DEAR ART:

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A001700070029-6
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 14
• Document Creation Date: December 28, 2016
• Document Release Date: July 13, 2001
• Sequence Number: 29
• Publication Date: June 1, 1961
• Content Type: LETTER

Approve or Release 2001/08/13: CIA-RDP78B 747AO01700070029-6
Declass Review by NIMA / DoD
June 1, 1961
We are contemplating a vacuum print stock easel for
the new 10-20-40X Precision Enlarger which registers the print
stock on the base side rather than the emulsion side as was the
case in the 20X Precision Enlarger. As a part of the contemplated
vacuum easel design a micrometer "focus" adjustment is provided,
primarily to permit adjustment of the magnification ratios with
various objective lenses to nominal values. This adjustment can
also be used to compensate for gross variations of print stock
base thickness as between glass plates and film or paper. This
design approach permits a simpler and more rugged vacuum easel
design at the cost of a slight loss of convenience in operation
if glass plates are to be mixed with film and paper as print raw
stock.
If you are considering the purchase of the new 10-20-
40X Enlarger, will you tell us whether you plan to use glass plates
and to what extent? Also what thicknesses and sizes would you use?
Would the necessity for using a paper or plastic mask on glass
plates (if you desire a clear border) be a great inconvenience?
 Approved For Release 2001/08/13 : CIA-RDP78BO4747AO01700070029-6
Approved For Release 2001/08/13 : CIA-RDP78BO4747AO01700070029-6
 ApprovedrGor Release 2001/08/13: CIA-RDP78B 47AO01700070029-6
DESIGN SPECIFICATION
FOR 10-20-40X PRECISION ENLARGER
10 GENERAL DESCRIPTION
The enlarger will be used to make high quality lO-2O.40X enlargements
from portions of aerial photographs respectively .900 x .900; 01,.50 x .150;
,,225 x 6225. Accommodation will be provided for the following unperforated
films 70mm (2.751"?0010), 5"( .960"{-0010)., 6.6?,(60590"+0010), 7A(60991"?,010),
8" (70960"?0010), and 9j" (9.46o"t.010) 0 With relatively minor modifications,
the enlarger can be adapted to.accept other sizes. The selected sections
will be enlarged, through a liquid gate, to form an image on a 9 x 9 area
of a 10 x 12 sheet film held flat by a vacuum easel. The condensing system,
the objective lens, and mechanical components will be designed to give
optimum resolving power under these conditions.
II0 PHOTOGRAPHIC MATERIALS TO BE HANDLED
A0 The photography will be supplied on spools 70mm to 9a" wide. It may
also be supplied on two spools; that is, the film may have been
partially wound onto a take-up spool.
B. The aerial film will be supplied in lengths up to 500 feet. The
first and last frame to be exposed, however, will be at least 1400 from
the end of the roll. > y
C a The raw stock used will be 1.0 x 12 sheet f ilm o The photographic
exposure will be in the spectral range 4100A to 4300A. (-4.,..A 4,14)
III. GENERAL CONSTRUCTION
A0 Over-all Arrangemment
10 The optical and mechanical assemblies that make up the enlarger
will be mounted on a rigid metal frame. The upper portion of the
unit will consist of the lamphouse, condensers, supply and take-up
spindles, film gate i.th liquid injectors, air squeegees, idler rollers,
Approved For Release 2001/08/13 : CIA-RDP78BO4747AO01700070029-6
 DESIGN SPEC
r lea ,x2001/08/13: CIA-RDP78BQk747A001 @*B?24V1
tension rollers, mechanical film transport controls, illuminator
box, and objective lens. The lower portion will consist of the
easel and base for sheet film.z
2. The enlarger will be approximately 75" high, 142" wide (film flange
to film flange), 32" deep and weight approximately 900 pounds.
3. The enlarger base, will stand on the floor. The enlarger itself
will be isolated from its base with vibration dampers.
4. The height of the negative gate will be approximately 57" above
the floor and the height of the easel will be approximately 14".
B. Construction and Function of Main Components
pw~r~lI M mil
1. The films will have a disk type antibacklash clutch, a magnetic
brake,, a knob for slow film rewind and a crank for rapid rewind.
