Black and White Photography

Like camera lenses, enlarging lenses are classified according to their maximum
aperture. Thus an f/2.8 enlarging lens is faster than an f/4 lens, because it
allows more light through when set at its maximum aperture. More light makes
it easier to see and focus the projected image, and gives you the option of using
a shorter print exposure time by using a larger f-stop.
Enlarging lenses, like camera lenses, are categorized by their focal length.
When choosing a lens, you must consider the size of the negative you are printing.
The minimum size focal length for an enlarging lens is roughly the same as
the focal length of the normal lens on the camera that took the picture. Since
50mm is normal for a 35mm camera, you will need at least a 50mm enlarging
lens to enlarge a 35mm negative.
The reasons for this are related to a lens’s covering power—the circle of illumination
the lens projects. The circle’s size is related to its focal length; generally
the longer the focal length of a lens, the broader its covering power.
This is why you can print using a longer-focal-length lens than recommended,
but not a shorter one. For example, an 80mm lens projects a circle of
illumination broad enough to cover a 21⁄4" x 21⁄4" negative, so it also will cover
the smaller-size 35mm negative. However, the same 80mm lens does not project
a broad enough circle to cover a 4" x 5" negative; for that amount of coverage
you will need a longer lens (at least 135mm).
At a given height, the focal length of the enlarging lens determines the size of
the projected negative. A longer-focal-length lens projects a smaller-size image
than a shorter-focal-length lens, so an 80mm enlarging lens will project a
smaller image than a 50mm lens. Thus, the longer the lens you use, the higher
you must raise the enlarger head for enlargement. Furthermore, the higher you
move the head, the weaker the light and the longer it takes to expose the printing
paper, assuming you are using the same lens aperture. This means that
choosing a focal length longer than required could result in longer print exposure
times.
The following chart lists the minimum-recommended-focal-length enlarging
lens for use with different-size negatives.
Negative Size Minimum Focal Length
35mm 50mm
21⁄4" x 13⁄4" (6 x 4.5 cm) 75mm
21⁄4" x 21⁄4" (6 x 6 cm) 75–80mm
21⁄4" x 23⁄4" (6 x 7 cm) 90mm
21⁄4" x 31⁄4" (6 x 9 cm) 100–105mm
4" x 5" 135–150mm
Negative carrier. A negative carrier is a device that holds a strip of negatives flat
and in place in the enlarger. Each film format usually requires its own negative
carrier. So if you use different film sizes, you will need a different carrier for each. The carrier has a top and a bottom part, sometimes hinged together or sometimes
as separate pieces. Both top and bottom have a rectangular or square
opening the size of a single negative frame. When placed in the carrier, only the
image to be printed shows; the rest of the negatives on the strip are masked out.
The opening of most negative carriers is uncovered. There also are glass negative
carriers, which have a thin sheet (or two sheets) of glass covering the opening
to help keep the film flat. You have to handle glass carriers with special
care, as dust, smudges, and scratches on the glass may show up on the final
print or otherwise degrade print quality.
Variable-contrast (VC) filters. Called variable-contrast, polycontrast, or multicontrast
filters, these plastic filters fit in the enlarger, usually in a drawer located
below the light bulb. They come in kits containing 10 or so separate filters
numbered in half-step increments from #0–#5 (#0, 1⁄2, 1, 11⁄2, 2, and so forth).
The lower-numbered filters are pale yellow and decrease print contrast, while
the higher-numbered filters are magenta, or sometimes reddish-orange, and
increase contrast.
Variable-contrast filters are effective only with variable-contrast printing
papers, the most commonly used black-and-white photographic papers. These
papers produce a range of print contrasts depending on which filter you use to
expose your paper.
You can buy variable-contrast filter sets in different sizes, such as 3" x 3" or
6" x 6". Make sure your filters fit into your enlarger’s filter drawer; trim them
to size if they are too big.
Different brands of variable-contrast filters are generally compatible with all
variable-contrast papers; for instance, you can use filters from Kodak with
Agfa papers and vice versa. However, filters might produce slightly different
results from one paper type to another. For best results, paper manufacturers
generally recommend using their own brand of filters.
Timer. An enlarging timer regulates print exposure times accurately and conveniently.
There are analog and digital models available. Digital timers allow
incremental exposures in fractions of seconds and are generally more precise.
The enlarger’s power cord fits into an outlet on the timer. There is a focusing
switch on the timer that allows you to turn on the enlarger light so you can set
up and focus the image. When you are ready to expose the printing paper, you
turn the switch to its timer position, set an exposure time, and then press a
button on the timer. The timer turns on the enlarger light for the set time and
shuts it off. On most models, the timer then resets to the specified time, ready
for the next exposure.Focusing magnifier. A focusing magnifier enlarges a portion of the projected
image, allowing you to see and focus it more critically. Grain focusers provide
the most magnification, allowing you to see the individual grains of silver that
make up the image. When the grain appears sharp, the image will be in sharpest
focus.
Trays. Processing trays, made of chemically resistant plastic (or sometimes stainless
steel), hold chemical solutions used for print processing. You will need at
least four trays. Standard sizes include 5" x 7", 8" x 10", 11" x 14", 16" x 20",
and 20" x 24". Make sure your trays are large enough to accommodate the
largest sheets of paper you will be working with in a particular printing session.
Apron. A plastic, rubber, or cloth apron dedicated to darkroom use helps keep
chemicals from staining your clothes.
Towels. Have clean cloth towels or paper towels on hand to keep your hands
dry when printing. You will have to rinse your hands regularly to minimize
chemical contact with skin and to keep paper, equipment, and chemical solutions
from becoming contaminated. Towels also are helpful when mopping up
spills of chemical solutions.
Tongs. Instead of your fingers, you should use tongs made of stainless steel,
plastic, or wood to handle wet printing paper and carry it from tray to tray.
You will need at least three pairs of tongs—one each for the developer, stop
bath, and fixer—to avoid chemical contamination, which can lead to print
staining or other deterioration.
Safelight. Printing papers are sensitive to light, but with black-and-white papers
you can safely use a dim amber-colored light to illuminate the darkroom when
printing. There are several types, but simple safelights are 15- to 25-watt bulbs
in a housing covered with a colored filter. A single safelight should be sufficient
to illuminate a small darkroom, while large darkrooms may need two or more.
Safelights are not totally safe. They can still fog (inadvertently expose) printing
paper under certain circumstances. Make sure the safelight is at least 3 or 4
feet away from the paper, and don’t leave unexposed paper out of its box or
envelope for more than a few minutes.
Easel. A metal easel holds printing paper under the enlarger. It generally consists
of two parts: a base to position the paper on and a hinged top to hold the paper
flat with the help of two or more adjustable blades. You set the desired image size
by adjusting the blades along a ruled molding on the edges of the hinged top.