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Post by Ron Walker on Sept 18, 2022 17:14:00 GMT -7
Posted by: albert Sep 11 2013, 07:17 AM Dear Friends from OSC! After 5 years of development, a few tons of red tape and financial discussions, my own "the dream is alive" project is finally coming together! Let me say that I would not have had the courage to even consider this without your shining examples! So finally, the town of Bad Toelz south of Munich, Bavaria, Germany decided to build a planetarium with an 18 ft. dome. The projector will be the Zeiss ZKP 1 I have amply shown in these pages. I would like to show you how the dome was made for our new planetarium. Since we are inside a 4 storey building the dome goes from the cellar to the ground floor and the upper part is fully visible. From the very beginning, I wanted to avoid the claustrophobic effect of a closed cylinder for the planetarium. In an 18 ft dome this gives the effect of being inside a well. So I suggested that the dome should be suspended only along half of its bottom and the rest be open to a larger room. This also avoided the problems of getting into the planetarium room, no doors! And no problems with regulations of emergency exits and fire proof construction, as people cannot be trapped inside. The springline is at 6 feet as needed by the Zeiss. I am not sure if a lower springline is a good idea, I like the effect of the sky being farther away. For a video projection, this will also give the illusion of a sharper image. It also eases some of the acoustics problems. The upper part of the finished dome looks a lot like a pizza oven....note the heavy outer rim that was made in steel enforced concrete to take up the considerable sideways forces from the dome.We will probably add a painting of constellations on the surface. The room will be used for various exhibits.
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Post by Ron Walker on Sept 18, 2022 17:15:30 GMT -7
Posted by: albert Sep 11 2013, 07:57 AM This is what the main room looked like in May. The spring line is at 2.10 meters, roughly 6ft, which is given by the Zeiss projectors structure.. The Zeiss projector is a historic instrument and will therefore not be modified. The dome being open will also give methe opportunity of using the larger space around for concerts or other shows. A look down the rabbit hole where the dome will come....believe me I had some sleepless nights before the final decision was made how the dome would be built. In our first discussions with architect UWE MERTENS we thought about building this dome from thin plasterboard walls in "gore" segments with a steel or aluminum frame behind them to keep them in shape. No company wanted to guarantee the necessary precision. And the back side of the dome would not have been presentable the way it is now. So the architect came up with this masonry idea. After all they did it centuries ago, why not do it like in the old days? I swallowed but got used to the idea quickly. Finally a local company was found with experience and the guts to tackle this unusual project. We have a lot of historic baroque churches in Bavaria, and many of them have exterior or interior dome structures. So doing a dome in bricks and plaster was not something entirely new. But to my knowledge this is the first dome ever to be done entirely in this technique for a planetarium .You can do a lot with local people if there is a tradition of doing things a certain way. It really resembles the way a pizza oven is built, but its on a much larger scale. A study of the statics had to be made first.
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Post by Ron Walker on Sept 18, 2022 17:16:31 GMT -7
Posted by: albert Sep 11 2013, 08:11 AM So in June 2013 the dome work began. The first thing to do was to build a solid scaffold structure at the spring line. This would be used for all further work so it HAD to be solid and very well leveled. The first step was to cast a steel reinforced concrete ring to take up the considerable load of the dome and the lateral forces. Then came a very precisely made wooden pattern or scaffolding made of one inch (!) plywood in the shape of the dome.
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Post by Ron Walker on Sept 18, 2022 17:16:50 GMT -7
Posted by: albert Sep 11 2013, 08:14 AM Most of the following pictures have been taken by the Schneider company of Bad Toelz who did the dome. Kudos go to them for they did a magnificent job, as you will see here! The "new floor" seen from above. The worker is cutting some plywood as a mold for the concrete ring. The concrete ring is being cast. It also anchors the dome to the ground floor of the building.
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Post by Ron Walker on Sept 18, 2022 17:17:07 GMT -7
Posted by: albert Sep 11 2013, 08:21 AM Next comes a very sturdy wooden pattern or scaffold made from solid one inch plywood plates. This will serve as a pattern onto which to "lean" the brick wall....now the whole thing begins to look less like a black hole and more like a dome. Precise wood work on the center plate of the dome scaffold.
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Post by Ron Walker on Sept 18, 2022 17:17:25 GMT -7
Posted by: albert Sep 11 2013, 08:24 AM Lo and behold, here comes the brick wall! It grows quickly, it took two people less than a week to build. Holes were left in the outer wall to enable another scaffold to go up on the outside. Clearly these guys knew what they were doing!
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Post by Ron Walker on Sept 18, 2022 17:17:51 GMT -7
Posted by: albert Sep 11 2013, 08:29 AM
Look at the beautiful work here, the final stones have been put into their places and the wooden pattern has come out. The work on the outer walls is also beautiful, one of the men cut the bricks to size and the other one put them in place. They were fast as lightning, although they had never done this before.
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Post by Ron Walker on Sept 18, 2022 17:18:12 GMT -7
Posted by: Ron Walker Sep 11 2013, 09:58 AM WOW, Albert, super congratulations are in order. It's great to see that your projector will have a permanent home. What a unique way to construct a dome. Heck, even the wood support to build the brick dome could be reused to make another dome.
I can't wait to see your project as it progresses. Again congratulations!
