The Moving picture world (April 1920-May 1920)

734 THE MOVING PICTURE WORLD May 1, 1920 O J E CTI ON Hy F.H.RICHAKDSONT The Questions on Optics 1-| WHAT is the relative light giving I power per watt of energy taken • from the line, of an arc fed by D C through a motor generator set and A C taken through an "Economizer"? (P. 293-4). 12. What law is involved in distance of crater from lens, and how does it operate? (P. 157-8). 13. What is the limit of distance of crater from lens? As close as it can be set without undue lens breakage. 14. What direct effect on light economy has poor lamphouse ventilation? Ans. — It raises the temperature inside the lamphouse, thus compelling the placing of the crater further from the lens to keep down breakage. 15. What are the requisites of a good condenser lens? (P. 127-8). 16. What objections are there to a thickedge condenser lens? (P. 127). 17. Why should condensers have a true, well polished surface? (P. 127). 18. Should the surface of a condenser lens be ground? (P. 126-7). 19. Does color in a condenser lens do harm? (P. 128). 20. Name the various reasons why condenser lenses should be set as close together as possible without actually touching each other. (P. 115, plus the fact that lens charts are based on E F of condenser combination when lenses are set that way.) Some Real Mazda Dope Recently our old friend, Leo Smeltzer, chief projectionist, Kearny Theatre, San Francisco, told us he was getting "excellent results" with Mazda. Now the editor knows Smeltzer, and that he is a thoroughly competent projectionist, whose opinion in such a matter is worthy of serious consideration, hence we asked Uncle Sam to convey to him a message requesting further, detailed information concerning the propostion as a whole, and certain details thereof as well. Here is his reply: Answering your query as to clearness of details in my Mazda projected picture (We asked him it he did not lose much of the finer details of photographic shading through weakness of illumination. Ed.) as compared with when we used an arc, will say that prior to installation of Mazda we used 33 amperes D C through rheostats, and outside the softness of the light as compared to the arc the picture is absolutely as good, even to the finer details. I do, however, notice a hesitancy in the light piercing the dark blue tones some producers inflict on their titles, for which they should be arrested and summarially dealt with, or at least their service refused. We have discarded D C entirely, using A C through choke coil transformers, wound evenly for volts and amperes, the same being, of course, in series with the lamps. By the way, I find it a good scheme to drop the core of the coil to normal on leaving for the night, so that next day the lamps will be started on low amperage and gradually warmed up. Chief Trouble With Lamps. I find the worst trouble with the lamps themselves to be an imperfect seal. The manufacturers tell me they have as yet been unable to produce a perfect seal, which will withstand the high temperature. Another thing, the present type of holder, or socket is entirely too light In construction for perfect radiation of beat. So far I have not burned out more than Notice to All PRESSURE on our columns is such that published replies to questions cannot be guaranteed under two or three weeks. If quick action la desired, remit four cents, stamps, and w© will send carbon copy of department reply as soon as written. For special replies, by mail, on matters which, for any reason, cannot be replied to through the department, remit one dollar. QUESTION BOOKLETS. We have two paper covered booklets containing 160 questions designed as a guide to study. They Indicate what the projectionist should know. Either booklet, postpaid, twenty-flve cents; both, forty cents . United States stamps accepted; cannot use Canadian stamps. THE LENS CHARTS. Are Yon Working by "GnoM," or Do Yon E^mploy CTp-to-Date Methods r You demand that your employer keep his equipment In good order and up to date. He owes It both to himself and to you to do so, but you ofe It to him to keep abreast with the times in knowledge and in your methods. The lens charts (two In one, 11x17 Inches, on heavy paper for framing) are In successful use by hundreds of progressive projectionists. Don't "guess." Do your work RIGHT. Price, fifty cents, stamps. Address Moving Picture World, either B16 Fifth avenue. New York City; Schiller Building, Chicago, III., or Wright & Callender Building, Los Angeles, Cal. ^luiiiiiiiiiiiHiiiiiiiiHiiwiiuniiuiiiiiiiiiiiuuiiiiiiuiin one filament, though I have been obliged to discard some lamps after fifty days on account of discoloration of