short, I wound up assembling
five of the devices before I felt I’d really
developed the design to its full potential. The fifth
enlarger, though, worked like a charm … and as an added
bonus, I believe I learned enough in the course of putting
my rejects together to tell you how to produce a
“perfect” blow-up-maker on your first attempt!

Here We Go

Before you begin work on your homemade enlarger, gather the
necessary components: your 35mm
camera and a tripod (most such cameras come equipped with a
50mm lens, which will allow you to make 8″ X 10″ and larger
prints … a “macro”, or close-up, lens will give you the
capability of making smaller prints, as well), a box of
aluminum foil, a scrap of plate glass, a cable release, a
corrugated cardboard box of about 4 1/2″ X 4 1/2″ X 10″, a
roll of gray duct tape, an enlarging bulb (you can buy one
at almost any photo shop), and a translucent plastic milk
carton (a piece of which will be built into the enlarger as
a filter, to prevent “hot spots” from marring your photos).

Now, mount your camera on the tripod. with the lens facing
down, open the imagemaker’s back, and set one small end of
the box on the opening. (This will enable, you to see how
well the box will “mesh” with the tripod/camera assembly
and to make modifications if necessary. For example, I had
to trim the carton a bit to accommodate some inconvenient
protrusions on my tripod!) When the components have been
“custom fit” to one another, remove the box and — on
the end that will rest upon the camera — cut out a
centered 1 1/2″ X 2″ rectangle. (The light will pass
through the hole and through the negative, projecting
— by way of the camera’s lens — the enlarged
image on your photo paper.) On the opposite side of the
container, trace and cut out a hole large enough for the
socket of your light fixture (roughly 1 1/2″ in diameter).

Once the openings are made, you can line the interior of
the box with aluminum foil (dull side out), taping the
reflective material securely in place. Then put the light
fixture in position and screw the enlarging bulb into the
socket from the inside of the box.

Before sealing the container for good (it won’t be opened
till the light burns out!), cut a 4 1/2″ X 6″ rectangle
from the plastic milk carton and — by making slits in
opposite sides of the box, slipping the plastic through
them, and holding it taut with tape — install the
homemade filter about halfway between the lowermost part of
the light bulb and the bottom of the box. With that done,
you have only to seal the container and cover its
outside with taped-on foil (shiny side out
) … before your homemade enlarger will be ready to go to
work!

Let’s Do It!

In order to use your new piece of equipment, you’ll have to
make sure that the shutter of your camera stays
open . (On many 35mm cameras, the shutter
can’t be held open without using a cable release
that can be locked — or taped down — to fasten
the shutter in its light-admitting position.)

With the camera mounted on its tripod, set your negative
strip on the open back and cover it with the scrap of plate
glass. Then put the enlarger in place, being sure that it
sits upright on the camera. I usually begin (after, of
course, assembling my standard dark room equipment
including trays, chemicals, a “safe” light, and print
paper) by cutting a sheet of paper into test strips …
and then setting the camera’s f-stop at f-8 and exposing
the “trial” bits of paper for ever longer periods of time,
increasing the amount of light by about four seconds with
each strip.

Once I’ve determined the optimum exposure time, I place a
full sheet of paper in position and turn on the light for
just the proper period to give me the best enlargement
possible (of course, the “perfect” exposure time
will vary from one negative, and one type of
paper, to another). My enlarger has a switch built into the
light cord, which allows me to turn the bulb on and off
when I please … although you could, of course, simply
unplug the cord to accomplish the same thing, provided
you’re careful not to move or bump the enlarger in the
process.

Fine Tuning

It’s sometimes possible to improve the quality of the print
by varying your camera’s f-stop: By adjusting the device to
a lower f-setting, you’ll admit more light and thus
effectively reduce the time of exposure that’s necessary.
(The latter option can be quite valuable, as some papers do
not respond well to long exposure times. On the other hand,
though, most cameras operate at their best at a given
f-stop … and — since this “prime setting” is
commonly around f-8 — that’s how I routinely set my
camera.)

That’s really all there is to it. If you’re new to the
photo game, you might want to invest in a few lessons in
basic photographic techniques, but — once you’ve had
sufficient practice with your new enlarger — you can
be sure that it will really do the job.

And just how good a job will it do? Well, let’s just say
that this former skeptic used her homemade device to
enlarge the pictures that accompany this article. Not too
bad, huh?