10X COLOR LENS

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04770A000800080006-1
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 9
• Document Creation Date: December 28, 2016
• Document Release Date: July 2, 2004
• Sequence Number: 6
• Publication Date: October 30, 1964
• Content Type: REQ

Approved For Rile se 2004/07/29 : CIA-RDP78B04770400p800080006-1
PAR 230
30 October 1964
. Declass Review by NGA.
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PROJECT AUTHORIZATION. REQUEST
PAR 230
30 Oct 64
SUBJECT: lOX Color Lens
TASK/PROBLEM
1. Design, fabricate and test a 1OX lens to expose maximum quality
color prints on the 10-20-40X Precision Enlarger.
PROPOSAL
2. Introduction:
a. The lenses delivered on the 10-20-40X Precision Enlargers are
corrected for a narrow wavelength range of light to permit making black-
and-white prints with. minimum loss of information. Recent improvement of
color films and increasing PI interest in color photography make it desir-
able to also provide this capability for making color enlargements.
b. A recent development effort, under another contract, provided
a 20X color lens for the 10-20-40X enlarger. Two concurrent design approaches
were pursued.
(1) A new ten-piece, f/3.0 lens design was provided by
with high theoretical capability but difficult fabrication re-
quirements.
0
(2) A commercial 52.7mm f/2.0~ lens
was installed and tested in a focus assembly of the 10-20-40X
Enlarger for making 20X enlargements.
c. Results of the lens tests showed lower resolving power
pnd considerably less sharpness than the black-and-white original lens.
However, its performance relative to requirements placed upon it by current
color films was adequate.
lens was recommended for 20X color enlargements
and no sample of the new ten-piece lens design was made.
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 Approved For Reiea.L-,e 2004/07/29 : CIA-RDP78B04770AP0 800080006-1
PAR 230
30 Oct 64
APPROACH
3. In the fixed conjugate length of the 10-20-40X Enlarger, a lens
of about twice the focal length of the 20X lens (about four-inches) is re-
quired to provide lOX magnification. It appears doubtful that a "scaled-
up" version of the 52mm
lens would have good enough definition due
to its greater geometric aberrations.
4. A two-part development program is proposed to provide a lens
design suitable for making lOX color enlargements on the 10-20-40X Enlarger.
To shorten the elapsed time, it is suggested these two parts be started at
the same time. The two parts of the program are:
a. Part 1 - Scale up, and modify as necessary,
build a sample lens in a focus assembly for the 10-20-4OX
gnlarger, and make performance tests. Design Specification, No. 469-324 for
this part of the program is derived from the design data for the ten-piece
2OX lens described above.
b. Part 2 - Design a lOX lens to provide image quality comparable
to the 20X lens described above. It appears this might be achieved
ley a seven- or eight-piece design at f/4.0 to f/5.0 with the small six-
to nine-degree semi-field required by the 10-20-40X Enlarger. From this
design, it is proposed to build a sample lens in a focus assembly for the
10-20-40X Enlarger and to make performance tests. Design Specification
No. 469-325 for this part of the program describes a lens of smaller aper-
ture and slightly lower theoretical capability than for Part 1, but which
~s expected to be simpler to fabricate and adequate for enlargement of present
color films and those anticipated over a period of several years.
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 Approved For Release 2004/07/29 : CIA-RDP78BO477OA000800080006-1
PAR 230
30 Oct 64
PROGRAM OBJECTIVES
5. The program objectives are:
a. Part 1
(1) Subcontract
for design of a lens to
Specification 469-324 (minor revision of their Design No. 5829) and fabri-
cation of a sample in a barrel suitable for mounting in a focus assembly
for the 10-20-40X Enlarger.
(2) Fabricate a focus assembly, similar to for
the 10-20-40X Enlarger to receive the above sample lens.
(3) Test the sample lens by making black-and-white and color
enlargements.
b. Part 2
(1) Design an f/4 to f/5.0, seven- or eight-piece lens to
Specification No. 469-325 and fabricate a sample in a barrel suitable for
mounting in a focus assembly for this 10-20-40X Enlarger.
(2) Fabricate another focus assembly as above (paragraph
5.a.(2).
(3) Test the sample lens by making black-and-white and color
enlaaagements.
6. Provide progress and final reports of the development effort.
7. A tentative schedule covering major phases of effort is shown in
Figure 1. The time span indicated to complete the subject program is
based on actual start of work. Upon approval to proceed and/or start of
work, schedule will be reviewed and necessary changes reported as required.
NOTE: Specification No. 469--324, and Specification No, 469-325 are attached.
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 I. Part 1. (Tropel)
Redesign & Fab.
