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Author Topic: How did a Brenograph work? Tim Ruf Film Handler Posts: 1 From: Brown Deer, WI USA Registered: May 2007 posted 05-23-2007 10:32 AM                     Greetings, I am working on an article about a theater that was atmospheric style, complete with blue ceiling and twinkling lights as stars built in - if you are familiar with Eberson, it was along the lines of his design. I am told that the theater had a Brenograph and it was used to project clouds that moved across the ceiling. I have downloaded the manual on the loading and use of the Brenograph that is in the manual section, but unfortunately, still do not understand how it works its magic. Could someone who perhaps has seen one in operation or operated one in this fashion tell me how the effect was achieved? Was it a manual operation to transition between two slides or how else? Thanks in advance for your help.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 05-23-2007 12:08 PM                     Tim, the Brenograph is a complex piece of equipment, which can be fitted with many different attachments, and configured to do many different things. Basically it consists of two low-intensity carbon arc lamphouses, each fitted with a condenser lens. at the front of the machine, in front of each lantern is a turret which can hold four projection lenses of different focal lengths. These lenses are fixed in position, unlike most projectors where they can be moved backwards and forwards for focusing. The image from the Brenograph is instead focused by moving the lamphouse, and with it whatever it is that is being projected, along the rails, relative to the lens. This is done by turning the crank handle near to each lantern. Attached to the front rails are small metal indices, which can be moved to indicate a correct position for some particular job. For example, the Brenograph could be used to project moving patterns onto the curtain before a show, but then project song words from a slide onto the screen; The curtain would be in a different position to the screen, the slide holder would be in a different position to the effects glass holder, and the lens could be a different focal length, so the lamphouse would need to be moved between the two uses, and the indicies could be set up beforehand to indicate the correct positions. The image from the two lanterns was not projected directly onto the screen, curtains or whatever, but via a periscope arrangement of mirrors. the light from the top lantern would hit a fixed mirror at 45 degrees, which would direct it downwards, then a second mirror would turn it forwards again. The beam from the lower lantern was directed upwards and then forwards, in a similar way. There were two reasons for this: firstly, it brought the two beams closer together, so the port could be smaller, and secondly, the second mirror could be tilted, in two axies, by adjusting screws, so that the image could be moved about, without moving the whole machine. The second mirror was actually two mirrors, each adjustable independently, mounted on a sliding turret, so that they could be pre-set, and either could be quickly moved into position. You could even move them while operating; for example to project an image of a setting sun. Each lantern was fitted with an iris do dim the light, and these could either be used independently, of they could be locked together, so that the image could be disolved from one lantern to the other by moving a single lever. The Brenograph could project standard size glass slides, textured glass effects plates, cut-out gobos etc., and there were vertical and horizontal shutters to shape the beam, and a second iris in the focal plane could be used to adjust its size. Colour filters could be used, either singly, or in a rorating colour wheel. Put all that lot together and you could do just about anything with it. I seem to remember that Brenkert said that it 'Projects everything except the motion picture'. I've only ever actually operated one once, many years ago. It sometimes helps to have three or four hands!  |  IP: Logged Bill Enos Film God Posts: 2081 From: Richmond, Virginia, USA Registered: Apr 2000 posted 05-23-2007 02:14 PM                     Stephen covered it pretty well. The only thing I can add is that we have one in use every night, original except that the carbon arcs have been replaced with a couple HX 754 halogens. Come over & see it.  |  IP: Logged Bruce McGee Phenomenal Film Handler Posts: 1776 From: Asheville, NC USA... Nowhere in Particular. Registered: Aug 1999 posted 05-25-2007 03:16 PM                     I believe that the FOX Theatre in Atlanta still uses their Brenograph. Nice effects.  |  IP: Logged Paul H. Rayton Expert Film Handler Posts: 210 From: Los Angeles, CA , USA Registered: Aug 2003 posted 05-25-2007 09:03 PM                    Here, for you, Tim (in case this illustration isn't in the manual), and for anyone else who has never seen such a beast as a "Brenograph", is a very detailed illustration of a Brenograph. These were from the days that projectionists were right at the cutting edge of technology. You didn't operate this without some real instruction time, coupled with experience! [Illustration being sent to Administrator, size too big for direct inclusion. It should appear shortly, I hope...]  |  IP: Logged

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