The supply will accommodate all the sizes specified (General Descrip-
tion) on standard aerial roll film spool up to 500 feet.
f~.0 _
U.S. Air Force Spool
(70m)
U.S. Air Force Spool
(5")-
U.S. Air Force Spool
U.S. Air Force Spool
(7")f')
U.S. Air Force Spool
8 n
U.S. Air Force Spool
(94n)
Slight modifications of the system will permit the instrument to
accept other sizes. The magnetic brakes will be energized, locking
the negative-in place, as soon as the area to be enlarged has been
selected.
2. The Film will be of the liquid type; however, the film will
not be submerged in a liquid. The liquid will be injected manually
upon both sides of the film at the gate just prior to clamping for
printing. The upper 'part of the gate will consist of a spring
loaded condenser lens piano on the side which contacts the film.
The lower part of the gate will consist of a disk (approximately
1.750" dia) of .125" optical glass with a refractive index of
Approved For Release 2001/08/13 : CIA-RDP78BO4747AO01700070029-6
 DESIGN SpIAgyMXqcJ4:ff Release 2001/08/13: CIA-RDP78BQ 747A0017000709,?&9-619, 1961
FOA O2 ETC MS ON ENLARG. R Page 3
1.523?,010 and of excellent surface quality.. Both the upper and
lower parts of the gate will remain fixed on the optical axis
while the film is moved forward or backward in search of the
area to be enlarged. (See Cross Feed) While the lower part of
the gate is adjusted to fall exactly into the focal plane of the
optical system, the upper'or spring loaded part will move up
approximately 22". to ease the interchanging of lenses. In its
normal position, the upper gate will clear the. leer gate by .060".
This spacing will allow the film to pass freely and will also
permit the injected liquid to wet the glass as well as the required
negative area. In this position it will be possible to inspect
the image on the easel prior to clamping. A downward movement
of the condenser lens clamps the film under spring pressure during
exposure. Interlocks on the film transport and arosefeed mechanisms
prevent any movement of the film while it is clamped in expose
position,
In changing magnification, a condenser lens and call ase bl7
between the lamphouse and the film will be replaced.
The. .tae-.u will be the -same as tae-supply, 5i (
Objective Lens a Three quickly interchangeable lenses will be
provided; a M-1?1C Type 93= f/2 for lOX magnification, a 14-171A
Type 50mm f/2 for 20X magnification, a M-171D Type :264mm f/2 for
LIOX magnification, All three lenses will have fixed diaphragms,
The resolving power of the negative material may range up to 200
lines per mm. The optical performance at 20X shall match that
achieved in the 20X Precision ;nlarger. Because of the increased
geometrical aberrations of the lens as "scaled up" for IOX, the
resolution at the negative may be decreased. Conversely, in the
Approv or Releafe zvo 908 *Rd
R6~ PAO'OTTUOQ70II g_%f 400
lines per mm or more in the center of the field. Test of the
 DESIGN SP M2 Release 2001/08/13: CIA-RDP78BW47A001700qMP2b6 1961
0 PRECISION II11 LARGER
Page 1t
instrument should be made in the 4,1OQA to 4,300A,. range as
limited by using a second order Fabry-Perot filter.
In changing magnification, a second assembly consisting of the
lower plate of the negative gate and the objective lens will be
replaced, A micrometric device to permit the lens to be focused
relative to the gate is included in this assembly. Since the
critical (for focus and alignment) dimensions of lens to gate
relationships are set and held in this assembly, it is probable
that test prints to verify enlarger alignment following magnifi-
cation changeover will not be required.
NOTE: Storage space will be provided for the lenses and other
interchangeable assemblies.
6, The Film Transport Assembly will, consist. of a vertical plate
straddling the lamphouse. This plate will hold the supply and
take-up spindles with their cranks and clutches, er -ar4 . ten-
lion rollers .a6 k cam.
This complete assembly will crosefeed back and forth on guide rods
equipped with ball bushings Two handles, one on each side of
the enlarger, will permit the, assembly to be pushed, or pulled,
to position a designated area of the negative in the printing
beam, An interlock in conjunction with the tension arm will
insure that the film is pulled taut before it enters the squeegees.
