58 replies to this topic

[rob1986]

Thanks. You're a mechanically literate voice of reason. Decades ago I replaced the aluminum tube of a 4-inch f/12 refractor with decorative polished brass tubing of greater wall thickness. The resulting OTA was far more massive but actually proved to be just as stable because the mass was more uniformly distributed rather than concentrated at the ends.

Whats the length of that ota?

Granted of the accesory scopes, but a large refractor also puts all the weight at the ends.

And as my conclusion is that a wide dovetail will enable the SVP to carry an 8" F6 with usable stability, i think Im more than justified.

Especially if i replace the saddle instead of using an adapter. (Which will keep the weight closer to the axis)

Edited by rob1986, 26 August 2024 - 01:20 AM.

[CHASLX200]

Perhaps I'm just a pathological liar. But I have no doubt that there are many thousands of very satisfied owners of 102mm f/9.8 refractors carried by Great Polaris mounts and that very few find the combination "maxed out" unless they're taking long-exposure photographs in a gusty wind.

Just goes to show how this will vary by person. One may like a view in a scope while a others may think it shows too much color. Same for Coma in Newts as some are fine without a Paracorr while i can't live without a Paracorr.  Goes for mounts as well mel.  Once you jack up the power like i do you notice jitters while trying to focus.  I find it maxed out when i had a 120mm and 127mm fracts on my GP with the wood tripod . Once i slapped it on a Meade LX200 tripod it was much more steady freddie. So maybe i am on the one telling a lie..

 

This makes the mount a good 30% better.

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[rob1986]

Tripods need to be scaled to the payload. For 5kg a 1.5 of 1.75 is fine, for 10 to 15 kg i think you really need a 2" leg.

I wonder if meade had it right and that 1.5" shafts like the lxd 750 or the somewhat more compact atlas really needed 3".

Maybe the ASGT C10N would have fared better with a wide saddle and an alternate 3" tripod.

Or even 2.5"

[starman876]

WOW this thread turned into something else.   By the way, beautiful set up.  I am sure you enjoy it like a lot of people would.   I guess as long as you use the scope within the limits of what is normal everything is fine.  

[schiefspiegler]

WOW this thread turned into something else.   By the way, beautiful set up.  I am sure you enjoy it like a lot of people would.   I guess as long as you use the scope within the limits of what is normal everything is fine.  

Yes indeed. Arghh! As far as "the limits of what is normal," in my dotage I've reverted to being a visual observer, although when showing guests the Moon I often display a video image using the piggybacked 70mm f/10 refractor to point out features of interest before they look through the 6" refractor. A picture is worth a thousand words as they say. For this purpose the instrument has been a satisfying performer.

[rob1986]

When things look perfect there isnt much on topic to say...

On the otherhand this post demonstrates that i my own beautiful white OTA with SVP and wooden tripod plans will also succeed, and juat maybe some paralax rotating rings might actually be on the table after all, which makes this post even better sounding.

Edited by rob1986, 26 August 2024 - 08:57 AM.

[schiefspiegler]

2017 eclipse - Meade 127ED and ETX90.

 

-drl

That's a lovely setup. The Meade 5" f/9 ED apo (objective lens designed for Meade by Richard Buchroeder of the University of Arizona) can be a stunning performer. And I'm confident that the LXD-75 mount did the trick.

Edited by schiefspiegler, 26 August 2024 - 12:11 PM.

[schiefspiegler]

Please forgive me if the following is considered "blasphemy". Has anyone ever replaced the achro lens of a vintage Unitron with a modern Apo lens and have the best of both worlds? Just thinking. Plus, you would save the money on a new Moonraker. Unless you really love chrome.

 

Clear skies and keep looking up!

RalphMeisterTigerMan

That would certainly be a noble endeavor, but obtaining a "drop in" f/16 apo objective lens might be prolematic. I wish that a sub-aperture corrector like the Chromacorr were available! That might be the ideal way to upgrade the performance of a classic Unitron doublet.

Edited by schiefspiegler, 26 August 2024 - 12:14 PM.

[starman876]

That would certainly be a noble endeavor, but obtaining a "drop in" f/16 apo objective lens might be prolematic. I wish that a sub-aperture corrector like the Chromacorr were available! That might be the ideal way to upgrade theperformance of a classic Unitron doublet.

very hard to find a 4" F15 ED lens

[rob1986]

That would certainly be a noble endeavor, but obtaining a "drop in" f/16 apo objective lens might be prolematic. I wish that a sub-aperture corrector like the Chromacorr were available! That might be the ideal way to upgrade theperformance of a classic Unitron doublet.

You couldnt ask stellarview or one of the small premium guys to make a custom ED doublet? I at f15 i doubt a triplet would get you much...

[schiefspiegler]

You couldnt ask stellarview or one of the small premium guys to make a custom ED doublet? I at f15 i doubt a triplet would get you much...

Agreed. At these modest apertures and long focal ratios an ED doublet should have superb color correction -- probably no discernible color error visually. 

