Aug. 30, 1949. L. L. WEISGLASS 2,480,101 ILLUMINATING SYSTEM FOR PHOTOGRAPHIC ENLARGERS Filed Aug. 9, 1945 5 Sheets-Sheet

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18 N.242a 4\ 4. \ / , \ / \ / Louis A. Weisgass \ INVENTOR, y 2S, BY k - A. fe Ziff/1NSSS Sages "Rallies (44a. 2/-SSS A 77 oANAY. Aug. 30, 1949. L. L. WEISGLASS 2,480,101 ILLUMINATING SYSTEM FOR PHOTOGRAPHIC ENLARGERS Filed Aug. 9, 1945 5 Sheets-Sheet 4

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Louis L. Weisg/ass INVENTOR, "fluiz; Wa. A 770ANAEY. Aug. 30, 1949. L. L. WEISGLASS 2,480,101 ILLUMINATING SYSTEM FOR PHOTOGRAPHIC ENLARGERS Filed Aug. 9, 1945 5 Sheets-Sheet 5

Louis Weisg/ass INVENTOR. " Kuti, S.W.e4a. Artorney Patented Aug. 30, 1949 2480,101

UNITED STATES PATENT of FICE 2,480,101 LLUMINATING SYSTEM FOR, PBOO GRAPHC ENLARGERS Louis L. Weisglass, New York, N. Y., assignor, by mesne assignments, to Simmon Brothers, Inc., Long Island City, N. Y., a corporation of New York Application August 9, 1945, Serial No. 609,873 1. Claim. (C. 88-24) This invention pertains to an improved illu together with a specular reflector of at least minating system for photographic enlargers. It partly ellipsoidal shape. is based on the following considerations: A well designed spotlight of this type will con The design of the most successful type of photo centrate approximately 70% of the light emitted graphic enlarger is based on two premises: by the lamp on a selected spot of the diffuse re 1. It is necessary to use diffused light. This flector. A diffuse reflector built from a well is due to the peculiar light scattering property chosen white opaque material will reflect as much of the photographic emulsion, commonly known as 90% or more of this light. The efficiency of as the "Callier effect'; the apparent contrast of the system will then be .70X.90=.63 or 63%. a photographic image depends upon the type of O This is almost four times as high as the 16.6% light to which it is exposed, specular or entirely computed for the conventional System using an undiffused light forming images of extreme and opal lamp. These figures have been verified by unusable contrast, but diffused light producing actual experiments with a very good degree of SOfter prints. approximation. 2. It is desirable to use condensers unless one 15 This computation shows that the perform wants to be limited to an extremely low level of ance of my system is due to the utilization of the light intensity. superior light reflecting properties of certain These two conditions were satisfied in the past white opaque substances. It is a scientific fact by the customary arrangement of a diffused that these substances reflect light better than source of light represented by an incandescent 20 specular reflectors, i.e., mirrors. lamp with an opal vessel positioned substantially In addition to this superior efficiency, there is in the focal point of a condenser. This arrange now no longer any limitation upon the wattage ment has the following disadvantages: that can be utilized in an enlarger of this type. a. Half of the light of the lamp is emitted rear I have successfully built an enlarger with a dif wardly and lost and cannot be recovered by the fuse white reflector according to the principles of use of reflectors since the lamp is so large that this invention which was illuminated by two spot the reflected light would have to pass the lamp lights of 200 watt each, Compared to a conven again. The opal vessel then absorbs 23 of the tional enlarger with an input of 75 watt, this en remaining light. As a result, approximately only larger had a light output approximately 16 to 20 30 times as large in spite of the fact that the Watt As of A=% or 16.6% of the light can be utilized. age was only slightly more than five times as b. It is impossible to obtain higher levels of high. intensity by increasing the Wattage of the lamp. The broad principle of an illuminating system A condenser system is So adjusted that an image of this type has been disclosed in my co-pending of the lamp is projected into the pupil of the 35 application, Serial No. 577,216, now abandoned. enlarging lens. It is desirable that this image The object of this present invention is to pro be as large or even slightly larger than the pupil vide improved means for a more nearly uniform of the lens, but it should not be appreciably illumination of the aforementioned diffusely re larger, since light which falls outside of the mar flecting surface which is disposed substantially gins of the lens is obviously lost. This means 40 in the focal point of a condenser. A further ob that the size of the lamp should not