The movable assembly will be normally held stationary by a magnetic
brake. In order to generate any movement it will be necessary
to gently squeeze the handle located on the right as this pressure
will release the brake. (This pressure also operates the squeegees)
order to safeguard the negative when the negative gate is clcssed,
an interlock will override the ability of the "squeeze handle" to
441FI& 4 fff IgQ a 2%4/W8 j ,-
86 k% 18pur4 4jA ,117.0 Ot7h0e negative
 .DESIGN Sp '~tl'lp 8 Release 2001/08/13: CIA-RDP78BQ 747AO01709%0139-.961
FOR 10-24- OX .PRECISION ENLARGER Page _ 5
to be transported; past the optical axis, to position itself
on a diffuse illuminator located in front of the enlarger. This
illuminator will be large enough to permit inspection of the frame
or code number on both edges of a full frame of the widest film
(9 ")O Furthermore, a metering device will determine the "across
frame" co-ordinate of the area of the negative in the printing
gate in respect tot -r ar- --o _ (See illuminator
111
and Negative Area Selector.)
7. A pair of Tubular Air Squeegees will be used to remove the liquid
from the film. The squeegees will be mounted horizontally close
to the negative gate, symmetrical to the gate and parallel to
the film web, This unit will also be positioned at an angle of
approximately 3? off the line perpendicular to the web in order
to allow the edge of the film to progressively enter the squeegees.
The film will be held taut between a pair of rollers while it is
crossfed between the squeegees. Toremove liquid from the film,
the Film Transport Assembly must be pulled forward to move the
film through the squeegees.
The squeegee air supply is turned on by the same electrical
asset which releases the brake holding the film transport assembly.
As the film is moved through the squeegees, the liquid will be
atomized and blown toward the back of the instrument where a hooded
exhaust fan will carry the fumes away, Due to the requirements
of this design, it will be necessary to move the film between
the squeegees at times when no removal of liquid is desired.
Whenever the film is in motion between them, the squeegees will
be energized creating a cushion of air preventing scratches. To
facilitate the interchanging of lenses, the squeegees will be pulled
AiR&4Fgja5el M J%g1//jtj3 : CIA-RDP78BO4747AO01700070029-6
 DESIGN SPE s ' r Release 2001/08/13: CIA-RDP78 47A0017 7hg?9] I
OR 0-20 T ON ENLkRGER Page 6
The illuminator (approximately 10"x IM will be located in front
of the enlarger to permit inspection of a full frame Hof the widest
film (92"). The unit will consist of a shallow box housing
fluorescent lights and covered by a sheet of opal glass. This
opal glass will be bisected by an index line directed from front``
to back, in line with the optical centerline (Y axis). A similar
line (X axis) will be located toward the back of the glass and
oriented at 90? to the Y axis. The top surface of the box will be
free from any protrusions and sharp edges capable of scratching
the film. The illuminator lamps will be controlled by a guarded
toggle switch in front of the illuminator. The forward position
of the transport assembly,, where the film path is over the illumin4
ator, is also the position for loading the negative.
The illuminator assembly and the air squeegees will be fastened to
a common base so that both units can be pulled forward to provide
space for the interchange of lenses.
9. The Co-ordinate Searching Device e Given the X and Y co.=ordinates
(in-frame coordinates) of the center of a selected area of a
negative, an operator will be able to position this area enact
in the printing beam. The searching device is composed of the
/I
illuminator, one metering roller which measures and records on
a dial the film length along the X axis and one roller and recorder
which does the same on the Y axis.
To find a given area designated by numerical values for X and Y
the negative is placed over the illuminator so that a
of the negative frame coincides with the Y axis and A&-e4
with the X axis. The X recording dial is zeroed and the film is
transported until the X value is read. Then the film transport
dial
 DESIGN SP ', C_ a ass 2001/08/13 :CIA-RDP78BQ 447A001700019t 21B9E; 1961
FOR a n?2n-r
UUX %~.,~~~ N M.ARGER Page w 7
reads the required value for Y. It is not necessary to zero the y
dial each time because it records from a fixed point. However,
when changing negative sizes a quick adjustment of the metering.
device is necessary to compensate for different margin sizes.
10. The house will have a 300 watt (ASA code CXP) biplane filament
projection lamp to obtain a uniform illumination of the objective
lens aperture. To insure that the exposure'time is never less
than that of which the timer is capables a variable autotransformer
is provided to control filament brightness. A 1% ammeter will be
included in the circuit. A blower mounted off the enlarger frame
will cool the lamphouse. The optical system will consist of three
lenses for the first condenser, a heat absorbers a 45' front surfaced
adjustable mirror, a holder for a color filter to improve the
resolving power of the lens, a' field lens, an adjustable iris dia-
phragm, and film plane condenser lenses. This unit at 20X will
produce an exposure in,10 seconds on 7402 (Kodak.Fine Grain Positive
Film) with no negative In the gate which will develop to a density
of 1.0 or greater with 3 minutes processing in DK450 developer at
68?F. The exposure at I'M will be 50% to 70lese and at 40X'2 to
4 times greater. The three condenser elements nearest the=film
plane will be designed to be quickly interchangeable in a cell
assembly with new condensers matching the 26mm (40x)s 50mm (20x),
and 93mm (lOx) objective lenses. This condenser change will necessi-
tate a vertical displacement of the lamphouse. This displacement
will also be quickly achieved*
no The easel will retain a sheet of film 10 x 12, tbfiak.
