6
NORMAL pH LEVELS AND RECOMMENDED
TOLERANCES FOR ANSCHROME PROCESSING
SOLUTIONS—R—l PROCESS
Solution
Normal
Fresh pH
U seful
pH Range
First Developer
10.20
10.15 to 10.25
First Developer
Replenisher
10.25
10.20 to 10.30
Short Stop Hardener
4.50
4.40 to 4.60
Short Stop Hardener
Replenisher
4.10
4.00 to 4.20
Color Developer
10.60
10.55 to 10.65
Color Developer
Replenisher
10.75
10.70 to 10.80
Bleach
5.20
5.10 to 5.30
Bleach Replensiher
5.20
5.10 to 5.30
Fixer
9.50
9.40 to 9.60
Fixer Replenisher
9.50
9.40 to 9.60
Stabilizer
6.90
6.60 to 7.20
Final Rinse
7.00
6.90 to 7.10
TABLE 4
pH LEVELS USED BY COAST AND
GEODETIC SURVEY FOR PROCESSING
EASTMAN MS EKTACHROME FILM
Normal pH Useful pH
Range
First Developer
10.0
9.5 to 10.5
Hardener
3.0
2.8 to 3.2
Color Developer
11.4
10.9 to 11.9
Clearing Bath
4.5
4.2 to 4.8
Bleach
7.5
7.0 to 8.0
Fixing Bath
4.5
4.2 to 4.8
Stabilizer
6.3
5.8 to 6.8
TABLE 5
Reflective Type Color Prints: Reflective type prints are
not essential for aerotriangulation and stereoscopic compilation
with color photography but they are very useful during these
phases for marking pass points and we find them very valuable
for field work, that is, for control identification and for anno
tation of special features. Consequently, we installed equipment
for producing contact scale color reflective prints and the system
is now working quite well. Actually, the routine production of
good quality reflective type prints has been one of the most
difficult phases of our development of color processing. This has
been due in part to the need for working out adequate quality
controls and procedures and also to the fact that the available
materials have not, until recently, been entirely adequate for
reproduction of aerial photographs.
We are making these prints on Ansco Printon material.
This is a reversal material possessing the high resolution needed
for aerial photography. The General Aniline and Film Corpor
ation have greatly improved this material over the last few years
and today it is far superior to what we started with just a short
time ago. In our laboratory, which is relatively small, one man
can now produce about 100 good quality reflective type contact
scale color prints per day compared to a production of about
250 black and white prints. The Eastman Kodak Company has
recently furnished us with a special Kodak Ektachrome paper
that we are now testing.
We use a LogEtronic contact printer having a full-spectrum
cathode ray tube for exposure. Proper exposure and color bal
ance are obtained by using the rigid full-spectrum light source
and a cone-shaped hood to cover a 9 x 9 inch transparent format.
A MacBeth Quanta-Log color analyzer is incorporated in this
system. The integrating system avoids the need for multiple
densitometer measurements to control color balance and ex
posure time. Only a few seconds are required to make the
readings necessary to control exposure. The prints are processed
in a Rolor processing unit built to handle the full size 9x9 inch
aerial prints. Processing is done at 75° F. using Anscochrome
80° chemistry. This simplifies the water temperature control
problem since all the laboratory operations can be performed at
this single temperature. Sensitometric strips are processed along
with each Printon run. The pH readings are taken prior to the
start of processing.
Color enlargements are desirable for some of our field work
but we are not yet equipped to make these on a production
basis. We have equipped our existing Salzman enlarger with a
full-spectrum light source to make occasional enlargements;
eventually, we intend to obtain a new enlarger witn a high in
tensity full-spectrum light.
I might add that we have made up to 20 diameter enlarge
ments, the limit of our present enlarger, from photographs
taken with the new color films without a granular breakdown.
I mention this because some have questioned the practical
degree of enlargement from color aerial transparent films.
Color Diapositive Plates: The Eastman Kodak Company
forged the last link in the chain of color photography for metric
photogrammetry when they furnished us with experimental
color plates in the fall of 1963. These plates are now in pro
duction and available for purchase. We have used them contin
uously for about a year and have found no reason to regret our
original enthusiasm. The plates are made by laminating Kodak
color duplicating film on l A inch glass. The color balance,
contrast, granularity, and resolution are all excellent and metric
stability is equal to that of the black and white emulsions or
dinarily used for aerotriangulation. For testing plates, we print
a master grid onto the plate in the vacuum printer with a point
light source and then measure this grid on a comparator. The
standard error on a single grid intersection coordinate on the
color plates after a least squares fit for correspondence was less
than 2 microns (1/12,000 inch).
The printing and processing of the plates are handled in
the same manner as Kodak color duplicating film of this same
emulsion. The plates are exposed in the LogEtronic printer
with the automatic dodging feature at the maximum setting.
Exposure times on the printer have ranged from 15 to 30
seconds.
The plates are processed in special baskets, as shown in
figure 20, using a nitrogen burst system. The use of the nitrogen
burst system assures even processing and density throughout
the run and our arrangement has a capability of 39 plates per
run using three baskets.
The plates are processed with standard Kodak E-2 and E-3
chemistry as shown in Table 6. In our laboratory we can handle
two processing runs per day, one in the morning and one in the
afternoon, with a total production of 78 plates with two men
operating the system, one printing and one processing.