The Moving picture world (January 1924-February 1924)

PP^OJ ECT] ON /. A. Convention The twenty-seventh convention of the International Alliance of Theatrical Stage Employees and Moving Picture Machine Operators of the United States and Canada will be held in the Hotel Gibson, Cincinnati, the week beginning May 19, 1924. It is not the desire of this department or its editor to butt into the affairs of the I. A., except insofar as seems necessary to point out those things which may be for the direct benefit of the motion picture projectionists' and the profession of motion picture projection. I would, however, like to point out the fact that" enormous damage is often done by select'ng as convention delegates men whose only qualification is the desire to "take the trip," and ability to "put it over" in the local. May I suggest that locals will do exceedingly well to select capable, progressive men, rather than union politicians to represent them? Who will the next president be? Well, that is a question no man can answer, but in my humble opinion the present incumbent, "Bill" Canavan, is a man than whom you are extremely unlikely to find a better. A Suggestion John Mutzgor, Projectionist, South Edmonton, Alberta, has a suggestion to make concerning condensers, as follows: In December 29 issue Brother W. Munn gives us the real goods as to measuring condensers. Here we place an order for condensers, only to find upon their arrival that they are not what we ordered, which means, of course, sending them back, with consequent waste of time and energy. Some condenser lenses have the words "Pearl White" on the end of the lens. These words seem to stay there as long as the lens itself lasts. Why cannot lens makers put the focal length of the lens on in the same way, so that supply houses can give a man what he orders? Enclosed find money for a lens chart. Good Suggestion No reason on earth why they cannot, brother Mutzgor — not even the shadow of a reason, except that manufacturers seem to have a well-fixed idea that accuracy in anything about condenser lenses is absolutely, completely and entirely unnecessary. You see, friend Mutzgor, for many years — in fact until Richardson got on the job and woke such men as Griffith up, almost any darned old thing in the way of a condenser which would get a decent looking spot at the aperture was considered "good enough." Such things as "arc distance" and the ill results of divergence of the beam between the aperture and projection lens were unheard of and unknown. In fact when I first made the assertion that light was lost by divergence of the beam I was pronounced just plain crazy, and by some pretty high-up optical men, too. Groped In Dark I groped around in the dark for quite a while seeking knowledge. I knew there was something wrong, but neither I nor any one else knew just what it was. Finally a projectionist named James, down in Camden. EDITED BY F. H. RICHARDSON New Jersey, made a series of photographs of the projector optical system action, and started us off on the right track. Then a man up in Ashland, Wisconsin, chipped in with some excellent ideas, and finally John Griffith shied his hat into the optical ring, from which time forward we began to really understand that it was necessary to do something more than stick in the focal length of condenser which came most handy, or which happened to suit our fancy, if we wished to get efficient results. Your suggestion is a good one. Manufacturers usually wrap lenses in paper marked with the focal length. Often these wrappings get mixed and there is trouble. The attention of supply houses and lens makers is directed to the fact that if "Pearl White" can be etched on the edge of the lenses, so can the focal length. It is respectfully suggested that you get busy and do it, Mr. Lens Maker. Warning Theodore P. Hover, Visual Instruction Department Central High School, Lima, Ohio, says some interesting things, as follows : First, a favor of you: Would you publish names and publishers of any magazine there may be on projection; also any good books on that subject? While on my vacation last summer I visited theatres all the way from Chicago to Cincinnati. I met many projectionists, and still more operators. Saw some wonderful projection rooms; also many "booths," which were just that. On pages 290 and 291 of the Bluebook of Projection you say that commercially pure carbon-tetrachloride may be used to dissolve oil and dirt from film stock (Whoa! Must stop to dispute you right here and now! Did not say any such thing! Said commercially pure tetrachlorethylene, made and sold by the Dow Chemical Company, Midland, Michigan, which may or may not be the same thing. I dunno. What I said was on the authority of the Eastman Company, and heaven knows they should know if any one does. — Ed.) Question That the chemically pure article would be useful for this purpose I will agree, but the commercial product known as "Pyrene," "P. R. X. Fire Extinguisher," "Non-Inflammable Spot Remover," and under other trade names, NEVER! I give voice to this warning because on my trip I saw men cleaning film with these materials. This they did by holding a cloth saturated with the "cleaner" against the face of the print while rewinding, thus doing grave injury to the print. One objection Is that the moisture in the film combines with the tetrachloride, and the mixture evaporates, leaving the film dry and brittle. Secondly, the commercial article under discussion contains impurities, such as carbon bisulphide (I believe that Is it) which would tend to bleach the film. Hence, safety first and use dry cotton flannel or nothing at all. I might add that carbon tetrachloride, besides being an excellent Are extinguisher. Is good for cleaning the projector mechanism and around generator commutators where the use of gasoline Is forbidden. I would warn all projectionists to not mistake carbon bisulphide for tetrachloride, as the former Is a violent explosive and the latter a Are extinguisher. Well, gentlemen, I don't know anything about this, except that you will find the Bluebook says distinctly that PURE chemi cals are recommended. I even gave the name of a maker whose goods may be relied upon. If it is true that Pyrene and other similar compounds injure prints by making them brittle and setting up a tendency to fade, we should by all means know that fact. I shall refer your letter to the Eastman Company, with request for an opinion. Lens Diameter Recently Jack Levine, Rialto Theatre, Leominster, Mass., requested information with regard to what diameters of projection lens might be used with a Powers projector. In order to get the latest information I sent his letter to the technical department of the Powers Company, with request for the correct dope. The following letter was received in due time : * • * I have had a blueprint prepared, copy of which is inclosed. It shows the assembly of the new Powers front plate, and gives all the dimensions and relative positions of the front plate, the lens mount and mechanism. You will see that a "half-size" lens may be used, and that the full diameter of the back factor is available to a point 3% inches from the aperture. Lenses which have a shorter working distance than 3% Inches must have the diameter of the rear factor reduced to approximately two (2) Inches outside diameter. Adapters are supplied with the lens mount to accommodate the No. 1 and No. 2 sizes projection lenses of the various makes. What Can Be Used The actual clearance from top of the interfering shaft to center line of aperture is 1.184 inches, hence a 2-inch outside diameter lens would clear the shaft quite sufficiently to prevent any possibility of contact and vibration. Through an error the letter (Levine's) I sent was not returned, hence I don't know positively what the E. F. of brother Levine's lenses was, but think it was seven inches. If that is right, then I think a full size back factor of a "half-size" lens could be used. BUT, as I remember the matter, it would be better to use a small diameter lens and a Cinephor condenser. The dimensions of two of the leading makes of projection lens on the market may be had from pages 147 to 150 and pages 157 to 158 of the Bluebook. Some while back I had all the lens makers figure the working distance of all the various focal lengths of their lenses, but the data has somehow been mislaid, and though I've put in a solid hour searching I have been unable to find it. The Bausch & Lomb Company make a 7-inch projection lens, the free diameter of the back factor of which is 62 mm. I think the Gundlach-Manhattan Company also makes such a lens. The Snaplite is not made that way, the free diameter of the rear factor of its 7 inch E. F. lens being only 47 mm. From Calgary D. B. MacKenzie, secretary Motion Picture Projectionists' Local Union, No. 302, I. A. T. S. E. & M. P. M. O., Calgary, Alberta, writes : I have been Instructed to advise you '.hat this local heartily concurs In your recommendation that the term "Projection Boom" be used In preference to "Projector Room."