This easel wjll hold the fin flat ' by vacuum. Provj sjon w jll by
made t o . evacuate the &# .between the film arol the "easel board"
Q%WWttd a 2di1 tt3on;IdfRQJ7> JJ7yfi0QM8$07.@O ed masks
 ESIGN SPECIFICATIONS May 19, 1962
CIS " ENLARGER paw
Appr o d*pi- Release001/08/13: CIA-RDP78B0 7A00170Q~Rn)2
11,4
12,
A printing box installed on t e back of the mask will contact
on tOp of the easel, will allow for a 9 z 9 image with a 2
maximum corner radius. Edge stops on the easel will provide
margins J" wide,on three sides and 22" wide on the fourth side,
print type written identifications on the 2J" margin of the film.
The easel assembly can be rotated without stops about the optical
axis to provide any desired orientation of the image. Provision is
also made for micrometer up and down adjustment and locking of this
easel with a range of 2", This will permit the magnification for
each of the lenses to be set to the nominal value within the
limitations of the ability to measure magnification.
Air Pressure and Vacuum -e A regulated oil free filtered air supply
will be furnished for the air squeegees. At 50 pounds air pressure,
one pair of air squeegees will consume about 15 cubic feet per -A-P,y,,
m of j , The vacuum will be used to hold the film on the
easel. A combination vacuum pump and compressor may be used with
two separate tanks,
13. The liquid injectors will consist of two pharmaceutical syringes
modified to accommodate the 1,1,1 m trichloroethane and tetrachloro.
ethylene. This liquid has an index of refraction equal to that
of the film base (1,48t.02). The injectors are manually and
simultaneously actuated by a lever on the left side of the enlarger,
(refer to the Film Gate) The stroke of the lever will be adjusted
so that only the required amount of liquid is dispensed.
14. The liquid reservoir consisting of a glass jar will be located as
close as possible to the injectors. Three sizes will be available:
1 pint, I quart and 2 quarts. These jars will be easily removable
for cleaning,
Approved For Release 2001/08/13 : CIA-RDP78BO4747AO01700070029-6
 DESIi3N S~ Please 2001/08/13 : CIA-RDP78B(J747AO01700070029-6
FOR 10-20-40X WG IS ION ENLARGER May 19, 1961
Page -'q
I5a An - stem will be provided to remove the fumes which are
moderately-toxic0
Static Eliminators
g i
o
e
en
, ~~~
.
/
ac s b
two refezirfc lines./ See Co-ordinates Searching Device)
19. A tension vs.
*r will keep the files.taut, .030" above the lower
bok gate... This tension is required to allow the film to pass between
AAIII~
180 TwoImeterin rollers will be parjf,.4 the co4odinate search
will be provided.
170 Idler rollers will support the film at its ed ea and keep the film
i n a v path as it passes through the dtiet removal attachments.
These rollers will have a stationary rear flange and an adjustable
front flange designed to accommodate the film sizes specif ied0
(General Description) One of the rollers adjacent to the squeegees
will be used in conjunction with .
the squeegees.' It also keeps the film flat to permit inspection
of the image on the easel.
20. A stripper ~.late and roller aseemb will be fitted around the
lower negative gate. A polished guide plate with two highly
polished rollers will prevent the edge of the film from stubbing
against the lower gate and will also allow the wet film to detach
itself from the gate where it might be held by surface tension.
The top of the rollers will be ;030 above the surface of the lower
gate and the stripper plate 4140 below the gate. This asaembly
will be easily lifted out to give access to the objective lens.
210 During'the time that the negative is clamped in the gate, the
motors on either the inner or outer frame of the enlarger will be
Ao ova Q For ey a urned220001//0 /13 : CIA-RDP78B04747A001700070029-6 off.
