June 21, 1927.

1,633,228
E. 0. ROGERS
PHOTOGRAPHIC ENLARGER
Filed April 8. 1926

' Irél.

17
 Patented June 21, 1927. 1,633,228
UNITED STATES PATENT OFFICE.
ELWOOD C. ROGERS, OF INDIANAPOTJS, _
PHOTOGBLPHIC ENLABGER.
Application filed April 8, 1926. Serial K0. 100,587.
It is the object of my invention to pro The support for my enlarger comprises
duce a photograhic enlarger of the re?ector two parts, a base 10 and a stand 11 to which
type which is more economical to manufac the enlarger (proper is attached. The base
ture, and more effective in use, and more 10 is provide with a foot 12 adapted to be 60
easily operated than other enlargers of this secured to table-to 13 or any other hori
type heretofore made. More speci?cally it zontal surface. Ne r its top,‘ the base 10
is myobject to construct an enlarger which has a part 14 which projects parallel to the
will evenly illuminate the negative and the plane of the foot 12 and horizontally out
projected ?eld, which will avoid uneven ward oppositely to the foot 12 and is adapt
heating of the negative and consequent ed to have attached to its upper face, as‘ by‘
warping of ?lm negatives or possible break
ing of glass negatives; which will produce screws 15, a foot 16 at one end of the stand
11. At its opposite end, the stand 11 is pro
an evenly illuminated ?eld irrespective of vided with a second foot 17 and between the
the distance between the negative and the feet 16 and 17 is preferably a reinforcing rib 70
lens; and which will employ usefully a 18. The stand 11 may be removed from the
larger proportion of light rays emitted from base 10 and placed in a horizontal position,
the light source than will other enlargers of as indicated in Fig. 7, with the feet_16 and
the re?ector type heretofore used. A fur 17 resting on the table top 13, the foot 16
ther object of my invention is to produce being bifurcated as is clear from Fig 2 in 75
an enlarger which may be used to project order that a stable support for the enlarger
either vertically or horizontally. . may be provided. '
I accomplish the above objects by employ A longitudinal slide 20 is affixed to the
ing an enlarger ‘with the usual lens, and a stand 11 in any suitable manner such as by
source of light in the form of a frosted or means of the screws 21. Desirably the sides 80
25 etched or coated light bulb. I provide for of the slide 20 are rounded, as is clear from
this light bulb a non-diffusing re?ector (or Fig. 4, in order that the slide may he re
polished re?ector surface) and between such ceived in grooves located in the inner faces
re?ector and the negative I interpose a of guides 22 which project from one side of
screen adapted to correct inequalities in the the enlarger frame 23. At its opposite end 85
light rays which otherwise would pass the enlarger frame 23 is provided with a
through the negative. By the term non foot 24 which may rest on the face of the
ditlusing re?ector is meant a re?ector hav slide 20. .
ing a highly polished re?ecting surface. A Passing through both guides 22 prefer
re?ector of this type re?ects more light than ably close to the slide 20 is a bolt 25 and on
it intercepts or absorbs. I mount such an the screw-threaded end of such bolt is
enlarger upon a two-part support which mounted a nut 26 of‘ a type adapted to be
when both support-parts are used holds the tightened by hand. The nut 26 does not
enlarger in a vertical position to project bear directly against the adjacent guide 22,
vertically and one part of which may be but bears against a part 27 which is affixed 95
40 employed to hold the enlarger in a hori to the outer side of such guide. The adja~
zontal position to project horizontally. cent faces of the nut 26 and the part 27 are
The accompanying drawing illustrates my provided with helical cam surfaces opposite
invention: Fig. l is a side elevation of my in inclination to the threads of the bolt 25
enlarger in partial section showing the en and nut 26 and having a relatively greater 100
larger in its vertical. position; Fig. 2 is a pitch than such threads. This construction
horizontal section on the line 2—2 of Fig. facilitates the adjustment of the enlarger
1; Fig. 3 is a fragmental vertical section on proper on the slide 20, for the nut 26 can be
the line 3 3 of Fig. 1; Fig. 4 is afrag operated to clam or unclamp the guides 22
mental horizontal section on the line 4—4 on the slide 20 with but a fraction of a turn 105
(EU of Fig. 1; Fig. 5 is a plan view of the screen of the nut.