exceed cer ject of this invention is improved means to COn tain limits, and this, in turn, imposes a very def trol the intensity of the illumination. A fur nite limitation upon the wattage which can be ther object of this invention is to provide an im used in such a system. Broadly speaking, it can proved material for said reflecting body which is not be much larger than 150 watt. 45 superior to the body of magnesium carbonate These two limitations are overcome in my in which has been described in my prior applica vention. Instead of the aforementioned lamp tion, Serial No. 577,216. with an opal glass vessel, I use a diffuse reflector The first object, i. e., a more nearly uniforn made from white opaque material substantially in illumination of the diffuse reflector, I obtain by a the focal point of the condenser. This reflector 50 combination of three means, namely, first by is, in turn, illuminated by a suitable spotlight, or providing a spotlight with a specular reflector of by several spotlights. These spotlights may be peculiar shape composed partly of a paraboloid constructed in many ways, but I prefer a suitable and partly of an ellipsoid body of rotation, sec Source of light such as an incandescent lamp, of ond, by using a plurality of these spotlights, and the type used in lantern slide or movie projectors, 55 third, by having the axis of these spotlights 2,480,101 3 4. slightly offset in different directions with respect Fig. 6 is a horizontal sectional view along the to the optical axis of the enlarger. plane of line 8-6 in Fig. 5. The second object, i.e., control of the intensity Like characters of reference denote similar of the illumination, is obtained by arranging the parts throughout the several views and the foll diffuse reflector in a plane perpendicular to the lowing specification. optical axis of the condenser and the enlarger The enlarger consists of three principal parts, lens and by providing means to shift this diffuse a base, an upright column and a projector as reflector in the direction of said optical axis. sembly. This, in effect, defocuses the reflector, both with The base 0 is preferably made from plywood respect to the spotlight and with respect to the 0. or the like. On this base is fastened a bracket condenser. A very efficient control of the illumi l, preferably made from cast iron or aluminum nation is provided thereby, and it is possible to which Supports two U-channels 2. These control the illumination from its highest inten channels are arranged either vertically or, pref sity, 100%, to a value as low as 4% thereof. erably, under a slight angle as shown. Slidably This light intensity control is so simple that 5 mounted on this vertical or nearly vertical co it lends itself very easily to an automatic arrange unn is the projector assembly. This projector ment, whereby the position of the diffusely re assembly consists of a supporting carriage, a fo flecting plate and thereby the light intensity, cusing assembly with an enlarging lens, and a may be controlled by a cam in dependence of lamphousing. the distance between the projector assembly and 20 The carriage consists of two steel plates 3 the easel which supports the bromide paper. The which are bolted together by four bolts 4. These cam used for this purpose may have any desired bolts serve at the same time as shafts for rollers configuration and the light output may follow 5 by means of which the carriage slides with almost any law, but the most useful arrangement a Small amount of friction on the aforemen is the one in which the intensity of the light in 25 tioned channels 2. pinging upon a unit area of the bromide paper The steel plates 3 have a configuration clear supported on the easel is kept constant and in ly shown in Fig. 2. Each steel plate has a lug dependent of the aforementioned distance be 6 adapted to Support the lamphousing. A pro tween projector and easel. In this manner, the jection 7 is provided which supports a film stage exposure time for any given negative becomes in 30 8 which, of course, has an aperture of the de dependent of the magnification ratio. This sim sired size. The negative, preferably supported by pifies the technique of making enlargements one of the well known types of holders is, during considerably and is a great Convenience to the operation, placed on this apertured film stage Operator. 