'b. Focus Assembly
c. PITA Test
2 . Part 2 (Contractor)
a.. Design, Optical
b. Design Mount and
Fabricate Sample
c. Focus Assembly
d. PITATest
3. Repor t.s
Informal
a.
b. Quarterly
C. Final
KEY: 0 - Start
11 - Complete
- Deliver
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PAR 230
28 Oct i
MONTHS
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
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22 23 24
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Specification Noe 469-324
30 Oct 64
Design Specification
for
lOX Color Lens for Precision Enlar er
(Modification of
Focal Length: Approx. 4.0". (Over-all conjugate distance 42.80").
Aperture: F/4,0.
Magnification: 20:1.
Short Conjugate Field Diagonal: 1.275",
Long Conjugate Field Diagonal: 12.75"0
Angular Field: Approx. 9?a
Wavelength Range: Three narrow spectrum bands (70 to 100 Angstroms half
pass band width) centered about 4358A, 5461A, and
6563A respectively.
Corner Illumination: Should follow Cos' law if this does not reduce image
quality. No vignetting is a desirable condition.
Distortion: Less than 0.05%.
Performance: In the short conjugate the design goals are:
(a) In the band centered about 5461A, 90% of the rays should
fall within a 3 micron circle over at least 6? of the
field.
(b) In the bands centered about 4358A and 6563A, 90% of the
rays should fall within a 6 micron circle over at least
60 of the field.
(c) Magnification in the three spectrum bands shall be such
that 90% of the rays from the three bands fall within a
single 7 micron circle over at least 6? of the field.
-1-
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Specification No. 469-324
30 oct 64
Special Conditions:
(a) The negative will be registered against the plano sur-
face of a glass element between the film and the main
lens assembly. This element may be a .125" thick plate
(C-1 glass) or it may be a "field flattener" with one
piano surface at the focal plane.
(b) If the lens performance is improved by doing so, the
short conjugate distance in the system can be adjusted
by moving the negative gate between sequential exposures
in the three spectrum bands. The focus movements should
be as small as possible.
Reports Required: Upon completion of the modified design, we require:
(a) Energy distribution curves from ray trace data for mono-
chromatic light at 4358A, 5461A, and 6563A for the axis,
30, 60 and g? off axis. The curves for 4358A and 6563A
should show conditions for the plane of best focus for
these wavelengths and for the best focus for 5461A light,
(b) Reproducible copies of the Spot Diagrams at the same
conditions as in (a).
-2-
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 Approved For Release 2004/07/29 : CIA-RDP78B04770A000 00080006-1
Specification No. 469-325
30 Oct 64
Design Specification
for
lOX Color Lens for Precision Enlarger
(Model 2)
Focal. Length:
Approx. 4,0".
(Over-all conju
ate dista
42
80"
)
g
nce
.
.
.Aperture:
F/4.0 to f/5.0 - May be selected fro
thi
m
s range for
optimum image quality.
Magnification:
101.
Short Conjugate Field Diagonal: 1.275".
Long Conjugate Field Diagonal: 12.75".
Angular Field: Approx. 9?.
Wavelength Range: Three narrow spectrum bands (70 to 100 Angstroms half
pass band width) centered about 4500A, 5500A and 6500A
respectively.
Corner Illumination: Should follow Cos4 law if this does not reduce image
quality, No vignetting is a desirable condition.
Distortion: Less than 0.5%.
Performance: The design goal is to have 90% of the computed rays pass
through a circle of the size indicated in the following table:
Light
5500A (Green)
4500A (Blue) )(1)
6500A (Red) )
4500A (Blue) (2)
6500A (Red) )
Circle Diameter to Enclose 90% of Ravs
0"3- 3
84
(1) At best focus for blue and red light,
(2) At best focus for 5500A (green) light.
64
204
164 324
-1-
Approved For Release 2004/07/29 : CIA-RDP78BO477OA000800080006-1
 Approved For Release 2004/07/29 : CIA-RDP78B04770A('0~00080006-1
Specification No. 469-325
30 Oct 64
Special Conditions:
(a) The negative will be registered against the plano sur-
face of a glass element between the film and the main
lens assembly. This element may be a .125 inch thick
plate.(C-l glass) or it may be "field flattener" with
one plano surface at the focal plane.
(b) If the lens performance is improved by doing so, the
short conjugate distance in the system can be adjusted
by moving the negative gate between sequential exposures
in the three spectrum bands.
Reports Required: Upon completion of the design we require:
(a) Energy distribution curves from the ray trace data
for monochromatic light at 4500A, 5500A and 6500A
on the axis, 3?, 60, and 9 0 off axis. The curves
for the plane of best focus at these wavelengths
and for the plane of best focus at 5500A.
(b) Spot diagrams for the same conditions,
-2-
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