which is interposed between the negative Rigid with theframe 23 and conveniently
and the re?ector; Fig. 6 is a somewhat dia forming a part thereof is a negative-holder
orammatic elevation illustrating the path of support 30 which is provided with a central
light rays through my enlarger; and Fig. 7 opening for the passage of light. On oppo 110
55 is a side elevation of my enlarger in use in a site sides of this central opening are grooves
horizontal position. for the reception of the negative holder 31
 1,088,928
is adapted to receive and support the through a slot. 65 in the tube 60 into the
negative 32. Near its top, the support 30 base 61.
is provided with a circular ?ange 33, ‘the top Desirably, air admission openings 70 are
edge of which is rabbetted to receive the provided in the ?ange 33. To prevent light
lower ed of the re?ector. 35. _ from emerging from such openings, they are
A lon tudinally extending guide plate 40 covered with hoods 71, conveniently made
is a?ixe to the enlarger frame 23 1n any of -metal and so arranged as to permit ad
suitable manner. The edges of 'the guide mission of air into the interior of the re
plate 40 are received in parallel grooves in ?ector but to form a light trap to prevent
10 'des 41 carried bya lens-board support 42. direct rays of light‘from passing through
bolt 43 extends between the guides 41 and the holes 70. The air admitted through the
is provided with a knurled clamping nut 44 holes 70 passes'out through one or more
which when tightened serves to hold the longitudinal passages or holes 72in the light
lens-board support 42 stationary relative to socket base ‘61. To prevent direct rays of
15 the enlarger frame. Preferably, a shaft 45 light from emerging through the holes 72 80
‘rovided with a knurled-operating knob 46 such holes are also covered with a light trap
is rotatably mounted in the 41 and at which will allow the free passage of air.
an intermediate point is provided with a This light trap is preferably in the form of
pinion 47 which meshes with a rack 48 car a ?ange 73 on the protruding end of the base
20 ried by the guide plate 40. The lens-board 61 an vis slightly larger in diameter than 85
sup ort 42 may be adjusted longitudinally the diameter of the tube 60, so that it will
of t e enlarger frame y rotating the knob also form a light trap for any rays emerg
46; and when the desired position of ad ing between the wall of the tube 60 and the
justment is reached, the lens-board support. base 61. This arrangement permits a circu
25 42 may be clamped in such position by lation of air through ,the re?ector‘ and 90
means of the nut 44. _ around the light bulb and thus keeps the
The lens-board support 42 has a central re?ector, light bulb, and adjacent parts at
opening for tllel'GOBPtlOD of a lens-board 50 a low temperature.
which may conveniently be held in place in The light bulb 63 is a frosted, etched, or
30 the support 42 by means of suitable clips 51. coated bulb the, surface of which acts to 95
In the center of the lens-board 50'I provide diffuse emitted light. The use of such a bulb
a lens-mounting 52 which contains any suit with a nonédiifusing re?ector produces sub
able lens system 53. Extending between the stantially even illumination of the-negative
two supports 30 and 42 is the collapsible belr and projected ?eld except for a cent-rally
86 lows 54. _ . located spot which is caused by the direct
The re?ector 35 is of ellipsoidal shape rays of light from the bulb.‘ To prevent this
lot
'and its interior surface is‘highly polished over-illumination of the central portion I
so that it will re?ect light-rays with substan interpose between the re?ector and the nega
tially no diffusion. Such a re?ector is con tive a screen 75 which is conveniently a piece
veniently and economically stam ed or spun of glass held in place by cleats 76 on the
from some suitable metal, after w ich the in support frame 30. This glass screen 75 is'
terior' surface‘ is' silvered and polished to preferably made by sand blasting or blast
provide the desired non-diffusing re?ecting ing with ?ne particles of hardened steel.
