Bad Toelz Planetarium- inside the Zeiss ZKP 2 projector

Posted by: mrgare5050 Mar 29 2021, 11:20 AM
Fabulous pictures!

Posted by: albert Mar 29 2021, 10:42 PM
QUOTE(Ron Walker @ Mar 29 2021, 07:42 PM) *
It is interesting that the pots are only in the control circuits as they appear to be rather heavy duty like they are designed for control of heavy current or motors directly.

When I rewired and went to a more "brute force" type of control, all of my variable power sources are switched before the 120 volt AC Variacs where the current is at its minimum. This then drives various transformers to provide the lower voltages required to run the various motors and lamps. Full wave rectification is provided after the step down transformer for those circuits that require DC current. All in all it has worked very well for me.

The projector itself is quite silent. The only sound if you really concentrate is from two whisper box fans on each star ball. They are run in series and then powered by the star ball lamp circuit so they are sure to come on with the 500 watt lamps. Since each box fan at full power is actually at half voltage they are extremely quiet. The drive motors make no noise at all as they are all enclosed within the projector proper.

There is a tad of hum/vibration that I can hear at the control desk from the Selsun readout motors but is not heard in the visitor area. I am somewhat of a nitpicker here but it has never been enough for me to do anything about it probably because it comes and goes as the load on the readout gears changes with load. It is easy to just let the system move a bit more and things go silent.

Hi Ron!

The control pots are overbuilt to last longer- I have found some in the "spares" box where the threads had come off the windings- so if you think it is made to last 30 years or so, in a big & busy planetarium with several shows per day....

If I had to redo the console from scratch I would go your way, too. I believe there might be more of a time bomb type problem in the consoles than in the machines.

Posted by: albert Mar 29 2021, 11:12 PM
Ron your control console looks like a spaceship or a cockpit - great! I think I remember about the SelSyn readout dials. That is sadly missing in my own planetarium- Iwould like to have a direct readout of the projector position without having to turn on the meridian or the ecliptic/equator.

Perhaps you could show us what your ecliptic and other help lines look like. I Imagine that the lining up in a dome of a different diameter is very hard to do.



My own help lines are as you can see rather simple - just lines, no grids or days or months.

Posted by: Ron Walker Mar 30 2021, 12:08 PM
QUOTE(albert @ Mar 29 2021, 11:01 PM) *
Yeah! thank you so much for these pictures. I also believe in blue light in a planetarium. The Zeiss projector is a special shade of blue itself- it changes color with different lights- - my seats- per chance- have blue covers- and with the new LED systems blue really is not a problem anymore. On the base ring of the projector the lights are 12 volt car lamps- and half of them with a very dense blue glass filter in front of them. In the "spares" box there were several cracked filters, the heat is tremendous, while the white filters remain cold- in the old days a blue light was in essence an oven with a bit of light coming out....you could heat a pizza or a cup of coffee on these filters.

I'd be a bit careful with UV LEDs though- they might not be good for the eyes.

I must admit that when I am between shows on Saturdays, I have occasionally taken a nap in the planetarium. There I have experimented with different colors- I seem to sleep best under an orange evening glow type sky....smile.gif

Red light does not look bad, too...



I was very lucky to have a LED lighting company right across the street when the planetarium was built. They were happy and interested to experiment with the cove lights. One of their major jobs in the last few years was to equip the Sistine Chapel in Rome (Michelangelos ceiling frescoes) with LED lighting. And so they had interesting LED modules with different properties, and were interested to use the planetarium as a "showroom" across the street. We even had a lighting congress with light designers in the theater and could show the planetarium as an example. The main problem was to get the LED modules to dim down correctly. The last 10 to 20 % were the real challenge, also a new one for the company.

The planetarium technician is also experimenting with LED lights for the projector. These small lamps cost a fortune and get very hard to find. On the older ZKP 1 I had tried LEDs for the planets, but found them too blue, even the warm white ones, as long as the star lamp was still a normal type lamp, always a little on the yellow side.

Like you I am a nitpicker in these things!

These particular UV light are the "party" variety and technically not in the spectrum that does damage (or so they say). I have been really studying the "C" part of the UV spectrum for use in killing off viruses and such. These wavelengths are rather nasty and you should not expose anyone to the direct rays.

I can see sunset color light as inducing heavy eyelids as the body expects night to come right after.

When I was converting over to LED lights I had plans to use the for min room illumination as well as sunrise/sunset glows but ran into the same problem with obvious steps in the light level where you want the smoothers possible. There were some controllers that did a nice smooth fade but they were quite expensive so I went back to incandescent bulbs and I agree they have a warmth that LED's just can't touch.

Posted by: Ron Walker Mar 30 2021, 01:18 PM
Here is part of the sky around Orion with brilliant Sirius to the Left and the Hyades with bright red Aldebaran at top center. I believe your projector does at least 3K more stars so is a fuller sky. Sirius doesn't bloom as in this time exposure but it does "pop" as I am using a three watt Led in its projector.



One of 27 constellation outline projectors that move with the main projector.



And once again the indicator lines in this part of the sky.

Posted by: Ron Walker Mar 31 2021, 10:38 AM
These pictures are wonderful, and just what I had in mind. The detail on the auxiliary lines is fantastic. Like the old Zeiss machines. And a lot of separate projectors for these lines alone.

It is surprising how much of an exact copy at exactly half scale my projector is. Certainly the "designers" of it had a Zeiss III, or IV to take measurements from.