the glass — turning black — to such an extent that the light value was injured. My opinion, based on experiment. Is that the addition of a metal ring about one-half inch thick and one inch wide, clear around the top of the socket, and retained in close contact therewith by means of screws, would solve some of the diflJculty. For one thing it caused the lamps to last longer. One of the things which cuts lights heavily, and which must be very carefully guarded against, is a dirty reflector. This should be washed off with clean water occasionally. (Wonder about what friend Smeltzer means by "occasionally." Might be quite a stretchable term. Ed.) My shutters are 2-blade, reduced to the limit (Hugely Important with Mazda. With a comparatively weak illuminant the shutter may be reduced decidely more than with a brilliant light. Moreover the yellowish tint of the light, as compared with arc Illumination, adds to the possibility for shutter reduction. Ed.) and BOTH blades are perforated and set at extreme end of shaft, so as to catch as nearly as possbile an exact focal image of lamp filament (aerial image of condenser — Ed.) projected through pin-hole in dowser. The shutters should go two inches further out, but there is nothing to hang them on, which is a serious fault in present machine construction. (Tou can get extra length shutter shafts from the manufacturer. Ed.) Even so little as one-sixteenth of an inch with respect to distance from lamp filament to condenser surface makes or mars the screen results. Another thing, the spot Is much hotter, or seems so, and will fire any bits of film which lodge in aperture more quickly than will the arc; also It heats up the whole gate and aperture to such an extent that the film often buckles if threading Is done too quickly after shutting the projector down. Atralting: With Intere«t. I am awaiting, with considerable interest, the advent of a fifty ampere, or at least a 1,500 watt lamp, believing It will place Mr. A C transformer, mercury arc rectifier et al on the shelf for good and all, while at the same time consuming less wattage than the regulation arc. Saving In current has been about (average) »35 per month, with results as above set forth. Of course, no projectionist is afraid of work, but should some future one desire to sleep on duty the Mazda offers wonderful opportunity. Mazda Manufacturers Attention. The attention of manufacturers of Mazda equipment is pointedly directed to Mr. Smeltzer's remarks, because Leo Smeltzer is no tyro. From what he says with regard to illumination I take it he regards the Mazda, when properly and expertly handled, to be the equal of a well handled thirty ampere D C arc, BUT notice, take note, set it down that Smeltzer is a projectionist, NOT an "operator." He knows his business. He understands how to take advantage of proper shutter location and blade reduction. If he did not he most emphatically would NOT get the results he is getting. Make no mistake on that point. That would not. of course, be any fault of the Mazda, but of the man himself. BUT it would be well for those making Mazda installations to take note and, after setting the shutter at or as near the aerial image as possible, to reduce its blade to the last limit of possibility. It means a LOT more light in many, if not most cases, and unless either the installer or the projectionist gets that light the reputation of the Mazda will suffer. I cannot agree with Smeltzer's perforating stunt. In that we are sure he is in error. He gains no actual picture light by perforating the master blade, and surely there is no very bad inclination to flicker. That heat radiating ring sounds good to us. Mazda User* Take Note. We believe the time has arrived when we should welcome data from projectionists using Mazda equipment. Let us hear from you with your ideas as to faults in equipment, possible remedies and how you regard the Mazda as compared with arc light for projection. We submitted this to the Argus Lamp & Appliance Company, which corporation suggested that already some of it was rather out of date, and that before publication we go to Lynn, Mass., and look over the whole Mazda proposition in its latest developments. To this we agreed, but one thing after another has delayed the proposed visit for so long a time, with no certainty of making it in the immediate future, that we have decided to release this matter. We will follow, of course, with what we finally find in Lynn at a later date. Meanwhile, we will welcome short notes on experience of theatre managers and projectionists who are using Mazda, especially as to how the audiences have accepted it and what faults are found in the equipment itself.