surface. The re?ecting surface of the in The entire surface of this glass is lightly
45 terior of the re?ector is preferably protected blasted or grained, giving it a substantially ll
from tarnish by means of a thin coating of even blasting except for a round spot- 77 in
clear transparent lacquer. The lower, or the center of the screen which spot has a -
free, edge of the re?ector is rolled to form rougher and much heavier blasted surface
a reinforcing bead as is clear from Figs. 1 than the remainder'of the screen. In cer
and 6. The re?ector may be held in place tain instances it may be desired to make the ll?
on the ?ange 33 by a pin 55 mounted in the surface of the screen 75 slightly less rough
?ange 33 in position to project outward near its edges and the corners than it is in
through a hole. in the re?ector; 35 and by a the vicinity of the spot 77; but even if such
leaf spring 56 carried by the enlarger frame is the case a well de?ned spot 77 in the cen
23 and adapted to engage the head at the ter of the screen is desirable. '
edge of the re?ector. The extra illumination of the negative and
Projecting axially upward from the el projected ?eld can be eliminated by darken
lipsoidal re?ector 35 is a cylindrical tube 60 ing or making more opaque the lower part
which receives a base 61 for a light-socket of the light bulb; but this is not as desirable
62. The base 61 is desirably slidable in the as ‘the spotted glass screen. Any method 12
tube 60 in order to vary the longitudinal po which would screen or diffuse the central or
sition of light bulb 63 which is mounted in direct rays of light would‘ accomplish the
the socket 62. To retain the base 61 in any desired result but I have found the'blasted
desired position of longitudinal adjustment, glass to be practical, economical, and per
a screw 64 may be providedwliich passes manent. ' ' ' 13
 1,688,988
The diameter of the spot 77 is substan more efficient than one which diffuses the
tially equal to that of the image of the light~ light rays incident u on it; as with a. dif
bulb, and hence prevents excessive illumina fusing re?ector a re atively large propor
tion of the negative in the center thereof. tion of light falling on the negative strikes
This result is accomplished in two ways.. at such an .angle that it is lost on the black
The heavier graining of the screen 75 within 70
the borders of the spot 77 renders such spot ened inner surface of the bellows. In addi
tion the total amount of ii ht re?ected from
more opaque than 15 the remainder of the a diffusing surface is less t an that re?ected
screen; and in addition, this heavier grain from a highly polished surface.
10 ing causes a larger pro ortio'n of the light In an enlarger of the ty e I have de
incident upon the spot 7 to be diffused at 75
such an an le that it strikes and‘ is absorbed
scribed the frosted light bulb has another
by the blue ened interior of the enlarger. advantage aside from, preventing ill effects
from imperfections in the re?ector.
