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Gallileian Renaissance

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#76 Kasmos

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Posted 17 March 2019 - 03:47 PM

WOW, Nice Job! waytogo.gif

 

I was stunned when I first saw it. I had already thought it was an inspiring project, but now more so.

 

Now I have yet another 'thing to do' to put on the list. grin.gif  


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#77 Vesper818

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Posted 17 March 2019 - 03:52 PM

I'm trying to wait patiently for an update. ....

What's up with your project? "Enquiring minds want to know!" grin.gif

Cheers! Bob F. cool.gif



2w8qci.jpg


grin.gif grin.gif grin.gif


😨

Now I gotta go wash out my eyeballs,Bob!

😊
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#78 Kasmos

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Posted 17 March 2019 - 04:04 PM

I ran across this the other day and thought of this topic.

Charles Frank Galileo.jpg


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#79 Astroman007

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Posted 20 March 2019 - 12:54 AM


Now I gotta go wash out my eyeballs,Bob!

Same here! shocked.gif

 

I hate those rags.


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#80 droid

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Posted 21 March 2019 - 02:45 AM

From Galileo to newton, great minds think a like

 

http://dobstuff.blogspot.com/


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#81 Vesper818

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Posted 21 March 2019 - 12:49 PM

That's a cool post , Andy. I wonder if coating the right sized negative lens would work for a primary for a replica of Newton's reflector.
A flare-up delays progress on the Galileian eyepices, but I'm getting a lot of reading done.
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#82 1000mmFL

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Posted 14 October 2019 - 11:06 AM

I just noticed this thread.

 

I too got the bug to build a replica of Galileo’s telescope earlier this year. I recently finished it and a picture is posed on the ATM, Optics and DIY Forum/Post your home made scope thread.

 

I did a lot of research on the idea and wasn’t happy with any of the kits or DIY instructions on the internet as they weren’t very much like the real thing. However, I did come across the work of Jim & Rhoda Morris who built museum quality replicas of Galileo’s telescopes. Their main page is http://www.scitechan...lileotelescope/ and the referenced pages go into excruciating detail on their analysis and construction.

 

Like you, I wanted to build something that delivered the experience of the original but was a little easier to construct.

 

My telescope was constructed of 1.5” and 2” cardboard mailing tubes and wood disks. Multiple layers of tubing were used for the objective and eyepiece sections and a smaller tube (made from cut and reglued 1.5” mailing tube) was used to make the rear adjuster (the front isn’t adjustable). The main and adjusting tubes press fit into the objective and eyepiece sections to allow disassembly. The tube assembly was covered with leather (sold in 8.5x11 sheets at the craft store and glued on). I had rubber stamps made from copies of the decorations used on the original and applied them with gold ink to get an authentic look.

 

The lenses used are close matches to the originals that are commercially available. The objective is a 40mm plano-convex with a 1000mm focal length. The eyepiece was a 25mm plano-concave with a 50mm focal length. These lenses worked well but the field of view was poor (as some have mentioned). I switched out the concave eyepiece for a 25mm plano-convex with a 30mm focal length according to Kepler’s suggestion. This produces a much more usable instrument with 33x magnification and a wide field of view. In addition to being historically correct, the plano lenses should minimize spherical aberration and the long focal length should reduce chromatic aberration.

 

The images aren’t bad. I can see craters on the moon, the rings of Saturn, and the moons of Jupiter quite clearly. The Pleiades cluster is bigger than the field of view and shows some aberration on the outer edges of the image (probably coma) but you can see lots of stars. There is a slight bit of glow around the moon but its not bad and isn’t significant around stars and planets.

 

I probably spent a lot more time and money on this than I would have just buying low end telescope but it’s very usable and pretty cool!


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#83 Vesper818

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Posted 15 October 2019 - 09:34 PM

That is beautiful! Mine has still not had first light , as it has no mount yet. Your mount is clever. Very beautiful execution!
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#84 1000mmFL

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Posted 15 October 2019 - 10:37 PM

That is beautiful! Mine has still not had first light , as it has no mount yet. Your mount is clever. Very beautiful execution!

Thanks. It's not perfect but it came out the way I wanted it. What's more important is I can see all of the things Galileo saw and more.

 

The mount was just something simple. As you can see, the main mount is just a piece of wood with pipe clamps screwed into it (painted black for effect). The piece of wood actually has a 1/4-20 thread insert on the bottom so I can mount it to a standard camera base and I bought a 70" camera tripod for it. The camera base wasn't very stable (and a but jerky) so I put the wood extension on it with bolt axle and some nylon bearings. It's not perfect but usable. These long scopes need to sit up high to work properly. An elbow would be useful for high angles!

 

I'd be interested in seeing how yours works from an image standpoint. It looks like you used a biconvex lens which should produce more spherical aberration but I wonder how much of a difference that really makes. I can focus mine to see the rings of Saturn and the moons of Jupiter which take some pretty sharp focus at 33x. I do get some aberration at the edges of the image which I think is either coma or spherical (I'll have to look more closely).

 

I like that you made your adaptable to standard eyepieces which allows some experimentation (you have to pop the end off and replace the lens, possible with a size adaptor on mine). I have contemplated trying a 20mm, 25mm FL lens for 40x or even a 15mm, 20mm FL for 50x but the FOV with the current lens is very usable. Additionally, at 33x, the moon fills the FOV and the Pleiades won't fit so it's good enough for now. 


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