I don' think that your sky is less detailed - of course the separate projectors for bright stars like Sirius are another detail missing in my machine. But given the small size one cannot ask for too much. The flashlight on the exposures comes off perfectly dosed...must be great to be able to just go over to the dome...I have to drive 130 kilometers to get to the planetarium since I am not living next door to it.

I never realized you were so far from your planetarium. I cannot imagine having to go that far to tinker. I am actually very happy with the detail of my sky in that I need to look out of the corner of my eye to see the very faint sixth magnitude ones.
I have also never been anywhere where the real sky looked as good or better.

I cannot begin to imagine how much work it has been to get this to project so perfectly well. I guess your dome is a lot smaller than the one the Minolta had been made for originally?

This is a very interesting projector in that it was originally designed for use in a 40 to 50 foot dome. The people I bought it from had a thirty foot dome but wanted the extra goodies that came with the bigger machine. So they had custom star plates made for a thirty foot diameter dome. However there were some other things that I believe were just adjusted for (and some of the adjustments appeared to be ignored) such as the extra parallax adjustment for the planet projectors as they would need to angle in slightly more because the dome screen was somewhat closer. The same goes for the projection of the help lines. As you have noted, I did manage to get them fairly close but it was one of those things where I wanted the projections to be close to dead on everywhere around rather then perfect at one place and really off ninety degrees away.

And the planet positions seem to be perfect as well. That in itself is a feat, I guess you had to start this setup from scratch.

Other then the parallax problem, the setting of the planet projectors was fairly easy. When I first started setting the projector back for "The Christmas Star" show it would take a full day of adjustments and bloodied knuckles to get things "close enough". Then like the light bulb going on over my head I thought why not set the projector for the exact day with the most impressive conjunction which is the conjunction between Jupiter and Venus in two BC. Now the set up only takes about an hour. I write down the positions of the planets for the present epoch so it is east to get things back when I'm finished with that program for another year.

The ZKP 2 comes with a manual that describes the setup for a date in 1975....here one can see how old these machines are...have you used a program like stellarium to get the dates for setting up? I guess the process is similar- get the stationary points and the declination right and then set the planet on the date where it has to be...

There are marks on the main planet gears for setting in either 1971 or 1975, I don't remember, but I did go to Stellarium and set the projector exactly the day of my first show which was Friday the 13th of June, 2014. I had thought that I would have needed to adjust something in the last seven years of giving shows but no, not even the Moon. I read someplace that the projector was so accurate that no projection on the dome would be off more then one degree after five thousand planetarium years. On my dome that is about four inches. After seven years now I'm beginning to believe that just isn't advertising hype as even the Moon is holding its position. I find it kind of fun that I go into the dome and look forward in time to see what will be happening in the real sky in the future.

The constellation figures...another feature reserved for the bigger machines. On the hybrid planetariums they have the video projectors for all these effects. But the price is a grey sky, not a black one anymore. I had a friend come to visit the planetarium, and he said.."oh, YOU have a planetarium, not a cinema"!. For me the sky has to be black. And not polluted to begin with.

I always liked the constellation outlines when I do the constellation stories but the projector only came with three outline projectors. I wanted more and I wanted them to move with the projector itself. I built a bunch for about $5 each and now have 27 outlines that stay in perfect alignment on the dome. I am now going to make projectors for some of the more well known deep sky objects so a telescope view can be projected right where the object is in the sky. I find it interesting that visitors can easily see the difference between a true planetarium and a cinema. So many of the younger set have never seen a true planetarium sky and can still experience it in the places where a true planetarium is preserved. As pollution continues to destroy more and more of a truly dark night sky, a planetarium will be the only place left where they can see one.

Very close to the sector you project here I saw a strange object last night when I wnet out to look at the real sky. It was extremely bright and moved too fast to be a plane.. no noise. It was not a satellite either because the light went out abruptly after I had seen it move between Aldebaran and one of the orion stars.

I remember watching what I thought was a vapor trail in late evening a few years back, and seeing it make a ninety degree turn and continue on.

Do you have the auxiliaries? I have a solar system and a meteor shower projector. No "UFO" projector though!

I have all three. I will get back out there and get some more pictures for you.

I only hope we can get people to see this with us again soon.

I believe we will be stuck with this virus or a variation of it for a very long time to come. We will need to adapt and live with it as we do with cold's and flu's. We will need to disinfect the air in our star chambers as the show must go on.

Posted by: Ron Walker Apr 1 2021, 10:27 AM
"The ZKP 2 comes with a manual that describes the setup for a date in 1975....here one can see how old these machines are...have you used a program like stellarium to get the dates for setting up? I guess the process is similar- get the stationary points and the declination right and then set the planet on the date where it has to be...

There are marks on the main planet gears for setting in either 1971 or 1975, I don't remember, but I did go to Stellarium and set the projector exactly the day of my first show which was Friday the 13th of June, 2014. I had thought that I would have needed to adjust something in the last seven years of giving shows but no, not even the Moon. I read someplace that the projector was so accurate that no projection on the dome would be off more then one degree after five thousand planetarium years. On my dome that is about four inches. After seven years now I'm beginning to believe that just isn't advertising hype as even the Moon is holding its position. I find it kind of fun that I go into the dome and look forward in time to see what will be happening in the real sky in the future."

I went out and checked and the projector was originally set for 1-1-1976 (probably at the factory) which was just before the machine was installed and put in service for its first show on April 3rd, 1977.