The ground glass screen 75 is mounted With the light source of considerable size,
sufficiently far above the ne ative 32 so that such as a frosted bulb, the distance between 80
the grain of the ground gass will not be the negative and lens can be varied through
seen in the projected image of the negative. a_w1der range to produce enlargements of
To avoid shadows on the negative it is different sizes wit out varying materially
necessary that the central opening in the the intensity of the projected ?eld. If a
support 30 be of such dimensions at all light source of small area is employed with
points that its walls will not intercept any a polished re?ector there will be one position
useful light rays which would otherwise fall of the .lens at which substantially all the
on the negatiie. As the useful rays falling re?ected light rays will pass through the
on the negative near its edges are at an a - lens. For this one position of‘the lens the
25 preciable angle to the axis of the ‘lig it enlarger would be very efficient, but if the 90
system of the enlarger, I prefer to taper the lens were moved from this position a marked
walls of the opening through the support falling off in the intensity of the projected
30, as in this way I make the opening of ?eld would occur. This constitutes a real
sufficient size at all points so that intercep defect in an enlarger, for in operation ‘the
30 tion of useful light rays is eliminated, and I axial position of the lens must be varied in 05
accomplish this result without making the producing enlargements of different sizes,
bottom end of the opening through the and it is desirable that the adjustment have
frame 30 excessively large. This feature of no effect on the intensity of the projected
my invention becomes more important when ?eld. This defect can be partially althou h
35 the support 30 is relatively thick axially of not entirely overcome by readjustin t e 100
the enlarger or when the useful light rays at light source whenever the lens is move , but
the negative margin have a relatively large this is impracticable and troublesome. When
angle with respect to the axis. _ the light-source is of considerable size there
If enlargements are desired of a size which is no position of the lens in which all the
40 cannot be readily attained with the enlarger re?ected light passes through it. If the lens 105
in the vertical position shown in Fig. 1, the is moved along the axis, some of the light
enlarger and stand 11 can be removed from rays which previously passed through the
the base 10 and placed in a horizontal posi lens will now miss it and others-which pre
tion as illustrated in Fig. 7. Any suitable viously‘ missed the lens will pass through it.
frame or easel 80 inay be then provided for Thus, without the necessity for adjusting 110
the carrying of the sensitized paper. the light, the lens can be moved axially
The use of the frosted li ht bulb 63 in without varying materially the intensity of
conjunction with the non-di using re?ector the projected ?eld.
35 produces substantially even illumlnation The distance through which the lens may
50 and heating of the negative, particularly be moved without affecting the intensity of 115
when the screen 75 is employed. It is im the projected ?eld varies with the axial posi
practical and expensive to attempt to pro~ tion of the light-source as well as with its
diice a perfect re?ector 35; and the spinning size. This is so because the greater the dis
process which appears to be the most eco tance between the light source and a point
55
nomical method of making such re?ector in in the re?ector the smaller will be the angles 120
evitably leaves in the re?ector irregularities of convergence and divergence respectively
in the form of ring-shaped ridges in the of the pencils of rays incident upon and
re?ecting surface. If a clear light bulb re?ected from such point, and the more
were used in place of the diffusing bulb 63, nearly will such re?ected rays cross the re-_
60 these inequalities in the re?ecting surface ?ector axis in a common point. I have '
would be evident in the illuminated ?eld; found that the best results can be obtained
but when a frosted bulb is used these in with my enlarger by ‘constructing it so that
equalities in the illumination of the ?eld the light bulb ?lament is substantially in
disappear. I have found that a re?ector one focus of the ellipsoidal re?ector and the
having a non-diffusing re?ecting surface is lens is in or near the other focus.
 1,638,828
In the above description of my invention, lens, of a light source, a re?ector'for said
I have used the expression “light source” to light source, said re?ector having a non
indicate the whole light bulb such as the ditfusing re?ecting surface, and a light
frosted or etched li lit-bulb which I prefer transmitting screen mounted in position to
to employ. Actual y- of course, the light screen direct andv re?ected li ht rays from 7.0
said light source before they all on a nega
emanates from the ?lament if a ?lament tive in said negative holder, said screen hav
type bulb is used, but the light is so diffused ing a portion which transmits to the lens a
at the glass of the bulb that the bulb_beco_mes proportion of the light falling upon it
for all practical purposes the effective light smaller than that proportion of the light 75
source. In the claims, also, I have used the falling on the remainder of the screen and
expression “light source” to designate ge
nerically any actual or effective source of transmitted
5. In a
to the ‘lens.