8. A film holder suitable for this purpose is, The third object of the invention is to provide 35 for example, shown in either of Patents No. a better material for said diffusely reflecting 2,222,185 issued November 19, 1940, and 2,239,760 plate. The magnesium carbonate used hereto issued April 29, 1941. fore is a very efficient reflector, but it has very A lens carrier 9 is supported by at least one poor mechanical properties, is a poor conductor or, preferably, two guide rods 2G and carries the of heat, and decomposes into powder quite read 40 enlarging lens 2. The guide rods 2 run in ily. I have found that for all practical purposes, bearings 22. A focusing device comprising, for a metal plate coated with vitreous enamel is just example, a rack and pinion movement or the as efficient, but has much superior mechanical like, not shown in detail, permits the operator properties, is a good heat conductor, and is much to adjust the position of guide rods 20 and there more durable. Certain safeguards have to be pro 45 with of lens support 9 and lens 2 by simply vided to eliminate the effect of the surface gloss turning hand wheel 23. which such vitreous enamel coating has. This The enlarger as described up to this point is can be done by either sand blasting it, or by ar quite conventional, and does not depart appre ranging the plate under such an angle that only ciably from other well known designs. the diffuse reflection, which constitutes approxi 50 The lamphousing consists of the following mately 90% of the total light, reaches the con parts: A main housing 30, preferably an alumi denser, but that the remaining specularly re num casting or the like, a condenser with a con flected light, which usually does not exceed 10% denser housing 3 and condenser lenses 32, a dif of the total light, becomes reflected under such fuse reflector plate 33 supported by a rod 34 and 55 movable by means of a rack 35 and a pinion 36, an angle that it will not reach the condenser of the entire reflector assembly being supported by the enlarger. More specifically, this means that a housing 37, and two spotlights adapted to ill the angle between the central ray of the light luminate this reflector plate. These spotlights emitted from the spotlight and the optical axis comprise a specular reflector 40, a lamp 6 and of the condenser must be less than twice as large means to adjust the position of the lamp with than the angle between said central ray, and a respect to the specular reflector. These means straight line perpendicular to said diffuse white comprise a casting 62 which is brazed or other reflector. L wise fastened to the reflector 60, and a flange 42 In the accompanying drawings, Fig. 1 is a adapted to receive the lamp socket 44 of lamp front elevational view of a photographic enlarger 65 f. As can be seen, the flange 43 is fastened to embodying the principles of my invention; 42 by means of Small screws. The holes for these Fig.2 is a side view of the same; Screws are made larger than strictly necessary Fig. 3 is a vertical sectional view along the So that it becomes possible to shift flange 43 plane of line 3-3 in Fig. 2, drawn to a larger slightly with respect to the specular reflector 40. scale; 70 It is also possible to loosen set screw 45 and Fig. 4 is a horizontal sectional view along the thereby change the longitudinal position of the plane of line 4-4 in Fig. 3; lamp socket 44 with respect to flange 43. The Fig. 5 is a side view, partly in section, of a combination of these two movements makes a modified projector assembly adapted for auto complete adjustment of the filament of the lamp matic intensity control; and 75 with respect to the specular reflector 40 possible. 2,480,101 The shape of the specular reflector can best be tioned above, it may be found advantageous to seen in Fig. 4. It consists of a rear part 50 which use only one spotlight in small size enlargers or is a paraboloid body of rotation, a front part in types where expense is paramount, I, there which is an ellipsoid body of rotation and a short fore, do not wish to limit the scope of the inven cylindrical part 52 which connects the two. Con tion to two or more lights but wish to include also tinuations of the parabola or ellipse, respectively, the use of One spotlight only. which form the two parts are shown in dotted Referring to Fig. 2, a handwheel 60 is pro lines. The lamp is so disposed that it is sub vided by means of which the operator through stantially in the focal point of the parabola and rack 6 and pinion 35 can raise or lower reflector in one of the focal points of the ellipse and the plate 83. In the lowest position the reflector plate diffuse reflector 33 is disposed substantially in is substantially in the focal point of condensers the other focal point of the ellipse. 