BRIEFING PRINT ENLARGER

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04770A000500010007-0
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 6
• Document Creation Date: December 28, 2016
• Document Release Date: October 8, 2004
• Sequence Number: 7
• Publication Date: November 30, 1964
• Content Type: PERRPT

Approved For ease 2004/11130 I DP78B0477700500010007-0
PAR 202
30 Nov 64
t
t
SUBJECT: Briefing Print Enlarger
TASK/PROBLEM
1. To design and build a prototype enlarger for exposing high-
quality briefing prints in formats up to and including 20 x 24 inches
in size. Magnification to be in the 10 - 60 diameter range. The en-
larger will be able to produce both black-and-white and color prints.
Changing from one capability to the other should be made with a mini-
mum of effort.
DISCUSSION
2. This project is proceeding with close correlation to the work
on PAR 224. Work on these projects during the quarter has been on:
a. Vacuum Platen and Carriage
(1)
The layout and detail drawings of the following more
complex parts have been completed:
(a) Platen.
(b) Platen carriage
(c) Carriage track, and
(d) Carriage drive and position indexing assembly
(2) Work has been started on the assembly which will dis-
play the table of magnification and lens focus settings and indicate the
item in the table which corresponds to the platen position.
(3) Two large castings, the platen body and the platen
carriage, have been discussed with engineers in a local foundry and have
been ordered.
(4) About 50 percent of the design and drafting.effort
for the assembly is completed.
NGA Review. Complete
GROUP-.1,
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 Approved For?ease 2004/11 A; pP78BO477000500010007-0
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PAR 202
30 Nov 6L
b. Negative Transport
(1) The first assembly of the breadboard model of this
unit was made during the first period of the quarter. A ball-spline sup-
port for the film spool outrigger arm proved unsatisfactory and has been
'replaced by a ball-bushing and key arrangement. With this spool support,
it has been possible to align the model to run 70mm and 9.5 inches wide
thin base film in both directions. There are random variations of the
tracking of the film into the take-up spool, particularly with 70mm
film, which produces some crowding against the spool flange and slight,
non-permanent turning of the film edge. The film tracking shifts through
a range of about one-eighth-inch at the roll ahead of the take-up spool.
The position of the film web on that roll appears related to the particular
portion of web being run across.
(2) Layout and detail design of back-illuminated transparent
scales for X- and Y-coordinate indication on the transport model are
nearly complete. The major problem has been to design a low-drag, low-
momentum system for the X-coordinate (along frame) indicator to operate
from a film-driven metering roll and which need not be uncoupled when wind-
ing the film at high speed. A system providing similar presentation of
readout to the operator and using several common parts is being designed
for Y-coordinate indication.
(3) Use of the transport for the film tracking tests has shown
that refinement in motor and brake torque controls will be necessary.
c. Main Frame: During the last period, the layout of the main frame
and its shock mounting system has progressed well.
d. Condenser System, Film Gate, and Objective Lens Focus System:
The optical elements of the six condenser systems have been released for
fabrication. It will be necessary to adjust the focus of the condenser
system as the objective lens focus is changed for only the three lowest
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 Approved For lease 2004/11/ftUffP78B0477&00500010007-0
PAR 202
.30 Nov 64
magnification ranges. Mechanical design studies in this area were started
late in the quarter, and no layouts have been established.
e. Objective Lens Designs:
(1) The lens designs required to provide lOX to 60X magni-
fication to 20 x 24 inch prints for PAR 202 and to provide the 3X to 15X
magnification from 70mm square negative area for PAR 224 have been speci-
fied and designed as a series of six lenses to provide a continuous range
of magnification with an over-all conjugate length range of 50 to 80 inches
for each lens. Two series of lenses were specified and designed, one
series for making black-and-white prints with a narrow spectrum band centered
about 4600A and the second series for making color prints with three narrow
spectrum bands centered at 4500A, 5500A, and 6500A. The designs of both
of these series are now complete with the exception of the 40X to 60X lens
in the color series which is expected to be completed momentarily.
(2) These lenses have been designed by the contractor's lens
group on an automatic optimization computer program (LEAD). As the designs
for the color series progressed, there was indication that one series of
lenses could be designed to meet both requirements. By the enc -;,-of the quar-
ter, we had designs for "combination" lenses for three of the magnification
ranges and strong indication that two others will soon be available. A
combination design is not possible for the 40X to 60X range. Table 1 sum-
marizes the lens design effort.
(3) In "combination" lens designs to be used for either black-
and-white or color printing, it appears necessary to operate at about "one
stop" smaller aperture (larger f/number) for color printing in comparison
to black-and-white printing. There will also be a difference in the focus
setting for the two applications. The differences in image quality and
their dependence upon relative aperture and the magnitude of the focus
shift must be measured on the sample lenses.
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 Approved Fo Iease 2004/1
30-L I DP78B0477 00500010007-0
9EC
PAR 202
30 Nov 64
Lens Designs
for
PAR 202 and PAR 224 Enlargers
Magn. Range
and E.F.L.
2.5X to 5.3X
10.7"
4.75 to 9X
7.2"
8.55X to 15X
4.7"
14.5X to 24.7X
3.011
B&W
Printing Only
Form 8-L-11
f/17.8
Not
Designed
Form 4-M-49
f/7.8
Form 4-M-49
f/5.0
Combination
Form 18-L-28A
B&W f/17.8
Color f/26
Form 12-J-25A
B&W f/12
Color f/18
In
Design
In
Design
Color
Printing Only
Not
Designed
Not
Designed
Form 12-M-337
f/12.0
24.2X to 40.2X
1.90"
38X to 62.5
1.25"
Form 4-M-49
f/4.2
Form 28-N-1O1B
f/2.8
Form 6-M-336
f/8.0
Form 6M-338B Form 6-M-336
B&W f/4.2 f/6.0
Color f/6.0
Not
Feasible
In
Design
ALenses released for sample fabrication.
BLenses approved for sample fabrication but not yet released at publication
date of this report.
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 Approved Forllease 2004/1 UC &j3DP78B0477*00500010007-0
PAR 202
30 Nov 64
f. Lens Focus Setting and Magnification Table:
(1) In the enlarger development effort, we are planning
to use manual setting of the objective lens focus. The lens assembly and
the platen assembly are each equipped with precision linear position scales.
The platen carriage drivers are being designed to position the carriage only
at discrete points 0.200 inches apart within its 30 inch range of travel. A
numeric table is to be supplied to show the Lens Focus Scale setting and
the magnification value for each of the 150 discrete platen positions for
each of the lenses.
(2) A computer program in Fortran II for the IBM 1620
computer has been written to calculate the values for the table for each
lens from calibration data of the best photographic focus at three over-
all conjugate lengths. The working of this program is based upon com-
puting adjusted values of lens E.F. and the front-focal-point to rear-
focal-point separation for substitution in the lens formula. Testing of
this program with hypothetical input data showed that the expected experi-
mental errors in the measurement of best photographic focus would create
such large changes in the adjusted E.F. and the focal point separation that
they could not be used safely for computing magnification. The computing
program concept must be revised and the program rewritten.
PLANNED ACTIVITY
3. Effort in the next quarter will be to:
a. Continue test and evaluation of the film tracking characteris-
tics of the negative transport and consider the possible need and means for
servo control of the negative transport. The torque motor and brake controls
will be refined.
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30 Nov 64
b. Complete the objective lens design and begin fabrication of
the remaining five samples.
c. Complete mechanical layouts and detail design and release for
fabrication all parts of the breadboard model.
d. Revise and test with hypothetical input data, the computer
program for the Focus and Magnification Table.
I
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