Basic Photography Course

When a diffusion enlarger is used, negative defects

are not recorded as clearly in the print, compared to
condenser enlargers. There is an apparent overall

"softening" of the image sharpness and a reduction in
image contrast.

Most of your negatives can he enlarged equally well

with either a condenser or diffusion enlarger; however,
for certain work the choice of enlarger may be an
important factor.

The characteristics of a diffusion enlarger are as

follows:

It should be used for printing negatives that have
been retouched.

It subdues negative defects and grain.

It has less image contrast than that produced with
a condenser enlarger.

It is not suitable for making large prints due to

the softness of the image produced.

Diffusion enlargers should be considered for use in

portraiture and when the negatives have been retouched.

CONDENSER-DIFFUSION ENLARGERS

A condenser-diffusion enlarger or semidiffusion

enlarger is a compromise between the two extremes of
condenser and diffusion. A condenser-diffusion enlarger
uses a diffusion (frosted) bulb and condensers, or a
diffusion bulb with either a diffusing glass over the
condensers, or else one of the condensers itself acts as
the diffuser.

A condenser-diffusion enlarger has the advantages

of a diffusion enlarger to reduce the effects of negative
defects, silver grain structure and dust, and it also uses
the condenser system for speed and uniformity of light.

The enlargers in general use by most Navy imaging

facilities are the condenser-diffusion type. They use
frosted or diffusion bulbs with or without a diffusion
screen placed above the condensers.

ENLARGER LENSES

As with a camera, the lens of the enlarger is the heart

and should be high quality and reasonably fast. It is
senseless to buy high-quality lenses for the camera, then
nullify the quality they provide with an inferior
enlarging lens; however, a quality camera lens is not
suitable for enlarging. Even a moderately good

Table 11-1.Enlarging Lens Focal Lengths for Various Negative

Sizes

Negative size

Lens focal length

35mm

50mm

120 (2 1/4 x 2 1/4) (6x6cm)

75mm

120 (2 1/4 x 2 3/4) (6x7cm)

105mm

4 x 5 inch

135-150mm

enlarging lens is better for enlarging than most camera
lenses.

The focal length you use with an enlarger should be

based on the size of the negative to be enlarged. (See
table 1l-1.) Generally speaking, the focal length of the
enlarging lens for a given negative size should be the

same as a normal-focal-length lens used by the camera
for the negative.

While it is not necessary for the lens to cover the

full area of the negative, the longer the lens focal length,
the less magnification at a given lens-to-paper distance;
therefore, you must have several lenses of various focal
lengths available for your enlargers when you want to
make large prints from small portions of your negatives.

Because an enlarger produces an image from a flat

field (the negative) onto a flat field (the paper), depth of
field is not a factor, except when distortion control
(discussed later) is used. An enlarger lens can usually be

used at large f/stops; however, when an enlarger lens is

used at its maximum aperture, there may be some falloff
of light at the edges of the circle of illumination.
Therefore, an enlarger lens is usually stopped down one

or two f/stops from wide open. Like a camera lens, when

an enlarger lens is used at very small apertures, there is
a loss of image definition due to diffraction.

ENLARGING PROCEDURE

The darkroom design, the equipment, and the

arrangement for enlarging are basically the same as for
contact printing. The safelights should be appropriate
for the type of paper being printed. The size of the prints
may require larger trays and greater amounts of solution,
but they should be set up in the sink the same as for
contact printing.

To produce good enlargements, you need good

negatives, a clean enlarger, clean printing filters, correct
exposure and development, and careful processing and
finishing. Although most negatives can be printed by
projection, there are a few desirable characteristics. A

11-11

contents

Basic Photography Course

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DOFMaster for Windows On-line Depth of Field Calculator DOFMaster for Mobile Devices On-line Depth of Field Table Hyperfocal Distance Chart Articles FAQ Recommended Books Support Contact Links Home As an Amazon Associate I earn from qualifying purchases.	contents <- previous page next page -> When a diffusion enlarger is used, negative defects are not recorded as clearly in the print, compared to condenser enlargers. There is an apparent overall "softening" of the image sharpness and a reduction in image contrast. Most of your negatives can he enlarged equally well with either a condenser or diffusion enlarger; however, for certain work the choice of enlarger may be an important factor. The characteristics of a diffusion enlarger are as follows: It should be used for printing negatives that have been retouched. It subdues negative defects and grain. It has less image contrast than that produced with a condenser enlarger. It is not suitable for making large prints due to the softness of the image produced. Diffusion enlargers should be considered for use in portraiture and when the negatives have been retouched. CONDENSER-DIFFUSION ENLARGERS A condenser-diffusion enlarger or semidiffusion enlarger is a compromise between the two extremes of condenser and diffusion. A condenser-diffusion enlarger uses a diffusion (frosted) bulb and condensers, or a diffusion bulb with either a diffusing glass over the condensers, or else one of the condensers itself acts as the diffuser. A condenser-diffusion enlarger has the advantages of a diffusion enlarger to reduce the effects of negative defects, silver grain structure and dust, and it also uses the condenser system for speed and uniformity of light. The enlargers in general use by most Navy imaging facilities are the condenser-diffusion type. They use frosted or diffusion bulbs with or without a diffusion screen placed above the condensers. ENLARGER LENSES As with a camera, the lens of the enlarger is the heart and should be high quality and reasonably fast. It is senseless to buy high-quality lenses for the camera, then nullify the quality they provide with an inferior enlarging lens; however, a quality camera lens is not suitable for enlarging. Even a moderately good Table 11-1.Enlarging Lens Focal Lengths for Various Negative Sizes Negative size Lens focal length 35mm 50mm 120 (2 1/4 x 2 1/4) (6x6cm) 75mm 120 (2 1/4 x 2 3/4) (6x7cm) 105mm 4 x 5 inch 135-150mm enlarging lens is better for enlarging than most camera lenses. The focal length you use with an enlarger should be based on the size of the negative to be enlarged. (See table 1l-1.) Generally speaking, the focal length of the enlarging lens for a given negative size should be the same as a normal-focal-length lens used by the camera for the negative. While it is not necessary for the lens to cover the full area of the negative, the longer the lens focal length, the less magnification at a given lens-to-paper distance; therefore, you must have several lenses of various focal lengths available for your enlargers when you want to make large prints from small portions of your negatives. Because an enlarger produces an image from a flat field (the negative) onto a flat field (the paper), depth of field is not a factor, except when distortion control (discussed later) is used. An enlarger lens can usually be used at large f/stops; however, when an enlarger lens is used at its maximum aperture, there may be some falloff of light at the edges of the circle of illumination. Therefore, an enlarger lens is usually stopped down one or two f/stops from wide open. Like a camera lens, when an enlarger lens is used at very small apertures, there is a loss of image definition due to diffraction. ENLARGING PROCEDURE The darkroom design, the equipment, and the arrangement for enlarging are basically the same as for contact printing. The safelights should be appropriate for the type of paper being printed. The size of the prints may require larger trays and greater amounts of solution, but they should be set up in the sink the same as for contact printing. To produce good enlargements, you need good negatives, a clean enlarger, clean printing filters, correct exposure and development, and careful processing and finishing. Although most negatives can be printed by projection, there are a few desirable characteristics. A 11-11 contents Basic Photography Course <- previous page next page ->	As an Amazon Associate I earn from qualifying purchases.
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