photographic enlarger,
‘
the combi
light. Where it becomes necessary in the nation with the usual negative holder and
claims to distinguish between the actual ele lens, of an electric light bulb having a light 80
ment from which light originally emanates diffusing surface, a re?ector for said light
and the diffusing means (theglass of the bulb, and a light-transmitting screen mount
light bulb) which diffuses the light before 1t ed in position to screen direct and re?ected
strikes the reflector, I have used the term light rays from said bulb before they fall
“light element” to designate the original on a negative in said negative holder, said
20 light-producer, such as the ?lament or its screen having a portion which transmits to
equivalent. the lens a proportion of the light falling
I claim as my invention:
1. In a photographic enlarger, the com upon light
it smaller than that proportion of the
falling on the remainder of the screen
bination with the usual negative holder and and transmitted to the lens.
lens, of an electric light bulb having a light 6. In a photographic enlarger, the combi
diffusing surface, an ellipsoidal reflbctor for nation with the usual negatlve holder and
said light bulb, said re?ector having a non lens, of a light source, a re?ector for said
di?'using re?ecting surface, and a diffusing light source, and a light-transmitting screen
glass screen mounted in position to intercept mounted in position to screen direct and re 95'
30 direct and re?ected light rays from said bulb flected light rays from said light source be~
before they pass through a negative in said fore they fall on a negative in said negative
negative holder, said glass screen having a holder, said screen having a portion which
central spot within the borders of which the transmits to the lens a proportion of the
graining of the glass is appreciably heavier light falling upon it smaller than that pro
36 than on the remainder of the screen.
2. In a photographic enlarger, the combi portion
of the
of the light falling on the remainder
screen and transmitted to the lens.
nation with the usual negative holder and 7. In a photographic enlarger, the combi
lens, of an electric light bulb having a nation with the usual negative holder and
light-diffusing surface, an ellipsoidal re lens, of a source of light, a re?ector there 105
40 ?ector for said light bulb, said re?ector
having a non-diffusing re?ecting surface, and for, and a light-transmitting screen mounted
in position to screen light rays falling on a.
a light-transmitting screen mounted in posi negative
tion to intercept direct and re?ected light having a in said negative holder, said screen
portion which transmits to the lens
rays from said bulb before they pass through a proportion of the light falling upon it
a negative in said negative holder, said
screen having a portion which transmits to smaller than that proportion of the light
the lens a proportion of the light falling falling on the remainder of the screen and
upon it smaller ‘than that proportion of the transmitted to the lens.
light falling on the remainder of the screen 8. In combination with a photographic
enlarger, a stand therefor, said stand having 115
and transmitted to the lens. a longitudinal slide on which said enlarger
3. In a photographic enlarger, the com
bination with the usual negative holder and is slidable, said enlarger having two guides
lens, of a light source, an ellipsoidal re arranged to receive said slide between them,
?ector for said light source, sald re?ector a clamping bolt extending between said mem
having a non-diffusing re?ecting surface, bers and through and beyond one of them, a 120
and a diffusing glass screen mounted in posi nut screw-threadedly mounted on said bolt,
and a part carried by
tion to intercept direct and re?ected light said nut, said nut and said the guide adjacent
part having, en
rays from said light source before they fall gaging helical surfaces opposite
on a negative in said negative holder, said tion to the screw-threads of said nut in inclina 125
glass screen having a central s ot within and bolt.
(it)
the borders of which the grainmg of the bination with the usual negative holdercom
9. In a photographic enlarger, the
and
glass is appreciably heavier than on the re lens, of an electric light bulb having a light
mainder of the screen.
4. In a photographic enlarger, the combi diffusing surface,
bulb,
an ellipsoidal re?ector for
said re?ector having a non 13(
nation with the usual negative holder and said light
 1,688,228
diffusing re?ecting surface, and a diffusing 15. In combination with a photographic
glass screen mounted in position between
enlarger having the usual light source, nega—
the negative holder and light bulb, so that tive
light rays from said light bulb must pass screen older, and lens, a light-transmitting
through said screen before'passing through and negativeinterposed between the light-source
holder, said screen having a 70
the negative, said diffusing glass screen hav central area adapted
ing a central spot which intercepts more proportion of light-rays to intercept a larger
light and diffuses to a greater degree the than is intercepted by the incident
remainder
upon 11;
of the
light rays incident upon it than does the re
10 mainder of the ?eld of said diffusing glass. screen, said central area being substantially
10. In a photographic enlarger, the com concentric
16. In a
with the axis of the enlarger.