32 and it is also substantially in the focal point As can be seen in Fig. 4, the center lines of the of the two spotlights. By raising it, it will assume, two spotlights are offset with respec to the opti for example, the position shown in Fig. 3 in dot cal axis of the enlarger, but in different direc 15 ted lines. In this position the plate is consider tions. ably out of focus both with respect to the con In order to obtain the most intense and the densers 32 and the spotlights and, therefore, the most nearly uniform illumination on the easel, amount of light reaching the condenser is con it is necessary to provide an illuminated spot on siderably smaller. The defocusing with respect to the plate 33 which is of approximately 1% to 2' 20 the spotlights is far more important than the diameter, depending upon the focal length and defocusing with respect to the condenser lens and diaphragm opening of the enlarging lens, and to the extremely large variation of the light obtain illuminate this spot with a substantially uniform able with relatively small movements of the re light intensity per unit area. Failure to do so flector is due to this fact. I have found that by produces objectionable patterns of more Or less 25 raising the plate for a distance of approximately bright spots on the easel, particularly when the 2', on an enlarger adapted for 4 x 5' negatives, lens is being stopped down. It is rather difficult for instance, I can control the light intensity from to fulfill these conditions since all incandescent its full value when the plate is in its extreme low lamps are quite different from real point Sources position to a low intensity which is only ap of light and since they all have filaments with 30 proximately 4% of the aforementioned full in appreciable physical dimensions. These fla tensity. ments are arranged in a certain pattern and un AS can be seen, these means to control the light less precautions are taken, these patterns will intensity are of extreme mechanical simplicity be discernible on plate 33 and also, at least to and they have the added advantage that the color some extent, on the easel supporting the bromide 5 of the light, i. e., the color temperature of the paper. In order to eliminate these objectionable light is not affected. This device is distinguished filament patterns without the use of light ab favorably in this respect from an electric rheo sorbing diffusing glass or the like, I resort to stat. Due to this mechanical simplicity, it be three expedients, singly or in combination: comes now possible to devise very simple auto First, I have found that a specular spotlight matic means by which the light intensity of the reflector with a partly ellipsoidal and party enlarger may be rendered independent of the dis paraboloid shape delivers a more nearly uniform ance of the projector, or more particularly, of spot than the purely ellipsoidal reflector used the film stage of that projector from the bromide heretofore. paper Supported by the easel or the base plate O. Second, I use, preferably, more than one spot 45 A device of this character is shown in Figs. 5 and light. It will be clear that with one spotlight 6. The reflector plate 33 in this case is not sup only the entire optical system becomes unsyrin ported by the rack and pinion movement shown metrical and it is almost unavoidable that the heretofore, but by two levers 70. These two levers light distribution on the easel also shows a slight, are Supported, respectively, on one end by shafts but noticeable lack of symmetry, i. e., one side 50 and 2 and on the other end by shafts 73 and receives slightly more light than the other. The 74. Shafts 3 and 74 engage two lugs 75 which, symmetry of the optical System can be restored in turn. Support the reflector plate 33. The two by using at least two, but if necessary, three or shafts if and 72 are supported by a housing 76 for SnotlightS. which supports the entire reflector assembly. Third, these spotlights are preferably disposed 55 The lower of the two levers TO is attached to shaft in the manner shown in Fig. 4, i. e., their cen 2, as stated before, and a lever TT is attached to ter lines are slightly offset with respect to the the Same shaft. This lever terminates in a cam optical axis of the enlarger, but in different di following roller 78 which is in operative engage rections. The most common type of projecting ment with a cam 79. This cam is fastened to one lamp has two flaments and, therefore, projects 60 of the steel channels 2. a pattern on plate 33 consisting of two elongated The function of the device will be quite bright spots. By using two spotlights in this clear from Fig. 5. When the projector as offset manner the relatively dark portion be Sembly moves upwards the enlarging ratio in tween