new agreement, all employees reporting for work on January 3d would do so with the understanding that they are to work under the conditions of the agreement recently presented by the employers to the Union. We did not lock out our employees as Union men, and would welcome them back under the terms submitted. All we ask is a reasonable reduction in wages, a right to operate our plants in a manner that will insure a full day's work for a day's pay, which is only a square deal, and we will insist upon getting it.

We sincerely regret that a break in our relations has occurred, and hope that by the time this article goes to press, our employees will have realized the fairness of our proposition. In the meantime we will operate our plants the best we can. "ST. LOUIS."

Milwaukee

This is hoping that the new year of 1922 will be a banner year in our industry, and to you and all, the Wisconsin Photo-Engravers' Club sends greetings.

In spite of what Mr. Babson predicts, we hope that 1922 will be as good as 1921, if not better. The industrial situation here in Wisconsin and Milwaukee is about the same as it has been for the past ninety days. Factories are resuming; but only on part time. One of our largest industries, which employs 6,000 men, has divided its force so that each man works twelve days in a month of twenty-four days; but the photo-engraving industry right now could stand much more work. All of the shops have been keeping their men employed throughout the year and we anticipate better results in the future.

Right now we are in the midst of our negotiations with our men, and the whole country is involved in the same. We believe that the final results will be beneficial to all concerned, and we only hope that this year will again restore us to our normal conditions, which are bound to come.

Our Wisconsin Photo-Engravers' Club has been meeting continually, and at our annual meeting we elected our new officers for the ensuing year, and Mr. E. Mandel was made our chairman for the ensuing year.

The Wisconsin Photo-Engravers' Club sends greetings and wishes all a prosperous New Year.

HENRY PETRAN.

Baltimore-Washington

Washington and Baltimore are sort of marking time in the labor troubles of the present time. Washington employees' agreements do not run out until the first of February, and I believe Baltimore runs until sometime in July of 1922. The Washington employers have notified the men that there will be a new agreement presented them, but, naturally, we are waiting to see what happens elsewhere. We hear this morning that there had been some trouble over the country, and we want to impress upon you fellows that both Washington and Baltimore are behind you in everything you do and that we are "pulling" for you every minute.

The last meeting of our Association was held in the new plant of the Maurice Joyce Engraving Company, where we were all the guests of Harry Stiles, its

"Boss." We certainly had some party-roast duck and everything. But then, most of you fellows know what sort of a party that Harry would put across, and I know that you all wish that you could have been there.

Requirements of a Process Lens

RALPH GRENELL

Manager Douthitt Diaphragm Control Corporation

MAX.

It is impossible for the operator to make a better negative that his lens is capable of. In the good old days, the engraver had his peck of trouble, and not an inconsiderable bit of it was caused by the limitations of the best lenses which he was able to procure. In those days, surely, the engraver was continually up against the stone wall of "It can't be done.”

Just imagine one of our big modern engraving institutions operating with Meniscus or Achromatic Menicus Lenses. Rapid Rectilinears were a great step ahead. The freedom from distortion and the sperical correction proved a great help to the engraver. Yet this lens could not be corrected for both curvature and astigmatism in the same lens. Some Rectilinears are still in use.

After the invention of the Rectilinear, a long period of years passed, and it seemed that better lenses could not be made. Optical mathematicians carried these lenses to the highest corrections that available materials would permit. Science then stepped in to do its share when new types of glass were developed by Professor Abbe and Dr. Schott, in Jena, Germany. Shortly thereafter followed the invention of the first Anastigmatic Lens by Dr. Rudolph, also of Jena. A rapid succession of improvements in formulae and glass followed, until up to the present time, when it is possible to obtain lenses corrected to take care of all lines of engraver's work with the same lens.

In so far as speed is concerned, anastigmatic lenses have been developed along two types. One being made for use with very large aperture and of great speed, for portrait and speed photography. The other type, of comparatively small aperture, for use where definition, color correction and other finest possible corrections are necessary. In this latter class fall the Process Lenses. In their case speed is not considered. Needle point definition, microscopic, for the finest reduction line negatives is more important. Absolute color-correction, absolute flatness of field, absolute freedom from distortion are of greater importance. A speed of F: 8 is sufficient in a Process Lens, since the largest aperture which it is necessary to use is about F: 8-which is necessary in making a three-time enlargement with 150 a screen. For this reason, nothing is sacrificed in a

Process Lens.