photographic enlarger, the com
75
bination with the usual negative holder and bination with
lens, of a light source, an ellipsoidal re?ec lens, of'a lighttheelement,
usual negative holder and
a re?ector for said
tor for said i ht source, said re?ector hav light element, said re?ector
ing a non-di using re?ecting surface, and diffusing re?ecting surface, havin and
a non
ight-dif
a diffusing glass screen mounted in position fusing means between said light element and
between the negative holder and light source, said re?ector to diffuse light rays before the
so that light rays from said light source must are re?ected by said re?ector to ass throng
pass through 'said screen before passing
20 through the negative, said diffusing glass a negative in the ne ative hol er. 1
screen having a central spot which intercepts 17. In a photograp ic enlarger, a negative
more light and di?'uses to a greater degree holder, a lens, a ‘light bulb having a light
diffusing surface, a reflector for said vlight
the light rays incident upon it than does the bulb, the light-diffusing surface of said
remainder of the ?eld of said diffusing glass. light bulb
25 11. In a photographic enlarger, the com being located to intercept light
bination with the usual negative holder and rays from the bulb to the re?ector, said re
lens, of a light source, a re?ector for said ?ector having a non-diffusing re?ecting sur
light source, said re?ector having a non-dif— face and being arran ed to re?ect rays of
light from the light ulb through a nega
fusing re?ecting surface, and a_ diffusing tive
30 glass screen mounted in position between the throughin the negative holder and thence
the lens. 95
negative holder and light source, so that 18. In a photographic enlar er, the com
light rays from said light source must pass bination of a source of diffuse light, a non
through said screen before passing through diffusing ellipsoidal re?ector for the dif
the negative, said diffusing glass screen hav fused-light source, a lens through which said
ing a central spot which intercepts more re?ector directs light from
light and diffuses to a greater degree the light source, and means for said diffused
supporting a
100
light rays incident upon it than does the re transparent picture between said diffused~
mainder :of the ?eld of said diffusing glass. light source and said lens and between the
12. In' a photographic enlarger, the com re?ector and the focus thereof distant from
40 bination of a lens, a negative holder, a light the light source, so that an image of said
element, a non-diffusing re?ector therefor,
and means for diffusing light-rays emitted picture may be produced on the other side
of the lens.
from said light element before they strike 19. In a photographic enlarger, the com
the re?ector.
45 13. In a photographic enlarger, the com element, of
bination means for supporting a light
a non-diffusing concave re?ector Ht;
bination of ‘a lens, a negative holder, a light for the light element, a lens through which
element, a non-diffusing re?ector therefor, said re?ector directs light from said light
means for diffusing light-rays emitted from element, means for supporting a transpar
said light element before they strike the re ent picture between said light element and
50 ?ector, and additional means for diffusing
light rays from said light element before said lens, so that an image of said picture 115
they pass through a ne ative in said nega may be produced on the other side of the
tive holder and thence t rough the lens. lens, and means between the light element
14. In combination with a. photographic the and the re?ector for diffusing the light from
55 light element. _
enlarger, a stand therefor, lateral projections 20. In a photographic enlarger, the com
on said stand adapted to serve as legs to bination of means for supporting a. light 120
hold the enlarger in a horizontal position, a
base having a foot adapted to be secured to element, a non-diffusin concave re?ector
for the light element, alens through which
60
a horizontal surface, said base also having said re?ector directs light from said light
near its top a horizontal projection which element, means for supporting a transparent 125
projects beyond the limits of said foot, and picture between said light element and said
means for securing one of the lateral pro lens, so that an image of said picture may
jections on said stand to the horizontal pro be produced on the other side of the lens,
jection on said base to hold the enlarger in light-diffusing means located between the