the bright spots of one spotlight will be creases and, therefore, in an ordinary enlarger covered by one of the bright spots of the other the light in the easel plane will decrease, roughly, spotlight and vice versa. In this manner, a in inverse proportion to the square of the mag brightly illuminated spot can be formed on plate nification ratio. . With this enlarger, however, 33 which has the required dimensions and which the cam following roller 78 will follow the con is illuminated with substantially unifom inten figuration of can 79 and will in this instance move sity per unit area. It is then possible to stop slightly to the right. Shaft 72 will thereby rotate down the diaphragm of the enlarging lens in the slightly in a counter-clockwise direction carry conventional manner without obtaining objec ing with it the two levers 70 and thereby lower tionable patterns on the easel. ing the reflector plate 33. Moving this reflector While two or more spotlights give better re will bring it more nearly in focus with respect to sults than only one spotlight for reasons men 5 the condenser and spotlights and will, therefore, 28.36:303 8 increase the light output of the enlarger. Source of light, and & Eight collecting specia: See cam 79 has the proper configuration, the two flector which is st; east artially as eptic body factors may be made to cancel each other, i. e., of rotation, said gource of light, being positioned the light may decrease due to the increased mag in one and said diffuse refector ornally being nification ratio, but may increase due to the positioned in the other of the two focal goints oš lowering of plate 33, and as a, result of those two said ellipse, means to keep the sessity of the conflicting factors the light will remain constant. light inpinging upog said 2.Secog2Stant regards It is hardly necessary to point out that an era ess of the dists: c2 of S5.5 projector froEl Said arger with a light output independent of Eaa base, said means corages:g & Casa Raotiated 02. Ragnification ratio simplifies the enlarging teche 0. said structure, Szé 8, nec:32 is ri, includirig & nique very considerably. The operator now is can foilovying gegie, Sz. Oga;&tive Contact fit Saved all the tedious computations and estie said can, adapted 9 aii.25% a to Eatically the nates necessary heretofore to predict, tae ex position of said digEggs vyi.ie reflector relative to pOSure time because now, with a, constant light, said spotlight, whereby the specia?" Spotlight re output independent of the magnification ratic, 5 giector is focused age gais (i.33&e White reflectics any given negative will have a constant exposure in is normal gosia, 7,202 he distance of 32ic time, if printed on 2, given type of bromide paper. projector frog said, asse is 3rgest, it is pro Warious changes in the form, proportio, and gressively cegetages: Waeg, SS-Sci is as ce secoE sers minor details of parts Inay be resorted to withi 8&Ee: out departing from the principies or sacriticing Ef:SE, fiscaf.5S, airy of the advantages of the invention as defined in the appended claim. REaCSES (CBEE) What claim as Pay is: in a photographic enlarger which comprises a, Cae fEovyiig Segesences are of record is the supporting structure and a base and a projector 25 file of 63 is pate:a: assembly mounted slidably on said structure in USA; STAGES PARENES cluding a Support for a photographic negative, N2.23 Naire Site an enlarging lens in front of said riegative, which 24,233 Wheale: ------Sept. 26, 588, projects an image of Said negative upon said base, 223,353) Walties ------Apr. 24, 9. a focusing movement for adjusting the distance 30 633,838 2Yarne222&la ------sc. 25, 92? of said lens from said negative, a condenser toe Re. 038 33.333, et SS. ------July 7, 923 hind said negative, and an illuminating System 3,364,696 Steele et al. ------June 28, 1932 comprising an opaque diffuse reflector with a dif 837,650 28te? ------Nov. 5, 1932 fusely reflecting white surface positioned behind 285,393 SerioS ------. Dec. 25, 1935 said condenser on its optical axis and substan 35 2,754. Be! ------Ray 7, 1938 tially at its focal point, whereby an image of 3,326,836. into ------Staly 26, 1938 said diffuse reflector is projected by Said con 2,176,623 Seeshoefe ------Oct. 7, 1939 denser into the pupil of said enlarging lens, and 2,136,839 Sales ------S8i. 8, 940 at least one spotlight, offset with respect to the 2,198,0i4 O63------Apr. 23, 1940 optical axis of said condenser, pointing toward 40 said diffuse white reflector and adapted to ill 2,238,003 Becket &S.------Aps. 8, 194 luminate a selected area, thereon, comprising & 2,349,339 (3887ce37ey------Ray 23, 984