The manufacture of a Process Lens involves the most beautiful of optical balancing propositions. It is simple to overcome any single optical fault, but there are many of them, and each correction must be made without disturbing others. Like a teeter-totter,-push one very objectional feature down and another one, possibly several, come up. Chromatic Aberration, Astigmatism, Spherical Aberration, Curvature of Field, Distortion, Flare, Coma, Axial Aberration and Oblique Axial Aberration must each be corrected for, without throwing the correction of any of them out of balance.

Chromatic Aberration. The colors of the spectrum have different wave lengths. Through a simple, or uncorrected, lens, these different colors focus at different planes. The corrected anastigmat brings these different colors to focus on the same plane, making possible commercial process photography.

Spherical Aberration.-Caused by the curved construction of lenses. Objects imaged through the central zone of the lens focus on a different plane than do those which pass through the marginal zone. Where this is not entirely corrected for, even modern anastigmats will show intermediate aberration, known as "local" or "zonal" aberration.

Astigmatism. Failure to image both vertical and horizontal lines at the edges of the plate. This aberration was most difficult to overcome-hence the name, "Anastigmat."

Distortion. Inability of the lens to image straight lines as such. Straight line appearing on the negative either concave or convex.

Curvature of Field. When a lens focuses, not in a plane, but in saucer shape, similar to the spheroidal surface at the back of the human eye. In this case,

if the center of the plate is in sharp focus, the plate must be moved either nearer or farther from the lens in order to bring objects in focus at the edges of the plate. Coma.-A one-sided indistinctness of objects, appearing away from the center of the plate, and increasing toward the margin, where a point seems to have a tail like a comet, from which "Coma" is derived.

Flare.-Caused by internal reflections of improperly curved lens surfaces. In this case the negative will show an area of light which covers both high-light and shadow, more or less distinct, depending upon conditions.

Outer Axial and Oblique Axial Aberrations. In one case the outer axial rays are refracted more or less than the axial rays, causing lack of definition and distortion. The latter is caused by the different refraction of oblique rays at the center and margins of the lens. Generally included in spherical aberration.

It is no wonder that optical calculations and science needed to progress in order to produce an anastigmatic lens and bring it to perfection. The invention of the Barium Crown and Flint glass greatly improved the methods of manipulation, which improved with highly developed measuring and testing instruments, and the "will to do" have brought about an equilibrium of conflicting defects which gave the world most remarkable and efficient photographic objectives.

Another great advance in photographic optics was made possible by the invention of the Iris Diaphragm. This made possible an infinite range of apertures, invaluable in the present method of highly scientific halftone negative making, where great variations in aperture are necessary for correct optical results with different screens, varying screen distances and bellows extensions. In fact, it has now become almost impossible to take advantage of the very recent scientific device, the Diaphragm Control, without the Iris Diaphragm.

The barrel of a highly corrected lens, though its function is merely to hold the optical elements of a lens in their correct relative positions, demands the most accurate machining on especially designed optical lathes, the spindles of which must revolve absolutely true, without error. The Graf Optical Company is using copies of German lathes which have proved best adapted for this particular work. The optical elements of the Graf Process Lens consist of two positive lenses, made of Crown glass, the outside lenses (Crown glass is, unfortunately, of a

very soft quality, and must be cleaned with extreme care); two negative lenses, made of Flint glass; Iris Diaphragm and Waterhouse Stop. The lens elements are made as thin as possible, with colorless optical glass. In this way, loss of light, through absorption, is reduced to the lowest minimum. It is for this reason that users of Graf Process Lenses have found that at same aperture they will give the same exposure in less time.

The first attempt of the Graf Optical Company to make a Process Lens was not a hundred per cent success. A good lens was made by adapting a general photographic lens to this type of work by decreasing aperture, and by higher and more accurate corrections along general lines. Finally, after studying the engraver's needs in actual work in several large engraving plants, and after consultations with experts, Mr. Graf became convinced that a lens could be calculated to cover the special needs in this field more thoroughly and efficiently than any lenses available. This new problem became his hobby. Each experimental lens was tested in actual practice on the most difficult types of four-color and reduction line work. And each successive test demonstrated that very radical changes could be made in anastigmatic construction where speed was of no value; that is, excessive speeds to F: 6.3 and F. 4.5. Corrections which were necessary to enable a fast lens, at full aperture, to completely cover a plate, with a flat field, and still be a good lens, were unnecessary. Changes could be made-changes in favor of the Process Lens. By gradual degrees, a formula was evolved, in which all corrections met in "Process" harmony. The new Graf Process Lens passed the tests of several of America's most expert and scientific plate-makers.