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Post by Ron Walker on Sept 18, 2022 17:18:32 GMT -7
Posted by: albert Sep 11 2013, 10:36 AM The inner layer of the dome is the projection surface. To insure that this was precise to 1-2 mm, the plasterers came up with a metal stick with a ball joint at the bottom. This was attached to the exact center of the dome marked on the false floor. Using this stick as a gauge to smooth out the plaster while it was still wet, they got a seamless, almost perfect surface. It is much better than any other dome I have seen so far. No seams, segments or any other rough spots. Ideally when combined with a rim light made of LED strips, this will make the dome "disappear" even for light scenes. I cannot wait to see the final installation! The sound will be dampened by carpeting on the floor and on the walls. So far the dome is a real echo chamber but the odd reflective spots on the perimeter are way above the spectators heads when the planetarium will be in use. I think the final acoustics will be ok.
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Post by Ron Walker on Sept 18, 2022 17:18:52 GMT -7
Posted by: albert Sep 11 2013, 10:44 AM
On Monday we made a first lighting test. First we lit up the dome using a stage light and tried different gels to see if any rough spots would show.
I had decided to bring the ZEISS Starball without the eyelid mechanisms. A small 12 Volt power supply served as the power for the lamp. We set the starball on a blanket onto an improvised table made of styrofoam insulation materials and turned it on. We could not get the room totally dark, no doors are in yet. So we taped some black tissue over the door openings but it never got completely dark. Talk about hearing your heart beating in your throat! Light on! What a moment. The sky was impressive even under these primitive conditions. Of course we had bright spots where stray light came out of the starball, this is normally covered by the eyelids. But I found my way around!
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Post by Ron Walker on Sept 18, 2022 17:19:14 GMT -7
Posted by: albert Sep 11 2013, 10:50 AM QUOTE(Ron Walker @ Sep 11 2013, 06:58 PM) * WOW, Albert, super congratulations are in order. It's great to see that your projector will have a permanent home. What a unique way to construct a dome. Heck, even the wood support to build the brick dome could be reused to make another dome.
I can't wait to see your project as it progresses. Again congratulations!
Hi Ron,
you seem to be an early bird! Here its almost dark, but over where you are it must be real early in the morning!
Let me tell you how inspiring I found your story and I check in often to see where you are.
I am very happy to share these images with you and I still cannot believe it all happens right now.
I will go on with this until we do our first show. I would like to have you here for that!
All the best
Albert
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Post by Ron Walker on Sept 18, 2022 17:19:39 GMT -7
Posted by: albert Sep 11 2013, 11:02 AM
Here is a time exposure of what we saw. You can see the "open" star ball on top of the styrofoam tower. I darkened the image slightly to better bring out the stars. Like in the real world the time exposure brought out a lot more stars than we could see with the naked eye. This looks very promising indeed. I was concerned with the roughness of the surface but it is just perfect. I don't know what this image will look like downsized and compressed to hell as it is.! But one should be able to see Orion, the Bull and the Pleiades . I will do another improvised test with video projection thru a fisheye lens ASAP just to see the difference, if I can make it into the dome before the other work will resume. BTW we had about 100 mosquitos quietly sitting on the walls of the dome. They didnt budge even when we turned on the 500 W stage light....They seem to have liked the climate and decided to stay there for the winter. How do yo swat a mosquito on a dome 15 feet above?
Now we will have to wait for the other things to be finished. We still do not have the final floor, heating and air condition. But the end is in sight and I hope we can open around Christmas or early next year.On Friday I hope I will be able to test some LED strips for the cove lighting. I dont know yet if we will be able to get the LEDs sufficiently far away from the dome surface to have even lighting conditions.
Let me know what you think, especially about the open structure. I will keep you posted on our progress.
Albert
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Post by Ron Walker on Sept 18, 2022 17:19:58 GMT -7
Posted by: Ron Walker Sep 11 2013, 01:41 PM I really do love German engineering and precision. 1 to 2 mm's on a plaster dome is phenomenal. I'll be happy to be 1 to 2 inches if I'm lucky. I note that their float is also curved to match the radius of the dome, really well thought out and done. I don't think you will have any bad acoustical problems either. The worse one I found reflects everything back to the center where the projector will be and like you say, the other reflections will probably be too high to be a problem. Also having half the chamber open will help as well.
I would imagine the projector will be permanently installed under the dome but what about seating? Will it be rows around the dome or directional? I would imagine two rows around. Now a question as to permanently mounted seats or not. I could imagine small concerts given with the performers directly in front of the projector facing out towards the larger hall. The circular back wall acting as a kind of band shell adding a natural hall reverberation to the performance. The outer area could be used for a multitude of things from the standard displays one would expect, to a meeting room before a show, to even a wine and cheese, or complete dinner for that matter before a show. The possibilities are really endless.
Are you planing on any kind of audio for the planetarium? You probably won't need any amplification for the lecturer, but I'm wondering about any extra music and special effects. And, if so, where will they be controlled from? Have you thought at all about having dual controls? The original set at the machine and a second set off to the side where everything could be controlled.
I am really so happy for you. Your project is so well thought out and constructed. The time exposure makes me want to do the same here, even if only on a wooden framework. Just to see the stars for the first time must be exhilarating!
Looking forward to more, and again, congratulations.
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Post by Ron Walker on Sept 18, 2022 17:20:24 GMT -7
Posted by: Ron Walker Sep 11 2013, 01:45 PM Another observation. That outer dome sticking up through the floor looks like a great screen for a multitude of projections. Just a thought.
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Post by Ron Walker on Sept 18, 2022 17:20:45 GMT -7
Posted by: mrgare5050 Sep 12 2013, 09:06 AM
did someone say Zeiss??? gare van winkle, awakening.
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