vertical position. light element and the re?ector, and addi 130
 I 1,eaa,aaa

said negative holder being between the light

tional light-diffusing means located between element and the lens on the axis of the re
the re?ector and the lens. ?ector and substantially perpendicular to
21. In a photographic enlarger, the com such axis, so that both direct and re?ected
bination of the usual negative holder and rays of light pass through the negative
lens, a light element, a concave re?ector hav holder and thence through ‘the lens, and
ing a non-di?using re?ecting surface ar light-screenin means for screening the 55
ranged to re?ect rays from said light ele
ment through the negative holder and lens, light rays w ich pass from the light ele
the opening of the negative »
anda light-di?using enclosure for said light holder.through
ment
and thence through the lens, said 1i ght
element, said enclosure being arranged to
di?use light emitted from said light ele screemng
mltting
means havin greater light-trans
capacity for-t e light directed to
ment before it falls on said re?ector, so that ward the outer part 9f said opening than
for a given position of the light element for that directed toward the central ortion
relative to the re?ector the size of said en
closure determines the apical an le of the of and
said opening, so that the combine direct
re?ected rays which pa§ through the
cones of light incident upon an .re?ected negatlve holder when it is empty and thence
froma point in said re?ector.
22. In a photographic enlarger, the com tributed overlens
through the
the
are substantially evenly dis
opening through the nega
bination of the usual negative holder and
lens, a light element, a concave re?ector hav tive holder.
ing a non-diffusing re?ecting surface ar v_25._In a photographic enlarger, the com 70
ranged to re?ect rays-from said light ele bination-with
lens, of a
the usual negative holder and
source of di?used light, and a
ment through the negative holder. and lens, concave re?ector having a non-di?using re
and a light-transmitting enclosure in which ?ecting surface and having its larger end
said light element is located and at points larger in diameter than the greatest dimen
on 'a surface of which enclosure light from sion of the opening of the negative holder; 75
said light element radiates so that the light said light source being located between said
element and enclosure together serve as a re?ector and said negative holder, and said
source of diffused light, whereby for ‘a given ne ative holder being located between said
position of the light element relative to the hg t source and the lens, so that the apical
re?ector the size of said enclosure deter an les of the two cones of light from the
mines the apical angle of the cones of light lig t sour e respectively incident upon and
incident upon and re?ected from a point in re?ected rom a point in said re?ector de
said re?ector. ' pend upon the size of the light source and
23. A photographic enlarger as set forth vary directly with such size; and said light
in claim 35, with the addition that the en source, re?ector, negative holder, and lens
closure for said light element is of size su?i being so arranged that light rays from said
cient that, a cone of light re?ected from a light source falling upon said non-di?usin
given point in said re?ector will have in the re?ecting surface are convergently re?ecte
vicinity of the lens a diameter greater than toward an area of greatest concentration 10
that of the lens in order that axial adjust cated on the opposite side of said negative U
ment of the lens may be accomplished with holder from said re?ector.
out producing a material variation in the In witness whereof, I have hereunto set
strength of the projected ?eld. my hand at Indianapolis, Indiana, this 6th
45 24. In a photographic enlarger, the com day of April, A. D. one thousand nine hun
bination with the usual negative holder and dred andtwenty six.
lens, of a non-di?using concave re?ector, a ‘ ELWOOD C. ROGERS.
light element associated with said re?ector,
 .CERTIFICATE OF CORRECTION.

Patent No. 1,633,228. Granted June 21, 1927, to

ELWOOD C. ROGERS.

It is hereby certified that error appears in the printed specification of the

above numbered patent requiring correction as follows: Page 6, line 36, claim
23. for the numeral "35" read "22“; and that the said Letters Patent should be
read with this correction therein that the same may conform to the record of
the’case in the Patent Office.
Signed and sealed this 2nd day of August, A. D. 1927.

M. J. Moore,
Seal. Acting Commissioner of Patents.