The Film Renter and Moving Picture News (Nov-Dec 1922)

Nov. 4, 1922. REAR PROJECTION. | To the Editor or THE Fitm RENTER AND MovinG Picture NEws. IR,—We have read with interest the article on ‘* Rear Projection,”’. which appeared in your issue of the 7th inst., and take the liberty of suggesting. that the reference made to the supplementary lens in the fourth paragraph, headed ’ ‘* Experiments with Lenses,’’ should have been coupled with the name of J. H. Dallmeyer, Limited, as we invented and placed on the market this special supplementary lens, which, when used with one of our pentac anastigmat projection lenses, entirely overcomes the difficulties usually associated with ‘‘rear projection.’" We are sending herewith advanced particulars of the supplementary lens, also one of our kinematograph catalogues, on leaves 10 and 11 of which you will find particulars of our pentac anastigmat projection lenses. We might add that a new catalogue is at the moment in the printer’s hands, and in this catalogue will be found a considerable amount of information dealing with the supplementary lens and pentac anastigmat projection lenses, the latter being listed in focal.lengths of 1l}in., 1fin., 2in., and 2jin. We are in a position to demonstrate here at our showrooms the advantage of this-system-of lenses, and give a perfectly satisfactory picture, 6ft. wide, with even illumination and critical definition with a throw as short as 9ft. Yours faithfully, J. H. Dauimeyer, Lrp. The following are the particulars referred to.: The difficulty of projecting a large picture with a short: throw has now been overcome by the introduction of a new supplementary.lens. which ig manufactured in various forms to fit the majority of standard kinematograph projectors on the market. This lens, which is rectangular in shape, is made in suitable focal lengths to suit our pentac anastigmat projection lenses, which range in focal: lengths from 1}in. to 8in. The lens is fitted to the gate of the projector between the film and the condenser, and it is necessary to drill four small holes: in the gate, which: have to be suitably threaded to take the small fitting which we supply. When the lens is fixed in position it is possible to evenly illuminate the whole of the sereen, the absence of dark corners being most noticeable. Should a pentac anastigmat projection lens be used in conjunction with the supplementary lens, critical definition can be obtained right to the corners of the sercen. The addition of the new supplementary lens enables a large kinematograph picture to be projected with a very short throw, the quality of the picture being equal in all respects to that projected with, say, a 5in. Dallmeyer Projection Lens. kinematograph projector, it is impossible to forward a sample As these lenses have to. be specially made for each on free ‘trial, but, of course, our usual guarantee is extended to cover every Jens supplied. | We are in a position to demonstrate here at our showrooms the complete apparatus fitted to. a Gaumont Chrono Projector. The picture projected is approximately 6ft., with a throw of only 10ft. Digitized by Go gle THE FILM RENTER & MOVING PICTURE NEWS. (Technical Supplement). 85 STRIKING SUCCESS OF THE NEW SUNLIGHT ARC. | HF installation of the latest development in projection— I Duncan Watson and Company's new Sunlight Are—at~ the new Super-Kinema at Lford, has amply demonstrated its success. ‘There was a brilliant light throughout the screening, and this was one of the material contributions to the highly satisfactory opening performances. This projection lamp is designed with one main object in view—to provide the brightest possible light. source. for illuminating the screen. -To get ‘this extremely bright projection light the rare. earth cored positive carbon is arranged in a rotating holder, just as with the producing studio lamp, only this. time the positive carbon is of only thirteen millimetres diameter, -and is burned with an eleven millimetres copper-coated’ negative, the positive carbon being horizontal, and the negative one fed up to it at an obtuse angle of 130 degrees. Any current from 70 to 120 amperes can be passed through this size carbon, and there is no doubt that twice or three times as brilliant a light is obtained as the brightest possible light hitherto available, and of an intense blue whiteness, besides which the ordinary are light appears positively yellow. KINEMA ENGINEERS IN AMERICA. NHE semi-annual convention of the Society of Motion I Picture Engineers, which was held at Rochester, N.Y., October 9-12, promised to be the most sucecssful ever held by that body.There was a large attendance of members and others interested in the practical scientific phases of the motion picture industry. The following papers were among those read at the convention : ‘‘ A Motion Analvser,’’ by Dr. Hermann Kellmer; *‘Accurate Methods fer Expressing the Performance of Lenses,’’ by Mr. Wilbur B. Rayton; ‘‘A Demonstration Model for Showing Lens and Condenser Action in the Motion Picture Projector,”’ by Mr. Sander Stark: and ‘‘ Practical Effects of Distance of Projection and the Projection Angle,” by Mr. F. H, Richardson, Original from NEW YORK PUBLIC LIBRARY