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Author Topic: Question About 1916 (!) Projector Ted Schaar Film Handler Posts: 3 From: Brookfield, Wisconsin, USA Registered: Mar 2014 posted 03-31-2014 08:41 AM                        I’m writing a story about early movie theaters in my hometown of Janesville, Wisconsin. One of the things I’m trying to figure out, decipher, or interpret is the following from an article (attached) about a then-new theater called the Beverly that appeared in the *Janesville Gazette* on April 20, 1916: “Two projecting machines will eliminate any pause between reels; the Beverly will be the only picture theater in Janesville with two machines and also the only one with a direct electric light converting system…” The part I don’t understand is “…the only one with a direct electric light converting system…” I'm hoping someone here might know what this is referring to. Thanks, Ted  |  IP: Logged Konrad Schiecke Film Handler Posts: 26 From: Mt.Prospect,Il. Registered: Mar 2000 posted 03-31-2014 08:58 AM                    Refers to a direct current arc lamp system. Others of that era used ac arcs.  |  IP: Logged Ted Schaar Film Handler Posts: 3 From: Brookfield, Wisconsin, USA Registered: Mar 2014 posted 03-31-2014 09:03 AM                        Thanks, Konrad. Are there advantages of a direct current arc lamp system versus an AC system? Would viewers notice any improvement in the look of the film image?  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 03-31-2014 02:21 PM                        "Direct electric light converting system" = what we would now call a rectifier. quote: Ted Schaar Are there advantages of a direct current arc lamp system versus an AC system? Would viewers notice any improvement in the look of the film image? High intensity carbon arc lamps need a low voltage, high current DC power source to work at all. The essential point this story is trying to make is that the projectors are equipped with high intensity carbon arc lamps (the technology was essentially invented by Elmer Sperry in the early teens, and started to be used in movie projector lamphouses at around the time your theatre opened), not gas/chemical illumination (e.g. limelight) or lower intensity, AC-powered arcs. In short, it would be like a theatre advertising that it had 4K laser projection now - the state ot the art in imaging technology. Incidentally, are you aware of the Center for Film and Theater Research at the University of Wisconsin-Madison? I'm guessing that their document archive might have material relating to film exhibition in the state which could be relevant to your research.  |  IP: Logged Ted Schaar Film Handler Posts: 3 From: Brookfield, Wisconsin, USA Registered: Mar 2014 posted 03-31-2014 02:31 PM                        Many thanks, Leo.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 03-31-2014 05:28 PM                    How did they avoid shutter flicker with an AC arc?  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 03-31-2014 05:36 PM                        My guess is that they didn't, and that they didn't care. In those days, the illusion of a moving image was so remarkable in itself that a flicker or strobe effect was just accepted as coming with the territory. So when the DC, rectified current lamp came along and got rid of a lot of the flicker, it was sold as being a step forward, which indeed it was.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-31-2014 10:05 PM                        Leo. I see no errors in your process.  |  IP: Logged Lindsay Morris Expert Film Handler Posts: 233 From: Darlington, WA, Australia Registered: Sep 2002 posted 04-01-2014 05:21 AM                     Not having ever run a machine on 60Hz supply as in USA I cannot comment... But on our 50Hz supply in Australia the flicker or more correctly the strobing of the AC fed arc timing with the 24FPS shutter would produce a slowly changing intensity of the screen light. The quick and dirty fix was to wind a few turns of the old fabric type insulation tape onto the motor drive pulley and slightly increase the speed to around 25FPS and the strobing all but ceased. In those days as well the slight increase in speed ever so slightly improved the top end frequency response and had barely any effect on the sound of the actors voices. The later higher frequency rotary converters available took the arc AC frequency up to about 400Hz I think it was and problem solved....but cost a lot. The insulation tape trick was cheaper and very popular amongst AC mains arc users Lindsay  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 04-01-2014 06:20 AM                        quote: Steve Kraus How did they avoid shutter flicker with an AC arc? Maybe just crank at 15fps? Assuming 60Hz power and a 2-blade shutter, that should do it. But wasn't DC municipal power available at that time, too? Why not just use that?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-01-2014 07:44 AM                     The original low intensity arcs had a very large diameter carbon and as such the thermal lag tended to eiliminate a lot of the flicker By the 40 Ashcraft came out with the cyclex which used ac 7mm carbons and a 400 hz mg set  |  IP: Logged John Eickhof Jedi Master Film Handler Posts: 588 From: Wendell, ID USA Registered: Jan 2000 posted 04-01-2014 12:08 PM                        In the early days, for AC incandescent and AC arcs, the use of three bladed shutters(at silent speed 15-16 fps)increased the cutoff from 30-32 cycles to approx 48 cycles thus there was still some flicker but more so there was the slight variation in the light overall (variable light output as the shutter would interrupt the AC crossover) And of course there was an additional loss of light on the screen. However, 3 bladed shutters had one larger blade that barely covered while pulling film down, the other two 'cutoff blades' were smaller and the shutter only lost approx 5-8% more light than a conventional two blade. Once sound speed was established, larger DC arcs were being produced so the two blade shutter was the standard and still cut off at 48 cycles. Thus it was above the avarage person's flicker thresh hold.  |  IP: Logged Simon Wyss Film Handler Posts: 80 From: Basel, BS, Switzerland Registered: Apr 2011 posted 04-05-2014 01:51 AM                     quote: Leo Enticknap the technology was essentially invented by Elmer Sperry in the early teens Sperry stole the invention from Heinrich Beck (b. September 20, 1878, d. August 17, 1937). Deutsches Reichspatent, number 262913, to Körting & Mathiesen, Inc. of Leutzsch-Leipzig, September 13, 1910. A perfectly working prototype was presented to the German navy in 1912. Beck got stuck in the U. S. A. at the outbreak of the war and could only return home in 1920. The American patents were sold to GE. http://www.becklaser.de/heinbeck/hbeckframeset.html  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 04-05-2014 11:00 AM                        Interesting! He has certainly slipped under the radar of the mainstream technological history books. Has any substantial biography or paper been published about him in English? I'm also wondering if a similar situation emerged in France and Germany with high-intensity carbon arcs as did with the Tri-Ergon optical sound patents: that the American manufacturers were severely limited in their ability to sell into the European market, because the technology had essentially been invented independently by others at around the same time, but whose patents protected them in much of Europe but not in the US (hence US-made variable density sound cameras being virtually unheard of in mainland Europe).  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 04-05-2014 06:24 PM                     quote: Gordon McLeod By the 40 Ashcraft came out with the cyclex which used ac 7mm carbons and a 400 hz mg set I used to work at a theater that had a pair of old Cyclex lamps & MG sets in the basement. I still have the manuals. The Cyclex lamphouses ran at 96hz.(not 400hz) You can find quite a bit of interesting info on the old Cyclex lamps if you look through the 1939-40 issues of International Projectionist.  |  IP: Logged

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