[rob1986]

Agreed. At these modest apertures and long focal ratios an ED doublet should have superb color correction -- probably no discernible color error visually.

I'd bet photographically too.

[starman876]

https://www.altairas...cuser-467-p.asp

 

found an F11 scope for a reasonable price.   No F15's

 

https://www.altairas...ope-13522-p.asp

 

the above maybe in stock

Edited by starman876, 26 August 2024 - 11:39 AM.

[Retentive]

The sheer beauty of Unitron refractors -- their hallmark black and white paint scheme, the elegant "Uniclamps" for adding piggyback scopes and sliding tube counterweights, the polished metal knobs -- made the 5- and 6-inch Unitron refractors the stuff of boyhood dreams for geezers like me. Alas, as my late father lamented, "Son, why couldn't we have been born rich instead of good looking?" Compensating for inflation, the 6-inch Unitron fetched almost $70,000 in 2024 dollars.

In the words of the Irish Tourism Development Authority "There's a great future in nostalgia." I've attempted to recreate the aesthetic appeal of those classic instruments in a modest, far more affordable way. Adorning the living room of my Florida house is a much-modified Bresser 6" f/8 achromat with piggybacked 80mm f/8 and 70mm f/10 achromats. Granted, it's not a towering f/16 behemoth like the original that inspired it, but it never fails to draw a crowd at star parties.

In my era that was and is the ultimate set up, now I have to get out my 1960s Norton Star Atlas and dream!

[deSitter]

That's a lovely setup. The Meade 5" f/9 ED apo (objective lens designed for Meade by Richard Buchroeder of the University of Arizona) can be a stunning performer. And I'm confident that the LXD-75 mount did the trick.

I got a great one, early production. Saw albedo features on Ganymede!

-drl

[CHASLX200]

I got a great one, early production. Saw albedo features on Ganymede!

-drl

My Meade 5" ED was good. Mount was not so hot on GO-TO's I had the older LXD600. Mount would be perfect if there was a way to mount other scopes on it and just use SLO- MO's.

[starman876]

OK back to Unitron stuff.   It is amazing after all these years people are still talking about them and trying to get setups to look like them. A real compliment about Unitron or the company that made them Nihon Seiko. even though Nihon Seiko went out of business (the demise of Unitron telescopes)  Unitron still tried to have other  companies make scopes for them. They just could not find anybody to make them with the same quality that Nihon Seiko used to make them. So Unitron telescopes came to an end.   

[badback]

   

Don't see how that mount can hold all of that.

        

Yeah, it looks like me at an all-you-can-eat buffet!

 

Rick

  BUFFET:

                    Big...

                       Ugly...

                          Fat...

                           "Feckers"...

                               Eating...

                                 Together.....    

[Garyth64]

Here's my version:

 

 

 

 

 

[Terra Nova]

Dear Schief, what a wonderful homage to the big U! You have hit it on the head and knocked it outta the park Sir! 
 

Gary, love yours too!

Edited by Terra Nova, 02 September 2024 - 10:05 AM.

[CHASLX200]

Gotta have the real deal for me.

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[starman876]

Here's my version:

 

ATCO RAO photo c.jpg

Beautiful scope

[oldmanastro]

The sheer beauty of Unitron refractors -- their hallmark black and white paint scheme, the elegant "Uniclamps" for adding piggyback scopes and sliding tube counterweights, the polished metal knobs -- made the 5- and 6-inch Unitron refractors the stuff of boyhood dreams for geezers like me. Alas, as my late father lamented, "Son, why couldn't we have been born rich instead of good looking?" Compensating for inflation, the 6-inch Unitron fetched almost $70,000 in 2024 dollars.

 

In the words of the Irish Tourism Development Authority "There's a great future in nostalgia." I've attempted to recreate the aesthetic appeal of those classic instruments in a modest, far more affordable way.  Adorning the living room of my Florida house is a much-modified Bresser 6" f/8 achromat with piggybacked 80mm f/8 and 70mm f/10 achromats. Granted, it's not a towering f/16 behemoth like the original that inspired it, but it never fails to draw a crowd at star parties.

What a wonderful 6" Unitron homage setup. Reminds me of the time I spent looking at the Unitron brochures and just dreaming during my youth. The Skyview Pro mount is quite capable of handling all that gear. I had the same mount with the tripod extension, I think it was 16". The telescope was a Celestron C6-R f/8 achromat. With the extension the mount transforms into a pedestal and a very steady one. It allowed my C6-R to be used for observations near the zenith. Never had any issues with vibrations. 

[Exnihilo]

A lot of scope for the mount, but beautiful!

[schiefspiegler]

Dear Schief, what a wonderful homage to the big U! You have hit it on the head and knocked it outta the park Sir! 
 

Gary, love yours too!

High praise from an "old hand" like you! To many members of our generation the proper color scheme for telescopes is black and white.

 

The old Tasco 20TE was also downright arousing back in the day...   https://www.cloudyni...sky-tasco-20te/

Edited by schiefspiegler, 03 September 2024 - 06:42 PM.