 Approved r Release 2001/08/13 : CIA-RDP78BQ&747A001700070029-6
DESIC}N SPECIFICATIONS May 199 1961
FOR 1-r-20-40X PRECISION ENTARGER Page - 10
IV0 , EXPECTED PERFORMANCE
A. The resolving power of the 70mm to 9P film may be in the order of 100
d --L-t,4-4-Lt ? II
lines per M. It is desired to exploit as much of that definition as
is possible,, The enlarger and all of its components will be of high
quality and will be adjusted to give maximum performance to provide a
minimum of loss of information between the negative and the print,,
B. The enlarger shall be rigid enough and shock mounted ao that vibrations
in the structure where the unit will be used will not cause deterioration
of the image over the maximum exposure time under normal conditions,,
C, The film gate-shall be.constructed so that scratches are minimised,
Defects on the gate or bubblea in the liquid shall not
be evident in the enlargement,
V, OPERATION
Ao The work area will be at the front of the enlarger, The controls pro-
vided for moving the film in either direction will be positioned so
that the operator can reach them conveniently while viewing the film
on' the illuminator,
B,, Sequence of operation for loading the negative
1. Pull the.Film Transport Assembly over the Illuminator,,
2, Place the two reels over the spindles.
3o Thread the film.
C. Sequence of operation for changing magnification
Lift on handle to raise Condenser barrel (Upper date); remove the
Pull the Film Transport Assembly over the Illuminator,
Pull the Illuminator & Squeegees to front stop,
bagel assembly,
li, L U% Stripper Plate and Roller Assemblies.
51 1, rovecPPA?* IX9s 1/08/13: CIA-RDP78BO4747AO01700070029-6
 DESIGN 8PE Release 2001/08/13: CIA-RDP78BQAF47AO01 700%W221961
FOR 10- 0m & X PRECISION ENLARGER Page ? 11
6, Replace objective lens (different focal length).
7. Put Stripper Plate and Roller Assemblies back in place.
8. Replace Condenser barrel assembly corresponding to the objective lens.
9. Pull spring loading wrist pin and allow it to drop into appropriate
hole. (This repositions the lamphouse)
10, Push Illuminator and Squeegees in place.
11, Move the easel to preset position corresponding to the new magnifi-
cation. ~~-
12. Push down on handle to lower upper gate to "compose" position. Ready
for operation, Approximate time 4 minutes.
Do ? Sequence of operation for enlarging
1. Find co-ordinates of area to be enlarged and slide under the gate,
2. Verify projection over the easel and orient easel if neeeasaryo
no Pull Film Transport Assembly pas he Squeegees to the Illuminator.
12. Ready for selection of new area.
VI. MAINTENANCE
All parts'will be accessible for lubrication and servicing.
VII. ENVIRONMENT
4o Inject liquid,
Clamp gate.
6o Load easel,
7. Expose.
8o Remove exposed stock,
9, Lift gate.
100 Inject liquid (washing operation),
30 'Set timer, 11
A. Space required for the enlarger to provide convenience in operation and
maintenance should be approximately 6J ft wide and 5 ft deep.
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 tR
DESIGN SPEC rF a 2001/08/13: CIA-RDP78B~747A0017fO7 9 6l
FOR 10-20?. 0 E~II~ Page o 32
B. The enlarger will be used in a photographic darkroord preferably air-
conditioned,, to be dust free and in a temperature range 60? to 85?F.
Relative humidity is unimportant except as required by the sensitized
goods and the negative,
C, The lamphouse will not permit extraneous light to escape into the room;,
VIII0 APPEARANCE
The exterior of the enlarger will be gray enamel; its interior will be
dull black, The mechanism above the lens will be polished chrome and
nickel plate or stainless steel except for the light path, This path
will be dull black,
IX. ELECTRICAL SPECIFICATIONS
The enlarger shall operate on 115 volt'. 60 cycle source of power, A
commercial laboratory timer will be provided. The timer will be conveni-
ently located for ease of operation. The air compressor and vacuum pump
will operate on 115 volt., 60 cycle,. single phase source of power.
X. OPERATING INSTRUCTIONS
Informal operating and maintenance instructions will be supplied., but no
allowance is made for field trips., installation or servicing.
/ / -
~,' _ s ~,f,,.s~?~-`L,e.,.t,,,'(ic_,~-i,, .~Ci~/.~G- -.OLD-..,~- ~.~/LtLrl ~L,G;~4.f~'
Approved For Release 2001/08/13 : CIA-RDP78BO4747AO01700070029-6