An amusing incident occurred during some of the final tests of the new lens. It was being used on what was considered the best camera in the operating-room of one of the largest and most progressive engraving houses in the Middle West. The camera was focused on a special, very fine line, test drawing,-reduction about ten times. The ground glass showed a beautiful image under ten-time magnification, but the negative was a disappointment. Another was made, with the same result. The camera was then focused by placing a sheet of ground glass in the plate-holder, ground side forward. In the next negative it was found that the fine lines were "cut through" to the glass-a perfect negative. The camera ground glass did not register with the emulsion side of the plate. For this reason, we would suggest that, where a new lens is being tested, the ground glass of the camera be checked up in this manner.

It was also found, in these tests, that the very slightest underexposure favored the lens, and a very slight overexposure affected the definition to what seemed a disproportionate degree. For this reason, several negatives were made for each test, in order to be assured of accurate exposure.

After succeeding in the perfection of the Process Lens, Mr. Graf turned his efforts to the manufacture of prisms which would be of a quality in keeping with the newly developed lens. This was purely a matter of improved machinery, workmanship and more accurate measuring and test instruments. Graf Prisms are optical masterpieces. Each prism is designed for its respective lens, and will not distort the image or reduce the working angle.

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News From Abroad

One of our readers has been in correspondence with several photo-engravers in Continental Europe, and submits the following news items, which undoubtedly will be interesting to the BULLETIN family.

Several photo-engravers in Germany are anxious to make plates for Americans. One of them writes that he understands there is a great deal of this work being done in Germany for America, and he is anxious to get some of it. No details as to prices, service, etc., accompany the letter, and we are left hanging in the air as to what German photo-engravings might cost. Before the decided drop in the value of the German mark, the prices of photo-engravings in Germany were practically on a par with American prices. Since the mark has dropped from twenty-four cents to about one-half cent in value, figure out for yourself what this sort of competition would be like. No doubt we have all read articles in the newspapers referring to "dumping" of foreign-made goods into the American market. Some of us, perhaps, didn't know just what this meant, or, at all events, we figured it did not interest us to any great extent. Several months ago a letter from Germany stated that photo-engravers were receiving wages which, when converted into American dollars, amounted to about $5.00 or $6.00 per week. Since then, the mark has depreciated more than fifty per cent. Allowing for duty and everything else you can think of, there is still a considerable spread between men working for one-tenth the wages paid in the United States and our own cost. It is fair to assume that the products of men working for less than $5.00 a week can be placed on the market in this country at a price considerably lower than we could possibly hope to sell at. This situation. will bear watching, and it is requested of our members to notify the BULLETIN office of any facts or details bearing on this situation that may come to their notice.

The same complaint against German competition in plate-making lines has also come from England, as the various English publications have indicated during the last few months. Several writers have stated that the German prices were so attractive that English firms could not be restrained from buying German plates even through an appeal to patriotism.

An engraver from Belgium writes that practically all of the photo-engraving firms in Holland are closed, and those which are still working have reduced their forces about ten per cent of their strength in 1914. The Dutch photo-engravers have found it easier and more profitable to have their work executed by the Germans, on account of the low value of the mark compared to the Dutch florin. This enables them to make a bigger profit by having their work done in Germany and Austria than by making the plates themselves. No one knows how all this will end, but the future appears to be gloomy indeed. It is reported that the Germans with their low prices are overspreading all Europe with their merchandise. The foregoing points out pretty plainly that the diplomats made a botch of the Peace Treaty several years ago. They made a similar botch of the reparations settlements, and, instead of punishing the Germans, they are punishing themselves. There is only one way to remedy this situation, and that is for all of the principal nations to lend a hand in restoring normal exchange, not because they necessarily want to help their former enemies, but in order to help themselves.