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Post by Ron Walker on Apr 18, 2022 20:01:44 GMT -7
Posted by: Ron Walker Apr 2 2021, 01:36 PM "Now Ron that is REALLY a cool idea. I would be honored to make the Bad Toelz planetarium your twin planetarium."
We are both of a special breed that could see the value in giving some very useful projectors a new lease on life and allow them to do what they do best, help teach astronomy.
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Post by Ron Walker on Apr 18, 2022 20:02:13 GMT -7
Posted by: Ron Walker Apr 2 2021, 02:19 PM QUOTE(Scott T @ Apr 2 2021, 03:49 AM) * These pictures are like gold for those of us who do not have access to such machines - I had no idea that some stars/ objects had additional individual condenser lenses directly attached to the star plates + I just assumed 'fuzzy' objects had a separate projector.
Ron - what is the actual diameter of the star plates + would it be possible to post a photo or two of the condenser lens/lenses in isolation (the one covering the entire plate rather than the mini ones for 1st magnitude stars). I am a bit behind in my write up on the optical projector design thread but I am trying to work through the various options for the condenser lenses.
+ Do you happen to know the focal length of the main condenser lenses?
The star plates are approximately two inches in diameter.
The condenser set is a double plano/convex set with the flat sides pointing out, one towards the light source and one towards the star plate.
This double set also approximately two inches in diameter are screwed onto the back of the projector. I'm not exactly sure of the f.l. of these lenses but the sets optical center is about 4 1/2 inches from the filament of the lamp. I'm sure these measurements would come out to a more rounded number if measured in mm and not inches. My guess is that the star plates are actually 50 mm in diameter.
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Post by Ron Walker on Apr 18, 2022 20:02:32 GMT -7
Posted by: Ron Walker Apr 2 2021, 02:22 PM "These pictures are like gold for those of us who do not have access to such machines - I had no idea that some stars/ objects had additional individual condenser lenses directly attached to the star plates + I just assumed 'fuzzy' objects had a separate projector."
From what I can tell, Minolta was the only builder that put the condensers directly on the star plates. All I can tell you is that it works very well.
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