314
9.
PHOTOGRAPHY
Range of tonal values is great. Grain size is kept small. It is convenient
in that it can be purchased already mixed in cans. It is a fast developer
(3 minutes at 68°F or 20°C in a tray, 25% longer if used in a tank).
It keeps well in a sealed tank and can be used with a replenisher.
Very high contrast developers such as D-l 1 are at times useful for special
reasons, but, they have such a limited gray scale and their grain is so
bad that they should not be used for most purposes. If necessary for particular purposes, a moderate increase in contrast can be obtained without
sacrificing grain if plates are deliberately somewhat overexposed, and
then given a short immersion in a reducing bath after development. Also
"antifog" additives are available.
Investigators who work with 35 mm film in their microscopes have a
special problem in that grain size does effectively limit the quality of their
finished micrographs. There is no happy solution for them except to convert to larger plates where this is possible. This writer knows of several laboratories where Philips microscopes were being used which were pleased
indeed with the immediate improvement in the quality of their work
when the plate camera attachment became available and was first used.
Development is quite dependent upon temperature, and the manufacturer's instruction should be followed with reasonable care if a uniform product is to be produced. In particular, excessively high temperatures aggravate grain size seriously so that there may be days in summer
when one should not attempt to develop plates, or at least temperature
controlled water baths must be used with developing trays or tanks. Although modern developers (except the ultrafine grain ones) have considerable temperature latitude, this must be not exceeded. Plate development is best handled as a standardized operation varying only the time
with the temperature.
9.8. Enlarging
Enlarging negatives to get the most out of them is a considerable skill
which it is necessary to perfect. Many an excellent negative no doubt
has been filed away forgotten because the print made from it was of poor
quality. Some knowledge and several tricks are necessary to get the most
from negatives.
It is quite important to standardize enlarging procedures as much as
possible. A single developer such as Kodak Dektol (similar to D-72)
9.
PHOTOGRAPHY
Range of tonal values is great. Grain size is kept small. It is convenient
in that it can be purchased already mixed in cans. It is a fast developer
(3 minutes at 68°F or 20°C in a tray, 25% longer if used in a tank).
It keeps well in a sealed tank and can be used with a replenisher.
Very high contrast developers such as D-l 1 are at times useful for special
reasons, but, they have such a limited gray scale and their grain is so
bad that they should not be used for most purposes. If necessary for particular purposes, a moderate increase in contrast can be obtained without
sacrificing grain if plates are deliberately somewhat overexposed, and
then given a short immersion in a reducing bath after development. Also
"antifog" additives are available.
Investigators who work with 35 mm film in their microscopes have a
special problem in that grain size does effectively limit the quality of their
finished micrographs. There is no happy solution for them except to convert to larger plates where this is possible. This writer knows of several laboratories where Philips microscopes were being used which were pleased
indeed with the immediate improvement in the quality of their work
when the plate camera attachment became available and was first used.
Development is quite dependent upon temperature, and the manufacturer's instruction should be followed with reasonable care if a uniform product is to be produced. In particular, excessively high temperatures aggravate grain size seriously so that there may be days in summer
when one should not attempt to develop plates, or at least temperature
controlled water baths must be used with developing trays or tanks. Although modern developers (except the ultrafine grain ones) have considerable temperature latitude, this must be not exceeded. Plate development is best handled as a standardized operation varying only the time
with the temperature.
9.8. Enlarging
Enlarging negatives to get the most out of them is a considerable skill
which it is necessary to perfect. Many an excellent negative no doubt
has been filed away forgotten because the print made from it was of poor
quality. Some knowledge and several tricks are necessary to get the most
from negatives.
It is quite important to standardize enlarging procedures as much as
possible. A single developer such as Kodak Dektol (similar to D-72)